This study introduces a groundbreaking technique aimed at enhancing the efficiency of polarization-resolved second-harmonic generation (P-SHG) imaging for larger samples. Traditional P-SHG imaging methods are characterized by lengthy processing times and the need for costly equipment, posing significant limitations for their application on a larger scale. By merging the initial low-resolution P-SHG imaging with advanced image upscaling via Enhanced Super-Resolution Generative Adversarial Networks (ESRGAN), our approach significantly reduces the imaging time by over 95%. Crucially, this method preserves the quality and accuracy of the imaging outcomes, reduces laser-induced sample damage, lowers the cost of optical components, and expands the accessibility of P-SHG imaging for comprehensive studies of large biological and material samples. Our innovation paves the way for new scientific discoveries and technological advancements in whole-sample imaging.

This paper presents an image analysis method that helps with image tomography; several texture techniques can provide a better analysis for physicians. Nowadays, Tomographies have been an excellent tool for obtaining much brain information. Color tomographies are also an excellent tool for detecting some illnesses.

Metabolic analyzers assess human health by measuring oxygen (O2) consumption and carbon dioxide (CO2) production from expired breath. The goal of this work was to explore simultaneous detection of O2 and CO2 gases using a compact optical sensing configuration based on stacked fluorescent thin films. We report the design, fabrication, and characterization of a prototype O2 and CO2 optical sensor capable of measuring metabolically-relevant gas concentrations with the potential to be miniaturized for operation in face-worn metabolic analyzers.

A polymeric grating prepared by femtosecond laser microfabrication is demonstrated in this study. This diffraction grating is fabricated in an epoxy-based negative photoresist on glass substrate by femtosecond laser induced two-photon polymerization and bonded with a polydimethylsiloxane (PDMS) microchannel. The transmission spectrum of such an opto-microfluidic structure can be tuned by changing the refractive index of the liquid flowing in the microchannel. The applications of such an opto-microfluidic structure in sensing, including refractive index sensing, are explored in this study.

We demonstrate the combined use of lock-in phase and amplitude for enhanced chemical-specific image segmentation in Coherent Raman Microscopy. Using 2D amplitude versus phase plots of Amplitude-Modulated Stimulated Raman Scattering (AM-SRS) microscopy detected using lock-in amplification, we achieve improved separation of Raman resonant versus non-Raman background signals. The lock-in phase identifies non-Raman processes associated with a finite lifetime. We demonstrate the utility of this approach for improved mineral (chemical)-specific imaging in economic Lithium-bearing ores.

Antimicrobial photodynamic therapy (aPDT) is increasingly being explored for treatment of periodontitis. Here, we investigated the effect of aPDT on human dental plaque bacteria in suspensions and biofilms in vitro using methylene blue (MB)-loaded poly(lactic-co-glycolic) (PLGA) nanoparticles (MB-NP) and red light at 660 nm. The effect of MB-NP-based aPDT was also evaluated in a clinical pilot study with adult human subjects with chronic periodontitis. Dental plaque samples from human subjects were exposed to aPDT-in planktonic and biofilm phases-with MB or MB-NP (25 µg/mL) at 20 J/cm² in vitro. Patients were treated either with ultrasonic scaling and scaling and root planing (US + SRP) or ultrasonic scaling + SRP + aPDT with MB-NP (25 µg/mL and 20 J/cm²) in a split-mouth design. In biofilms, MB-NP eliminated approximately 25% more bacteria than free MB. The clinical study demonstrated the safety of aPDT. Both groups showed similar improvements of clinical parameters one month following treatments. However, at three months ultrasonic SRP + aPDT showed a greater effect (28.82%) on gingival bleeding index (GBI) compared to ultrasonic SRP. The utilization of PLGA nanoparticles encapsulated with MB [1,2] may be a promising adjunct in antimicrobial periodontal treatment.

Water salinity is a key factor in bodies of water, affecting a variety of physical and biological processes. However, traditional methods of measuring salinity have disadvantages such as complex instrumentation, time-consuming procedures, and frequent calibration requirements. D-shaped fibers offer a new approach and offer advantages such as real-time monitoring, non-invasiveness and resistance to electromagnetic interference. The unique design of the D-shaped fibers allows them to create an evanescent field on their flat side, allowing them to interact with their environment. As the salinity of the water changes, the refractive index of the medium changes, affecting the transmission of light through the fiber. Thus, monitoring these light changes allows for accurate measurement of water salinity in real-time. This article examines the use of D-shaped optical fibers as a promising and effective method for measuring water salinity by simulating the transmission of light through D-shaped fiber to find the response to the change in water salinity.

This paper introduces a novel co-packaging method for on-chip hybrid laser integration with photonic circuits, employing photonic wire bonding. The process includes die-bonding a low-cost semiconductor DFB laser into a deep trench on an SOI chip and coupling it to the silicon circuitry via PWB. After characterizing the laser's LIV and optical spectrum, a tunable wavelength-current relationship is established using a swept-frequency laser (SFL) method. Successful characterization of the resonators in PIC is demonstrated with SFL, showcasing signal detection comparable to off-chip benchtop laser measurements.

This work presents the optical simulation of an integrating sphere using Trace-Pro. Our results show that it is possible to obtain an efficient spectrophotometer with similar commercial performance.

This work presents the study of a new oil and gas oxygen analyzer using a technique based on optics. This analyzer using spectrometry helps improve the analysis process and the health of the people in the process plant and the environment. Data was acquired from the primary plant AA in the refinery in Salamanca, Guanajuato. Tunable laser diode absorption spectroscopy is the method used.

White lighting-emitting diodes (LEDs) become energy-efficient light sources in households and commercial buildings, on streets and highways, and at stadiums and construction sites. In general, lenses and mirrors are used to control the spatial distribution of white LED light. In this work, we proposed to use optical diffuser, the key optical device in scattering optics, to achieve the desired figures of merit for white LED lighting.

Exposure to blue light emitted by white LEDs poses health risks, including potential damage to eye tissues, increased risk of breast cancer, and disruption of the circadian rhythm. Reduction of the blue light component and optimization in light distribution are important to achieve high illumination quality for a white LED. To optimize the light distribution of LEDs, we designed a lens prototype which can effectively eliminate glare and transmit light. The polymer film with yellow phosphors doped into a low-cost, transparent, and flexible PDMS matrix is one of our solutions to absorb blue light. The polymer film can be attached to a commercial LED lamp. However, one needs to determine the optimal balance between film thickness and phosphor concentration to achieve better blue light control and light transmission. Leveraging the blue light absorption capability and tunable emission peak of CdSe/ZnO quantum dots (QDs), our study explores the potential application of a CdSe/ZnO quantum dots-filled PDMS film to absorb blue light while emit warmer light. The QDs-PDMS polymer film exhibits a greater capacity to attenuate blue light while maintaining higher transmission levels compared to the phosphor-PDMS polymer film. Due to the strong blue light absorption of QD, a considerably lower QD concentration is required compared to phosphor to achieve the desired level of blue light absorption.

The technological scope of nanoparticles has expanded in recent years due to the wide applications they can have. Therefore, this study focused on synthesizing and analyzing the optical and structural properties of pure and gold-doped zinc oxide nanoparticles. Zinc oxide nanoparticles were synthesized using sol-gel process and spin coating method. The effects of pH concentration (8-10) of ZnO pure solution were studied as a function of 1% of gold doping. The optical, structure and morphological properties of zinc oxide pure and Au-doped were studied using Spectroscopy Ultraviolet Visible, X-ray diffraction, Raman Spectroscopy, and Scanning Electron Microscopy.

We demonstrate a Bismuth (Bi)-doped fiber laser (BDFL) that generates pulses through passive Q-switching. Stable Q-switching operation was attained, with the shortest pulse width of 0.5 µs, and a tunable repetition rate ranging from 51 to 89 kHz. These results provide evidence that a simple configuration employing a commercially available semiconductor saturable absorber (SESAM) is suitable for the pulsed operation of BDFL in the 1700 nm region and offers potential for further development.

We report on the absorption coefficients of several popular Neodymium-doped laser crystals at wavelengths longer than 870 nm. In this study, high-resolution absorption spectra of Nd:YVO4, Nd:GdVO4, Nd:YAG, Nd:YLF, and the composite Nd:YVO4/Nd:GdVO4 crystals were measured in the 870-920 nm range to identify suitable wavelengths for excitation. Such wavelengths correspond to the lowest quantum defects in these crystals. According to the obtained absorption spectra, the most appropriate pumping wavelengths of the individual Nd:YVO4 and Nd:GdVO4 crystals are 914 and 912 nm, respectively. At the same time the composite Nd:YVO4/Nd:GdVO4 crystal provides a broad absorption spectrum approximately between 910 and 916 nm. Moreover, the absorption spectra of Nd:YAG and Nd:YLF crystals reveal that laser diodes at 946 nm and 908 nm can be the best choice to excite these two widely used gain media.

Abstract: We will present the application of femtosecond laser-induced breakdown spectroscopy (fs-LIBS) covering both ultraviolet (UV) and visible regions in the analysis of various metallic targets. We examine the signal strength and spatial resolution possible with a high acquisition speed fiber coupled spectrometer combined with a kHz femtosecond laser, in scanning mode. Previously [1] we have demonstrated that fs laser induced Laser-Induced Breakdown Spectroscopy (fs-LIBS) can provide information about the conditions in a plasma produced during ablation of a metal target by 35fs laser pulses. We also showed that these conditions could be correlated with the nano scale surface modifications that resulted. Here we concentrate on the quality of spectra which can be recorded for single and few pulse ablation, by scanning the laser across a surface, using a computer controlled XYZ stage. Femtosecond lasers are high intensity, but low energy compared to the more typically used nanosecond systems (mJ compared to J) and so can produce less surface damage during surface ablation, as well as desirable nano-scale surface modifications [2],[3]. We will present results in which we vary the number of laser pulses used to irradiate single spots and overlapping spots during scanning. We will also assess the spatial resolution of element identification which is available as a function of scanning and acquisition speed, for different targets. We seek to provide fast detailed mapping of sample surfaces in 2D and the findings from this study will advance the capabilities fs LIBS as a promising tool for rapid and precise elemental analysis, appropriate for studying delicate or valuable samples and causing minimal surface damage. References 1. Hayat, A., S. Bashir, D. Strickland, M. S. Rafique, B. Wales, S. Al-Tuairqi and J. Sanderson, “The role of laser fluence and ambient environments on femtosecond laser induced breakdown spectroscopy and on surface morphology of Mg and Zr,” J. Appl. Phys., Vol.125, No. 8- 083302-133695, 2019. 2. Labutin, T. A., V. N. Lednev, A. A. Ilyin, A. M. Popov, “Femtosecond laser-induced breakdown spectroscopy” J. Anal. At. Spectrom., Vol.31, No. 1- 90-118, 2016. 3. Lin. Z. and M. Hong. “Femtosecond Laser Precision Engineering: From Micron, Submicron, to nanoscale.” Ultrafast Science. 2021;2021.

This experimental study explores the spontaneous generation of multimode solitary waves in hollow-core fibers, examining their relation to organized instability. By systematically varying pressure and monitoring mode/spectral stability, a transition stage reveals spatiotemporal complexity. The study poses a fundamental question: whether solitary waves precede and drive complexity, or if self-organized instability guides the system toward a stable attractor. The research contributes insights into the dynamics of nonlinear optics and highlights the critical interplay between solitary waves and system stability.

Ultraviolet-B (280-315 nm) AlGaN-based laser diodes are simulated versus the AlN molar fraction for the electron blocking layer on the p-side. Polarization charge effect is included. Basic laser diode characteristics are presented and analyzed. The modeling results indicate that there is an optimum AlN molar fraction where the laser performance can be achieved with improved slope efficiency and reduced threshold current.

We report on efficient Diode-pumped Nd: YVO4 and Nd: GdVO4 Continuous Wave (CW) lasers pumped at 914 nm and 912 nm, respectively. Both lasers produced continuous-wave radiation with >10 W of average output power

We report on efficient diode-pumped Nd:YVO4 and Nd:GdVO4 continuous-wave (CW) lasers pumped at 914 nm and 912 nm, respectively. Both lasers produced polarized radiation with >10 W of average output power.

This work presents an approach to Epilepsy and some engineering techniques, in this case, photo modulation. Laser therapy has been improved since the early 60s. Here, we will present a characterization based on the current laser techniques. In this case, the power, distance, and kind of laser are used.

We discuss how to derive the surface photoconductivity from the measured change in the reflection and transmission amplitudes in pump-probe spectroscopy. We show how to account for optical nonlinearities, which distort the photoconductivity depth profile at high pump fluences. We provide exact analytical expressions for the reflection and transmission amplitudes, considering optical nonlinearities such as saturation and two-photon absorption

Introducing a wideband tunable mode-locked fiber laser operating in the spectral range from 1856 to 2000 nm, with a 3.5 MHz repetition rate and over 5 mW average power from the seed fiber laser. It utilizes 2 m Thulium-Holmium co-doped fiber (THF) as the gain medium, incorporating a semiconductor saturable absorber mirror (SESAM) for passive mode-locking. This laser system achieves exceptional wavelength tunability while maintaining a low repetition rate. The self-starting nature ensures stable operation, with an average pulsewidth of 1.5 ns. The low repetition rate makes it suitable for time-resolved measurements and nonlinear frequency conversion. The laser's wide wavelength tunability, narrow linewidth, and low repetition rate make it valuable for scientific and industrial applications, including spectroscopy, gas sensing, and ultrafast photonics.

This study investigates the development of a Sagnac ring resonator with standard twisted and tapered fibers as a vibration detection device. The pump source for the characterization of the system is a pulsed figure eight laser in passive mode lock at a wavelength of 1544.6 nm and repetition frequency of 959 kHz. The proposed device has automatic retarder plates capable of intelligent positioning through neural networks, which enables us to adjust the temporal duration of the pulses, as well as the spectral width, realizing a stable output over time with controlled, stable, and precise pulses. The simulation of our interferometric device was developed in MATLAB; the experimental results were in good agreement with theoretical ones and highly reproducible. The proposed device had dimensions on the order of centimeters, a free spectral range of 4 nm and spatial frequencies of 0 to 10 1/nm. Therefore, the device’s implementation as a vibration sensor is considered practical. Having possible applications as the detection of mechanical imbalance fault in motors.

We propose and experimentally demonstrate a novel approach for the suppression of higher-order-mode oscillation in a few-transverse mode laser oscillator by decreasing the cavity length. This approach works without any cladding mode filtering. When used in forward pumping configuration, it allowed us to create a master oscillator – power amplifier system with 7 W of output power limited by the onset of Yb self-pulsing, without additional components.

We demonstrate a method to simultaneously generate and focus, to the nanoscale, XUV high harmonics, with high numerical aperture, thus overcoming the lack of high quality and affordable external focusing elements for XUV light. By illuminating MgO nanostructured crystal surfaces with an 800nm, femtosecond laser, we achieve simultaneous generation and focusing of a coherent XUV beam with high numerical apertures of up to 0.35. Future exploration involves shorter wavelength harmonics and higher numerical aperture structures to shrink the focal spot below 100 nm, enabling applications like direct nanoscale laser writing, and nanoscale imaging with XUV photons and with photoelectrons.

We present a novel method for the suppression of laser intensity noise and pulse-to-pulse energy fluctuation, based on second-harmonic generation. This method is broadband, passive, has low complexity, and suppresses noise uniformly over the noise spectrum. We theoretically model, analytically analyze, and numerically simulate this technique’s performance for CW and nanosecond pulse lasers with different pulse shapes. We demonstrate broadband relative intensity noise suppression of up to 48 dB, and pulse-to-pulse energy fluctuation suppression of up to 50 dB.

A compact high efficiency mid-IR detector based on sum frequency generation (SFG) in a straight intracavity structure is proposed and demonstrated. The intracavity setup was built upon a diode-pumped Nd:YVO4 crystal providing 1064 nm fundamental light and mid-IR signal beam at 3.46 microns was coupled into the cavity via a dichroic mirror. The nonlinear medium for SFG was a bulk 47.5 mm long MgO:PPLN crystal, which was used to generate near-infrared (NIR) light at 814.2 nm under the quasi-phase matching (QPM) condition where Mid-IR to NIR conversion efficiency as high as 32.4% has been achieved. The proposed technique provides a good linear response in conjunction with commercially available detection methods.

I would like to introduce a polarization-based entangled photon source that I built, suitable for satellite-based quantum key distribution.The source uses periodically-poled Lithium Niobate crystals to generate entangled photon pairs at wavelengths of 791nm (signal) and 1550nm (idler). An entangled photon source with high stability and robustness can be achieved by improving the photon interferometer that is necessary to make the correlated photon pairs. Beam splitters are commonly used optical devices in such interferometers. However, our team has devised with an alternative interferometer design which uses two beam displacers instead of the beam splitters. We also utilize nonlinear crystals to compensate for spatial and temporal walk-offs, further enhance the source performance. The performance has been verified, and we are about to make a next huge step by applying it to a satellite project called Quantum Encryption and Science Satellite (QEYSSat) in collaboration with Canadian Space Agency.

We present an experimental realization of the fractional nonlinear Schrödinger equation (FNLSE) in a fiber setup. Our focus is on spectral bifurcations, which link pulses with different numbers N of spectral peaks in the framework of FNLSE. Consistent with the theoretical model, the experiments demonstrate direct bifurcations 1→N at achievable nonlinearity levels, in contrast with the usual sequential scenario, 1→2→3 ...→N. The proposed model and experimental realization of FNLSE offer new possibilities for studies of fractional nonlinear optical phenomena.

Plasmonic resonators, formed by metal nanoparticles, have become a prominent topic in nanophotonics, partially due to their unique abilities of enhancing light-matter interactions. These structures exploit surface plasmons, and can yield electromagnetic modes that are well below the diffraction limit. This area of study provides a variety of fascinating real-world applications, including nano-lasing, sensing, and quantum technology. However, due to the inherently lossy nature of the metal in plasmonic resonators, these structures experience significant decay rates. Thus, an important goal in optical plasmonics is to determine ways in which these losses can be suppressed. Previously, the mode theories used to describe the optical response of metal nanoparticles were based on normal modes, but these were deemed problematic because of the lack of consideration of losses. Recently, accurate cavity mode theories have been formulated using "quasinormal modes", which are the formal solutions to the source-free Helmholtz equation, but with open boundary conditions. By using a quasinormal mode theory, it has become clear that cavity physics applies to plasmonic resonators, and offers advantages over all-numerical approaches as it is more efficient and lends itself to mode quantization. Using a rigorous mode theory for gain-compensated plasmonic dimers, we demonstrate how Purcell factors can be drastically increased, from 3000 to over 10 billion. Full three-dimensional calculations are presented for gold dimers in a finite-sized gain medium, which allows one to easily surpass fundamental Purcell factor limits of lossy media. With a linear system response, we show how Purcell factors are modified to include a contribution from the non-local gain. We also discuss how gain impacts superradiant and subradiant decay rates for coupled dipole emitters.

We report a compact difference frequency generation (DFG) intracavity structure emitting at 3.43 microns with greater than 100 mW output power. The device consists of a diode-pumped Nd:YVO4 cavity providing the 1064 nm pump light, and a C-band EDFA signal beam coupled into the cavity via a dichroic mirror. The pump and signal are combined in a 50 mm PPLN to generate mid-infrared light via quasi phase matching. The proof of principle prototype was previously published, but we have since improved the total output power and have a more developed prototype ready for professional packaging. We also present the theory and simulation work that led to the improvements and discuss future possible optimizations using insights from the modelling.

Through the application of the inverse Faraday effect (IFE), graphene can exhibit an optically-generated DC magnetization due to the nonlinear response of its orbital angular momentum to circularly polarized light. By providing a single-particle quantum mechanical model of this optomagnetic effect, we derive a non-perturbative analytical expression for magnetization based on dressed states of quasi-electrons in the Dirac region. Optical rotatory power is computed through gyroelectric birefringence where we predict measurable polarization rotation angles under moderate and intense optical radiation.

Near-room temperature operating semiconductor nanowires offer a promising platform for addressing high-performance demands in nano-optoelectronics. Here, we theoretically demonstrate a mode-matching technique can be utilized to couple free-space light into the fundamental mode of InP tapered nanowires. Through mode-matching and adiabatic coupling, we show a selective, wavelength-tunable method that achieves near-unity (≥99%) absorptance in a single tapered InP nanowire at a limit of light-matter interaction. Our results pave the way for the design of high-performance optoelectronic devices at the nanoscale.

Micro-optomechanical magnetic sensors define a promising area of research due to their small footprint and high sensitivity for sensing applications. This work presents a novel in-plane Lorentz force magnetometer based on a photonic crystal directional coupler with high in-plane sensitivity in a small mode volume. Previous work in our group has focused on an out-of-plane magnetometer that faced issues with thermo-mechanical forces and buckling affecting the vertical displacement and sensitivity of the sensor. The device was redesigned to leverage the high in-plane sensitivity with additions of s-bend bridges and a differential pair to absorb vertical deformation and reject common mode noise respectively.

A novel MoS2 split-nanoring metasurface has been proposed to detect small bioanalytes such as viruses and bacteria. The impact of an odd and even number of MoS2 monolayers on resonance characteristics and sensing performance of the leaky nanoresonators are being presented

We hereby highlight a rapid, cost-effective method for a microfluidic chip fabrication tailored for nanoscale optical trapping applications. The combination of colloidal lithography, cutting of Parafilm, and thermal bonding presents a simple and effective process to trap and analyze single proteins in solution.

The commonly quoted saturation intensity of rubidium (Rb) for D2 transitions is 16.7 W/m^2. This value, however, is only accurate for the cycling transition, which renders the Rb atom to resemble a two-level system. In practice, the effective saturation intensity is influenced by various factors, such as the polarization of light, optical pumping, and atom collision which can redistribute the population. As a result, it is crucial to experimentally determine the effective saturation intensity. In this context, we demonstrate a novel yet simple experimental method to measure the effective saturation intensities of Doppler-broadened transitions in atomic vapours. Our method only requires on-resonance absorbance data for various input laser intensities, which can be obtained with a tunable CW laser without the need for precise frequency locking. We applied this method to measure the effective saturation intensities of all four Doppler-broadened D2 transitions in natural rubidium (Rb) vapour (27.8% 87Rb and 72.2% 85Rb) at T=35C. The results show that the effective saturation intensities for Rb range from 0.752 to 16.8 W/m^2. Notably, for certain transitions (specifically, repump transitions), the effective saturation intensities were smaller than 16.7 W/m^2 (up to an order of magnitude), with potentially important implications for optical pumping in Doppler-broadened transitions.

In this study, we explore the interaction between antenna near-fields and the electro-optical properties of thin film lithium niobate (TFLN) waveguide structures. Utilizing a unique experimental setup, we focus on the electromagnetic fields generated by antennas and their effect on TFLN waveguides. Our approach introduces a novel method for characterizing antenna arrays by examining the responses of optical waveguides. Specifically, we investigate the impact of a 30GHz patch antenna, a component of the antenna array, on the near-field of a TFLN fabricated Mach-Zehnder Interferometer (MZI) waveguide at a wavelength of 1550nm. The process of fabricating both the TFLN waveguide and the antenna unit is detailed, with empirical observations in simulations being corroborated by experimental results. Our findings indicate that activating the antenna with an input power of 20 dBm leads to a significant 2% reduction in the output power of the TFLN MZI waveguide, underscoring the waveguide's sensitivity to the antenna's electromagnetic field. This observed reduction is slightly less than the 5% decrease anticipated from our simulations, a variance attributed to experimental challenges and minor deviations in the fabrication process. Further testing shows that when the antenna input power is maintained below 10 dBm, the power variance at the waveguide output is less than 1%. These results confirm the potential of TFLN-MZI waveguides as sensitive detectors for changes in electromagnetic fields emitted by nearby antennas, paving the way for their application in the real-time diagnostics of antenna arrays.

Dynamic lenses made from soft stimuli responsive materials for smart imaging applications have become a growing field of research. These lenses induce quick and precise changes of material curvature and thus focal length. Here, we apply principles of non-linear light phenomena to this emerging technology. We describe a class of electroactive dynamic lens inscribed with complex light-guiding arrays (i.e. micron-sized waveguides), which will result in significantly enhanced field of view (FOV), as compared to lenses without waveguides.

In this work, we active the defect mode of a porous Si-SiO2 microcavity embedded with ZnO photoluminescent nanoparticles by means of a 350nm laser. ZnO nanoparticles were obtained by Sol-gel method and were placed over the porous surface of the microcavity by drop coating method. Optical properties and morphological were determinate employed UV-Vis-IR, SEM and photoluminescence spectroscopic. We found that the position and bandwidth of the photoluminescence spectrum corresponds to the active mode of the microcavity.

Pulsed laser deposition of 1–3 ML MoS2 on SiNx membranes and SiO2/Si 2-inch wafers. Stacking orientation of MoS2 is AA’ and AA’A’ with low rotation angle variation across samples. Uniform, large-area growth of MoS2 confirmed with transmission electron microscopy and, with μ-Raman and µ-PL measurements of 1–3 ML MoS2, obtaining values similar to the reported ones. Density functional theory study of the band structure and PL emission of 1ML and rotated 2ML MoS2, in close agreement with our experimental measurements.

We show the chalcogenide phase change alloy antimony sulfide (SbS) can be synthesized/deposited on various substrates through solution-processed techniques, removing the need for costly ultra-high vacuum physical vapor deposition (PVD). We show that non-volatile transitions (amorphous–crystalline) bring large optical contrasts with relatively low extinction coefficients across telecom frequencies with suppressed thermo-optic coefficients compared to films grown through PVD, making them ideal for use as low noise/drift synaptic weights and memory elements in emerging telecommunication and computing architectures.

We demonstrate an on-chip optical frequency comb generator using cascaded Mach-Zehnder modulators (MZMs) on silicon-on-insulator. We investigate the possibility of generating multiple frequency combs by exploiting the periodic response of MZMs and obtain a dual-wavelength comb, each with 9 comb lines and a frequency spacing of 10 GHz.

This work focuses on engineering gallium nitride nanowire based photonic crystal band structures, which ultimately leads to surface emitting UV lasing at various wavelengths.

An experimental and numerical study of the nonlinear optical properties of hibiscus sabdariffa in gelatin is shown. Using the Z-scan technique and a nm cw variable power Ar laser, nonlinear absorption was measured, which is the main contribution to the nonlinear refractive index. Hibiscus sabdariffa presents large phase changes at low powers, which causes spatial self-phase modulation (SSPM) effects. Our experimental results show a high agreement with the numerical model of thermal lens formation used.

The water effluents are usually charged by organic persistent pollutants which can lead to some environmental and health problems. To reduce the pollution due to organic products some treatment processes are available. Among them, we can cite filtration, flocculation, settling, sterilization or oxidation processes. Unfortunately, these processes are usually expensive, not easy to use and non-efficient. So these conventional treatments are not recommended for the organic pollution elimination. Advanced Oxidation Processes (AOP), which are based on hydroxyl radical (OH°), seems to be the most promising technologies to reduce the organic pollution. Photocatalysis is one of the AOPs processes where OH° radical is generated due to photo-excitation of a semi-conductor. OH° radical is a strong oxidant able to degrade most of the organic molecules. Thus heterogeneous photocatalysis can be considered as an interesting process to reduce organic and inorganic pollution on water effluent. The most used semi-conductors are TiO2 and ZnO. After a factor analysis, the RSM was realized to find the optimal conditions of the para-cresol photodegradation. The RSM graphs give a methodology which permit to predict the conditions for total para-cresol degradation for different parameters. The main objective of this study is to model and optimize the para-cresol photodegradation by UV/ZnO. The ZnO semi-conductor can be considered as an alternative to the most used photocatalyst TiO2. The DOE and CCD plan are used to approach the process degradation of para-cresol by UV/ZnO. Due to this, we are able to represent the influence of para-cresol concentration, photocatalyst concentration, agitation and UV intensity on the process performance. The interactions between the experimental factors and the optimal conditions can also be given. Some experiments were carried out to study the influence of some operating parameters. The process optimization of para-cresol degradation is thus highlighted. Different experimental operating conditions are studied. From a statistical point of view, some tests are necessary to evaluate the validity of the model as residual analysis, Fisher test, regression coefficient R2 and Student test. The variance analysis (ANOVA) is required to evaluate the validity of the model. Keywords: Photocatalysis, ZnO, para-cresol, eau, Central Composite Design (CCD)

This study examines the efficiency of grating couplers for connecting silicon on diamond (SOD) integrated waveguides to optical fibers. We begin by analyzing optimized uniform gratings and then apply linear apodization to boost efficiency. Apodization is used in two ways: over a partial segment of the grating, and over the complete grating. The research results highlight the effects of apodization on directionality, mode matching, and overall efficiency, offering insights for enhancing the performance of grating couplers in diamond photonics applications.

A closed form semi-analytical expression for the athermal design of bragg grating waveguides has been developed inspired by effective medium theory. Solving the band structure for such a periodic structure can be done by analytical methods, or by FDTD. In the former case, there exists solutions based on coupled mode theory, or transfer matrix theory to predict the band structure, yet these analytical methods may still require mode solution data to predict the band structure for a unique set of process parameters. With the latter method, it takes a long time to solve the band structure compared to the former. The time required to perform concept study for the athermal design of bragg gratings may be reduced using lookup table implementations of mode solutions and expressions based on effective medium theory with a mode confinement model.

Hall effect of light is a result of symmetry breaking in spin and/or orbital angular momentum (OAM) owning optical system. The angular momentum (AM) conservation law in the ensuing asymmetric system dictates redistribution of spin and orbital angular momentum, and is manifested in spin-orbit, orbit-orbit, and orbit-spin interaction/conversions and reorganization. This AM restructuring in turn requires shifts of the barycenter of the electric field of light. In the present study we show analytically and numerically how different electric field components are displaced upon tight focusing of an asymmetric light beam having OAM and spin. The relation between field components shifts and the AM components shifts/redistribution is presented too. We also demonstrate experimentally, for the first time, to the best of our knowledge, the spin-orbit Hall effect of light upon tight focusing in free space. This is achieved using azopolymers as a media detecting longitudinal component of the electrical field of light. These findings elucidate the Hall effect of light and may broaden the spectrum of its applications.

Here we present a rigorous study for the different integrated photonic platforms that can be used for on-chip refractive index (RI) sensing. The study includes the widespread silicon photonics platform, the silicon nitride platform and the silica platform. We compare these three platforms according to five parameters that determine the performance and reliability of the RI sensor. Finally, we conclude with the optimum platform for on-chip RI sensing according to the available technology and the aimed application.

Standard digital cameras are made with many individual photosites, all of which capture the intensity of light coming into the photosensors. These photosites have the innate ability to measure the intensity of light but not its wavelength. For this reason, color filter arrays are usually superimposed over camera sensors. The most common commercially available color filter array in cameras is known as the Bayer filter, and that has a unique filter arrangement with different proportions for red, green, and blue filters. Since Bayer filters block off some of the wavelengths it leads to extremely low overall light transmission from these absorptive color filters and results in the loss of ~75% incident light. Therefore, as an alternative approach to address these limitations, color splitters are introduced to split and redirect light into spatially separated pixels, and that will lead to avoiding these absorptive losses. Although, color splitters are promising to address the limitations of Bayer filters designing and optimizing these color splitters are unintuitive. Among different conventional optimization techniques, adjoint optimization has proven to be one of the most effective and promising approaches for nanophotonic inverse design as it is a gradient-based optimization technique that leads to efficient optimization. However, it is extremely computationally expensive, complicated to set up, and highly dependent on the initial conditions and for a single structure optimization, it requires hundreds of simulation runs. Moreover, the entire optimization procedure must be repeated if any simulation restrictions are changed. In this work we utilize Artificial Neural Networks (ANNs) to address most of these limitations as ANNs have been a transforming technique across numerous fields of research. Nevertheless, one of the major challenges in ANNs is that they require a reliable training dataset to train the network in order to perform better. Consequently, we present a hybrid strategy in this study, wherein we train the neural network on the adjoint-optimized dataset by merging both neural networks and adjoint optimization. In addition, we will tackle a fascinating problem in the machine-learning community: the possibility of extrapolating in generative networks while generating splitter structures having the same transmission performance inside the training region.

This work proposes a classifier model to support medical diagnosis without specialized intervention. Three methodologies for sample characterization were contrasted: original sample size, size homogenization by duplication, and homogenization by Data Augmentation techniques. Reaching a precision of 93% and an accuracy of 92%, models incorporating Data Augmentation techniques demonstrated superior performance.

Polarization second harmonic generation (P-SHG) imaging is a powerful technique for studying the structure and properties of biological and material samples. In this study, we present a novel method for accelerating P-SHG imaging by combining low-resolution imaging with deep learning image upscaling via Enhanced Super-Resolution Generative Adversarial Networks (ESRGAN) methods. We demonstrated that our method can significantly reduce the imaging time while preserving the accuracy and quality of the results.

An inverse design approach to pursue Bound States in the Continuum (BIC), at a specified wavelength, in all-Dielectric metasurfaces is proposed using Deep Reinforcement Learning (Deep-RL) algorithm. The method is time efficient, and muti-objective optimization is presented. To demonstrate, a Si split ring is designed in the Fiber-optic communication band that shows a symmetryprotected BIC at a wavelength of around 1580 nm.

We report inverse-designed nonlocal metasurfaces for transforming multidimensional states of light represented in the Hermite-Gaussian basis into optimally designed spatial states, where a simple imaging can accurately extract the full multidimensional state including amplitude, phase, and coherence.

Using a region-specified residual convolutional neural network, we design a variety of nanostructures with desired scattering and absorption responses. This technique allows for single-shot training over different wavelengths of interest and is especially suitable for realizing narrowband responses and/or localized tuning of the response. In this context, we will discuss the impact of the quality of the training dataset on the accuracy of the results over different wavelength regions.

We present a smart approach to tailor stable microcombs within microring resonators by employing genetic algorithms to target distinct comb regimes and locate the experimental parameters that enable their generation. Our approach allows for the repeatable reproduction of the targeted microcomb states, with power-per-line stability of over one day and spectral coherence of ~86% for three photon lifetimes.

We study the spectroscopic properties of light-emitting diodes (LEDs) and the use of machine learning to analyze the spectral data. Computer programs with different algorithms are evaluated and compiled. Assessment is performed on the selection of program language and platform, optimization and verification of the effectiveness. Further exploration on the improvement in the analysis of spectral data with machine learning techniques is discussed.

We propose and investigate the transmission performance of a DP-16-QAM signal based underwater optical wireless communication (UOWC) link. 112 Gbps information is transmitted over a single-laser channel along 10 m UOWC range under pure sea environment with acceptable bit error rate (BER) and constellation of the received signal. Digital signal processing (DSP) algorithms are employed to enhance the quality of the received signal.

We design and evaluate the transmission performance of an inter-satellite optical wireless transmission system based on mode division multiplexing (MDM) of Laguerre-Gaussian (LG) beams. 80 Gbps information is transmitted over a single-laser channel along 12000 km inter-satellite range with acceptable bit error rate (BER) and eye-diagrams of the received signal.

We model squeezed state generation in a lossy optical cavity in the presence of a thermal bath. We show that the exact solution is a squeezed thermal state, where thermal photons arise both from loss and the thermal bath. We model squeezing for a continuous wave pump below and above the critical pumping threshold.

We showed that the sinisterness of state, which quantifies the correlation between bipartite systems, can be used to determine the effectiveness of arbitrary mixed separable initial states in performing ancilla-assisted process tomography(AAPT).

We comprehensively studied the architecture and link budget of a cryogenic photonic readout circuit designed for radio frequency (RF) qubits. We start by outlining the motivation for an optical readout link, followed by an examination of the architectural choices and a through link budget analysis. We conclude by simulating the entire link under noisy conditions, demonstrating its feasibility in quantum computing applications.

We use time-resolved optical spectroscopy and ultrafast electron diffraction to capture the motions that couple to the reaction trajectory of a photo-induced formation of chemical bond in a carefully designed dimetallic Platinum complex.

Fiber-optic strain gauges, unlike conventional electrical strain gauges, are passive sensors which are immune to electromagnetic interference (EMI). This permits the sensor to be used in harsher environments, but often requires the sensor to work over long fiber tether lengths. Previously this has been achieved using distributed sensing measurements which rely, typically on Brillouin scattering to detect and localize strain. Highly localized or point sensing is more appropriate for acoustic (hydrophone) measurements and submarine equipment monitoring and can be achieved using a compact transducer, typical a Fiber Bragg Grating (FBG) or equivalent, which exhibit a resonance peak/dip in the reflection spectrum when interrogated by a laser. This peak shifts linearly when strain is applied to the grating. We present a passive, all-fiber strain sensing system capable of measuring strain over 75 km using a diode laser locked to a π-shifted grating. The highly local strain measurement is extracted from the feedback signal sent to the laser for frequency stabilization, thereby reducing the baseline acoustic noise level for longer tethers. The system was locked through 75 km of fiber and strain was measured at 10 Hz with a sensitivity of 5.27 mV/με and a minimal detectable strain of 67 nε.

In this study, we delve into optimizing optical quantum swap gate designs, which are crucial in the advancement of quantum computing. Using qINTERCONNECT, we conduct a comparative analysis of swap gate designs, including those based on equivalent circuits like CNOT gates and others utilizing dedicated architectures. Our aim is to compare the balance between operational efficiency and error tolerance in these varying designs, so as to measure their potential for scalability. Through simulations grounded in real-world fabrication parameters, we assess the fidelity and success probabilities of each design approach. Our findings indicate that while equivalent circuit-based designs are traditionally favored in other fields of quantum computing, dedicated swap gate architectures may offer enhanced robustness and scalability in optics. This study provides a comparative understanding of different swap gate designs, elucidating the relative merits and drawbacks of current designs, and offering insights that are relevant for practical applications in quantum computing.

We present schemes to implement a universal set of quantum gates based on experimentally achievable interactions. The gates can be protected against decoherence through a dynamical-decoupling approach. Some of the gates are also robust against the imprecisions in controlling system parameters. The desired interactions can possibly be realized in superconducting circuits and trapped ions with controllable system parameters.

The Reference-Frame Independent Quantum Communication for Satellite-Based Networks (ReFQ) project, launching on board the Canadian Quantum Encryption and Science Satellite (QEYSSat), aims to test the feasibility of space-to-ground Quantum Key Distribution (QKD) using a quantum source and novel QKD protocol. To prepare for launch, a testbench setup that simulates various phenomena ReFQ will experience on flight has been developed. This allows the module to be tested in satellite-like conditions in a full end-to-end demonstration, providing crucial insight for optimization, testing theoretical predictions, and ensuring readiness for flight.

We propose a time-resolved optical measurement scheme for sampling transient ther- mal currents inside a bulk centrosymmetric semiconductor. The technique relies on spontaneous emission of second harmonic light, triggered by four-wave mixing between a pulsed below-gap opti- cal excitation and a spontaneous intraband polarization. This all-optical technique requires neither contact nor bias fields, making it an innovative experimental method for exploring thermal and quantum fluctuations in the solid state in a non-invasive manner. Theoretical estimates bracket signal in the range of 10−4 to 10−2 relative to the shot noise of the probe, motivating experimental implementations of the proposal.

In this study, we discuss two approaches to implement CNOT gates in Ytterbium (Yb)-doped yttrium orthosilicate (YSO) crystals. We examine magnetic dipolar interactions and virtual photon exchange as non-cavity and cavity-mediated schemes, respectively. We compute the gate fidelity of each scheme considering the most important imperfections facilitating a comparison of physical advantages between the two proposed gate schemes.

Applications across photonics require transforming optical spatial modes. We experimentally demonstrate general transformations on a two-beam array in a reconfigurable setup.

Free-space optical quantum communications major drawback arises from the effect of atmospheric turbulence on the encoded message. Recent studies have demonstrated the effectiveness of implementing an Adaptive Optics (AO) system in the detection stage of a free-space link to compensate for the wavefront distortions. In this work, we focused on the implementation of different photonic spatial modes to encode information for our communication protocols. The results of this study allow us to obtain information regarding the advantages and limitations of our system.

We develop a theoretical model for cavity-enhanced atomic frequency comb (AFC) quantum memory that includes the effects of dispersion and show a close alignment of the model with our own experimental results. Our model is a step forward to accurately estimating the created comb properties, such as the optical depth inside the cavity, and so being able to make precise predictions of the performance of the prepared cavity-enhanced AFC quantum memory.

Research on MZI (Mach Zehnder Interferometer) TOPS (Thermo-Optic Phase Shifter) often focuses on improving performance in terms of power consumption, switching time, and reducing crosstalk. Differential control methods have been proven to be useful in lowering the switching time with a tradeoff of higher input power. This work focuses on facilitating differential control of TOPS to reduce both rise and fall time, leveraging thermal crosstalk to optimize switching speed, power dissipation and device footprint. Simulation results show that further modification in design and control will deliver a competitive solution.

Exploring thin films of chloro-aluminum phthalocyanine (AlClPc), this study delves into the optical characteristics of samples fabricated through the thermal evaporation method at varying substrate temperatures. The deposition process spans a range from room temperature to 250°C. Interestingly, the transmittance measurements exhibit resilience to fluctuations in substrate temperature during deposition. The reflective and absorptive tendencies mirror the behavior observed in transmittance, showcasing a consistent pattern. Notably, alterations in substrate temperature exert a discernible influence on optical constants such as the refractive index (n) and extinction coefficient (k). Furthermore, an exploration of solar and photopic parameters reveals nuanced outcomes across different substrate temperatures. Curiously, the absorption coefficient appears impervious to changes in substrate temperature throughout the deposition process. This divergence challenges conventional expectations, offering a unique insight into the optical behavior of chloro-aluminum phthalocyanine thin films under varying thermal conditions.

With threading dislocation densities a few orders of magnitude lower than the epitaxial counterparts, bulk Ge crystals stand out as ideal materials for investigating the performance potential of Ge lasers. In this work, we demonstrated that the photoluminescence (PL) peak intensity of 535 µm thick bulk Ge can be increased by 36 times by reducing the thickness to 2 µm by wet etching. Due to the much higher Ge quality, the PL peak intensity of the 2-µm-thick bulk Ge sample with a 1016 cm-3 n-doping is three times that of a 0.75-µm-thick epitaxial Ge with a 1019 cm-3 n-doping, showing the high effectiveness of bulk Ge-based thin films in light emission applications.