In emerging technologies such as smartphones and smart windows, flexible and transparent miniaturized energy storage systems are essential, yet existing devices often fail for practical applications. To address this, a plasmon-assisted strategy is employed to enhance microsupercapacitor (MSC) performance by incorporating silver nanowires into a ZnO-based transparent device on a flexible polydimethylsiloxane (PDMS) substrate. The MSC exhibits outstanding electrochemical performance, achieving a volumetric capacitance of 996.73 F cm-3, an energy density of 138.43 mWh cm-3, and a power density of 1.74 W cm-3 under combined plasmonic excitation and photoirradiation, ∼50% enhancement relative to the dark condition. The silver nanowires act as plasmonic hot spots that promote redox activity through plasma induced resonance energy transfer (PIRET), which is also confirmed by finite-difference time-domain (FDTD) simulations. The platform harvests sunlight and hydrovoltaic energy to power an LED for 90 s, demonstrating potential for next-generation flexible, transparent microscale energy storage systems.

SnTe is an intriguing thermoelectric (TE) material that offers a promising alternative to its toxic Lead-based counterparts. Herein, we demonstrated the energy filtering of the charge carriers in SnTe thin films by incorporating Au nanoparticles (NPs) in SnTe-Au nanocomposite system. The embedded Au NPs introduces band bending potential at the SnTe/Au heterojunction that enables the scattering of low energy holes of the SnTe thin films. The Kelvin force probe microscopy measurements were performed to investigate the charge transport at the SnTe/Au heterojunction. The filtering of low energy holes ultimately leads to a significant improvement in the TE power factor of the nanocomposite samples. A remarkably high-power factor of 25.27 μW/cm-K2 and 79.53 μW/cm-K2 was achieved by incorporating 0.6 at% of the Au NPs at 300 K and 675 K, respectively. Further, the pronounced scattering of phonons by incorporated Au NPs dramatically reduces lattice thermal conductivity, resulting in the high near-room temperature zT of ∼0.25 at 350 K. This work opens a new paradigm for development of a non-toxic and high-performance TE materials by tailoring the transport properties at metal-semiconductor heterojunction.

Nanostructured photonic architectures enable precise control of light-matter interactions through field confinement and optical resonances, enabling high-performance optoelectronic devices. At the same time, metal halide perovskites have emerged as a promising photoactive material for these devices due to their excellent optoelectronic properties. In this perspective, we report a hybrid photonic perovskite platform by integrating dual-phase CsPbBr3-CsPb2Br5 nanosheets with a TiO2-coated two-dimensional (2D) photonic array for enhanced photodetection and directional light emission. This configuration offers Guided Mode Resonance (GMR) enhanced optical absorption and electric-field confinement within the perovskite layer. The hybrid photodetector exhibits an enhanced photocurrent, increasing from 3 nA for the planar device to 40 nA for the array-integrated device at 405 nm laser excitation, resulting in a 1000% enhancement factor and a light-on/off ratio of around 103. Additionally, the hybrid device exhibits a maximum responsivity of 25.0 mA/W and a detectivity of 6.0 & times; 109 Jones at the resonant GMR wavelengths, underscoring the effectiveness of guided-mode-assisted field confinement. Furthermore, the designed photonic array exhibits enhanced directional emission, a 10-fold increase in emission intensity, and a Purcell factor of 2.27 by coupling the spontaneous emission from CsPbBr3-CsPb2Br5 excitons to the GMR modes supported by the array. These findings establish a scalable, low-loss strategy for integrating photonic-perovskite architectures into the development of advanced optoelectronic devices.

Structured Illumination Microscopy (SIM) enables super-resolution imaging by encoding high-frequency spatial information through patterned light. While traditional Fourier-based reconstruction methods are prone to artifacts under suboptimal conditions, recent deep learning approaches often require large training datasets and lack adaptability across different imaging setups. In this work, we present Position Encoded Multi-Layer Perceptron (PEM) network that leverages implicit neural representations (INRs) and SIM forward-model-driven modeling to reconstruct super-resolved images without any training data. PEM-SIM represents each spatial coordinate as a combination of sinusoidal functions across multiple frequencies, enabling rich encoding of fine spatial detail. A forward model grounded in SIM image formation principles is then used to iteratively optimize reconstructions by minimizing the structural similarity loss between the generated images and the acquired SIM data. We demonstrate that PEM-SIM reconstructs both 2D and 3D SIM images with fewer input frames than conventional methods and successfully predicts missing axial planes in 3D stacks. The method shows robustness across varying signal-to-noise ratios and performs comparably to standard algorithms on both synthetic and experimental datasets. By eliminating the dependency on large datasets and enabling flexible, high-resolution reconstructions, PEM-SIM offers a data-efficient alternative for super-resolution imaging in microscopy.

This study presents an analytical model for fluorescence modulation in fluorescence-detected mid-infrared photothermal microscopy. Pulsed mid-infrared (MIR) lasers induce molecular vibrational absorption in targeted chemical bonds within biological samples, resulting in localised temperature changes that modulate the fluorescence intensity of nearby thermosensitive dyes. By detecting these intensity variations under visible light pulsed laser excitation, the technique facilitates high-resolution infrared spectroscopy and chemical imaging in living cells. The temperature rise is influenced by factors such as the size and thermal properties of the absorbing sample, pulse width, interpulse delay, and wavelength-dependent absorption. To predict the temperature rise and the corresponding fluorescence modulation, we developed an analytical model that combines Mie scattering and a lumped thermal model to capture temperature dynamics during and after pulsed MIR excitation. The simulated fluorescence signals were validated experimentally at a MIR wavelength of 9.74 mu m using 1 mu m polystyrene beads. The simulation accurately matched the measured modulation contrasts within 6%. This model provides a framework for optimising F-MIP microscopy for high-resolution chemical imaging.

Structured illumination microscopy (SIM) is a powerful widefield nanoscopy technique known for enhancing resolution by $\sim 2$-fold. Despite various advancements aimed at pushing its resolution limits, achieving high resolution across a large field of view (FOV) remains a significant challenge. In this work, we introduce a tilt-mirror-based multi-periodic SIM (mMP-SIM) approach that enables super-resolution imaging over a wide area. This method utilizes six-beam interference patterns, generated via a specially designed mirror mount, to illuminate the sample with multi-periodic structured light. Using a $20 X / 0.40$ numerical aperture objective lens, we demonstrate a 3.16-fold resolution enhancement across a large-FOV $\left(0.53 \times 0.34 \mathrm{~mm}^{2}\right)$. This represents a 9.98-fold improvement in space-bandwidth product, addressing key limitations in large-area imaging. Furthermore, by decoupling the illumination and detection pathways, mMPSIM offers scalability for high-resolution imaging across extended areas. With a $28 X / 0.80$ NA objective, we achieve an optical resolution of 170 nm over a $(0.40 \times 0.25) \mathrm{mm}^{2}$ area. The system’s capabilities are validated through experiments on both for fluorescent beads as well as bio-sample like U2OS (human bone osteosarcoma) cells.

High-resolution imaging techniques have revolutionized the observation and analysis of features or structures across various disciplines, including nanotechnology, material science, and biomedical imaging. Stimulated emission depletion (STED) microscopy is a groundbreaking super-resolution imaging approach that overcomes the diffraction limit of traditional microscopy techniques, enabling visualization of nanoscale sub-cellular characteristics with remarkable resolution and precision. However, the requirement of precise alignment of multiple laser beams, the use of complex and bulky optical system, and high operational costs make the system challenging, difficult to maintain and less accessible. Development of high-performance, ultracompact, lightweight optics is thus necessary to realize a robust, efficient and accessible high-resolution optical system. Here, a single-layer dual-wavelength polarization multiplexed metalens that shapes the depletion beam and achieves achromatic focusing of the excitation and depletion beams in orthogonal polarization states at the focal plane for STED microscopy is proposed. The optical performance of the metalens at the focal plane is characterized, and the achievable resolution is numerically calculated. Leveraging the benefits of planar and ultracompact architecture, high integrability, the proposed metasurface-based approach establishes a stable single-beam STED microscopy system that can democratize super-resolution imaging, therefore expanding accessibility and applicability across various scientific domains.

The early detection and diagnosis of diseases are of paramount importance for effective healthcare outcomes. Serum albumin is an important biomarker for many diseases. A reduction in albumin can be noted in various diseases, rendering it an important marker for assessing disease progression and treatment efficacy. To get accurate readings of these biomarker levels, we need methods that are very sensitive, reliable, quick, and non-invasive. Optical phase detection techniques exhibit high sensitivity, convenient readout strategies, and low limit of detection (LOD) in comparison to other detection methods. Here, we demonstrate a new phase detection mechanism employing a Fresnel biprism in conjunction with resonantly enhanced phase sensitivity achieved by using guided mode resonance (GMR). These elements are combined into a compact and bench-top common-path phase-detection system that can be realized with very few low-cost components. The common-path configuration effectively mitigates mechanical vibrations typically associated with two-beam interferometry used for phase detection. To demonstrate the capability of our approach, we designed and fabricated a GMR-based instrument and used it to detect bovine serum albumin (BSA) at different concentrations. The stability of the setup was instrumental in detecting BSA concentrations as low as 1 pg/mL.

Utilizing fluorescent emitters with precisely designed nanostructures regulates their emission characteristics, which has great potential in light-emitting devices, biosensing, and quantum technologies. In this context, we propose a large area nanostructured design on a flexible polyethylene terephthalate (PET) substrate by patterning it in a square periodic symmetry and coating it with a TiO2 thin layer to demonstrate cost-effective photoluminescence enhancement and directionality. The proposed design enables a controlled light emission enhancement of about 110 times from the emitter layer over the array through resonance-mediated light confinement. Such mode confinement leads to an increase in the local density of states, which leads to a 100-fold increase in the Purcell factor. Beyond amplification, the polarization-dependent excitation of GMR modes enables directional coupling of photoluminescence into the radiative zeroth-order channel, resulting in well-defined angular emission profiles, as validated by angle-resolved spectroscopy and back focal plane imaging for both transverse electric and transverse magnetic polarization of incident light. The proposed large-area photonic array on a PET substrate offers potential for incorporation into advanced light-emitting optical devices, owing to its scalability and adaptability for practical applications.

This study introduces a novel approach to design and enhance the diffraction efficiency of polarizationindependent multilayer dielectric gratings, which are utilized for spectral beam combining in off-Littrow configurations. The key challenges associated with using polarization-independent multilayer dielectric gratings in off-Littrow setups are addressed, with the modal method employed to highlight the necessity of tapering grating structures during optimization. The design process involves the selection of optimal grating parameters and incidence angles for individual lasers in spectral beam combining. The rigorous coupled-wave analysis combined with particle swarm optimization is used to compare the average diffraction efficiency of three different types of polarization-independent multilayer dielectric grating designs, optimized in both Littrow and off-Littrow configurations. The proposed design achieves 97.85% average diffraction efficiency, with a minimized grating aspect ratio of 1.65, making it highly suitable for spectral beam combining applications. Furthermore, tolerance analysis of the gratings summarized that the proposed design exhibits the highest tolerance range among the evaluated configurations, ensuring robustness against fabrication-related deviations.

The plasmonic integrated semiconductor has widened the operational spectral region of semiconductors for light-matter interaction-driven solar energy harvesting applications. However, a specific plasmonic resonance has moderate light absorption and is only active in a specific width of the visible spectrum. We present a tailored plasmonic particle grating-based Au-TiO2 Schottky photoelectrode-based broadband absorber that operates in the extended spectral region of 400-800 nm due to the synergistic interaction of multi-resonant photonic and plasmonic modes of the plasmonic particle grating structure. In the visible spectrum, the proposed photoelectrode increased the incoming photon to electron conversion efficiency (IPCE%) by seven and five times more than TiO2 for TM (along the grating vector) and TE (perpendicular to the grating vector) incidence, respectively. The plasmonic response of the gold nanoparticle and the grating-coupled surface plasmon polariton (SPP)-guided mode resonance (GMR) are responsible for such increments. Ultrafast pump-probe spectroscopy verifies that the plasmon-GMR interaction causes extended plasmonic charge generation and lifetime. The kinetics of plasmonic-generated charges in grating-coupled SPP and LSPR was investigated through TM and TE polarized pump and probe excitation. Such findings are consistent with the observed PEC spectral responses under their respective polarization illumination. Therefore, our research provides a simple method for integrating photonic and plasmonic materials for innovative broadband spectrum responses in photovoltaic and energy harvesting applications.

Structured illumination microscopy (SIM) is a robust wide-field optical nanoscopy technique. Several approaches are implemented to improve SIM's resolution capability (∼2-fold). However, achieving a high resolution with a large field of view (FOV) is still challenging. We present tilt-mirror-based multi-periodic SIM for large-FOV super-resolution microscopy. The sample is illuminated by a multi-periodic structured pattern generated by six-beam interference using a custom-designed mirror mount. We achieve 3.16-fold resolution improvement while using a 20×/0.40 numerical-aperture objective that supports a large FOV (0.53 mm × 0.34 mm). This overcomes the high-space-bandwidth product challenge, achieving 9.98-fold improvement. mMP-SIM decouples illumination and collection paths, enabling scalable super-resolution over a large FOV. By using a 28×/0.80 numerical-aperture objective lens, an optical resolution of 170 nm over a 0.40 mm × 0.25 mm imaging area is demonstrated. The proof-of-principle experimental demonstration is performed for both fluorescent beads and a biosample like U2OS (human bone osteosarcoma) cells.

All optical information processing and identification enables high speed, low power consumption, and efficient complex data processing. Optical edge enhancement can extract structural and morphological information about an object; however, existing systems require bulky and complex optical configurations. Development of a low-cost, lightweight, integrable, and high-performance imaging system is thus necessary for biomedical and industrial applications in the field and onsite. Here we propose and demonstrate a compact metasurface imaging system composed of cascaded metasurfaces that function as a metalens and q-plate for isotropic edge enhancement of amplitude objects, phase objects, and biological specimens. Furthermore, we utilize the polarization degree of freedom of light in addition to amplitude and phase to achieve anisotropic edge enhancement. By utilizing different polarization states of incident light, the impulse response of the metasurface imaging system is modified to achieve real-time isotropic and directional edge enhancement while maintaining a field of view. The proposed approach demonstrates a robust, ultracompact, lightweight, efficient, and integrable platform for reliable, stable, and cost-effective point of care devices, process control, and monitoring.

We propose a novel super-resolution microscopy technique, named absorption modulation-based non-linear structured illumination microscopy (AM-NLSIM), by utilizing the photochromic properties of a material, specifically azobenzene chain polymers. In the proposed technique, dual-wavelength sinusoidal illumination interacts with a layer of photochromic molecules, referred to as an absorption modulation layer. This interaction generates a non-linear illumination pattern encoding additional high-frequency components within the system's passband. We present the theoretical foundation of AM-NLSIM, supported by numerical simulations. Simulations are performed on different samples, where the captured Moir & eacute; frames undergo a blind reconstruction approach tailored for non-linear SIM. The simulations demonstrate the utility of AM-NLSIM to achieve sub-50 nm resolution based on computer-generated images while maintaining the practicality of conventional linear SIM, i.e. using low-intensity, continuous-wave lasers and standard fluorophores.

This study presents a cost-effective approach to implement the guided mode resonance (GMR) sensors for refractive index (RI) measurements. A silicon nitride (Si3N4) GMR chip, fabricated using e-beam lithography and incorporating an in-house diffraction grating, is integrated with a low-cost CMOS sensor for optical readout. This system effectively detects variations in the GMR output corresponding to RI changes. Experimental results demonstrate a sensitivity of 2.02 mm RIU-1, derived from the linear regression slope of the CMOS intensity spot position against RI variations. This innovative combination of GMR and CMOS technologies not only reduces costs but also significantly simplifies the detection mechanism, opening new possibilities for optical sensing applications.

We explore guided-mode resonant (GMR) structures in an unconventional way for low-cost yet effective bio-sensing applications. In contrast to regular broadband source-based wavelength interrogation techniques, single wavelength-based measurements can successfully eliminate the requirement of a costly spectrometer for rapid label-free detection and analysis. We have fabricated a silicon-nitride grating-waveguide structure and investigated it theoretically as well as experimentally under normal, angular, and conical incidences following an all-in-one transmission geometry. Such studies avoid unnecessary fabrication of multiple chips and promote a wide operational range of the GMR sensor. To validate the proposed cost-effective intensity-based sensing, we have analyzed our fabricated single GMR chip under different combinations of two-axis rotation to confirm its suitability under commonly available laser sources. Finally, using a He-Ne laser, a sensitivity of similar to 166 mW/RIU is recorded experimentally on an average for the fabricated GMR device, operating at the resonant wavelength of 632.8 nm. The current study provides an in-depth investigation to promote possibilities for utilizing GMR structures in an inexpensive intensity-based bio-detection scheme through the demonstrated proof-of-concept.

We demonstrate a single-shot digital holographic microscopy technique to improve the diffraction-limited resolution in two orthogonal orientations simultaneously by dual-channel orthogonal polarization multiplexing approach. Orthogonally polarized two oblique beams are employed to illuminate the sample and two reference beams with mutually orthogonal polarization are interfered with the object beams in a custom-designed Mach–Zehnder configuration. This technique is potentially beneficial to encode high frequency sample information from two orthogonal directions simultaneously in a single recorded hologram where the high frequency spectra is synthesized by the selective spectral stitching. Thus, the resolution is enhanced along two orientations from a single-shot hologram in this work. Both the simulation and experimental results are shown for the proposed technique with around 2-fold resolution enhancement over the diffraction limit.