The performance of infrared photodetectors has been shown to benefit from the application of plasmonic structures. While successful experimental implementations of optical engineering structures in HgCdTe-based photodetectors exist, they are not commonly reported. This study presents a plasmonically integrated infrared HgCdTe photodetector. The device incorporating a plasmonic structure demonstrates a unique narrowband effect in its experimental results, achieving a peak response rate near 2 A/W, a substantial 34% improvement compared to the reference device's performance. The simulation results are substantiated by the experiment, and an analysis of the plasmonic structure's impact is provided, demonstrating the indispensable role of the plasmonic structure in the device's improved performance.
This Letter introduces a new imaging technology, photothermal modulation speckle optical coherence tomography (PMS-OCT), for non-invasive and highly effective high-resolution microvascular imaging in living subjects. To improve the imaging contrast and quality in deeper regions compared to Fourier domain optical coherence tomography (FD-OCT), the method boosts the speckle signal of the blood flow. Simulation experiments demonstrated that the photothermal effect could both disrupt and amplify speckle signals. This effect manipulated the sample volume, altering tissue refractive indices, and consequently modifying the interference light's phase. Consequently, a change will be observed in the speckle signal reflecting the blood's movement. Employing this technology, we acquire a non-destructive, clear cerebral vascular image of a chicken embryo at a specific imaging depth. This technology, notably in the context of complex biological structures like the brain, significantly extends the utility of optical coherence tomography (OCT), introducing, as far as we know, a novel application in brain science.
We propose and demonstrate the performance of deformed square cavity microlasers, showcasing highly efficient output through an interconnected waveguide. The substitution of two adjacent flat sides with circular arcs within square cavities results in an asymmetric deformation, subsequently manipulating ray dynamics and enabling light coupling to the associated waveguide. Careful design of the deformation parameter, employing global chaos ray dynamics and internal mode coupling, allows numerical simulations to reveal the efficient coupling of resonant light to the fundamental mode of the multi-mode waveguide. Mocetinostat nmr The experiment demonstrated a significant increase in output power, around six times higher than that of non-deformed square cavity microlasers, coupled with an approximate 20% reduction in lasing thresholds. A highly unidirectional emission pattern, as observed in the measured far-field, aligns closely with simulation predictions, signifying the viability of deformed square cavity microlasers for practical implementations.
We present the generation of a 17-cycle mid-infrared pulse with passive carrier-envelope phase (CEP) stability, achieved by adiabatic difference frequency generation. Solely through material-based compression, a 16 femtosecond pulse with a duration of less than two optical cycles was realized, at a central wavelength of 27 micrometers, and manifested a measured CEP stability below 190 milliradians root mean square. genetic cluster The characterization of the CEP stabilization performance of an adiabatic downconversion process, to the best of our knowledge, is undertaken for the first time.
A simple optical vortex convolution generator, the subject of this letter, utilizes a microlens array as the optical convolution element and a focusing lens to obtain the far-field vortex array from a single optical vortex. The optical field distribution, positioned at the focal plane of the FL, is scrutinized both theoretically and experimentally using three MLAs of diverse sizes. In the experiments, the self-imaging Talbot effect of the vortex array was observed in addition to the results generated by the focusing lens (FL). Investigation also encompasses the generation of the high-order vortex array. The method's inherent simplicity and superior optical power efficiency enable it to generate high spatial frequency vortex arrays from devices with lower spatial frequencies. This method shows great promise in applications such as optical tweezers, optical communication, and optical processing.
A tellurite microsphere is experimentally used to generate optical frequency combs, for the first time, to our knowledge, in tellurite glass microresonators. The TeO2-WO3-La2O3-Bi2O3 (TWLB) glass microsphere displays a maximum Q-factor of 37107, exceeding all previously reported values for tellurite microresonators. A frequency comb containing seven spectral lines appears within the normal dispersion range when a 61-meter diameter microsphere is pumped at a wavelength of 154 nanometers.
Within a dark-field illumination setting, a fully immersed low refractive index SiO2 microsphere (or a microcylinder, or a yeast cell) allows for the clear distinction of a sample presenting sub-diffraction features. Microsphere-assisted microscopy (MAM) reveals a sample resolvable area that is segmented into two regions. The sample area lying beneath the microsphere is rendered virtually by the microsphere; the resulting virtual image is then received by the microscope. Directly imaged by the microscope is a region of the sample, specifically that surrounding the microsphere. The experimental results show a consistent correlation between the region of the sample surface with the enhanced electric field generated by the microsphere and the resolvable region. Through our studies, we've found that the heightened electric field generated on the sample's surface by the entirely immersed microsphere is a key element in dark-field MAM imaging, and this finding has implications for exploring novel resolution enhancement strategies in MAM.
In a variety of coherent imaging systems, phase retrieval is a fundamental and indispensable component. Traditional phase retrieval algorithms encounter difficulty in reconstructing fine details, as the limited exposure is amplified by the presence of noise. This letter details an iterative framework for noise-resistant phase retrieval, achieving high fidelity. The framework's approach of applying low-rank regularization enables us to investigate nonlocal structural sparsity in the complex domain, effectively preventing artifacts resulting from measurement noise. The optimization of both sparsity regularization and data fidelity, accomplished by forward models, results in satisfactory detail recovery. By means of developing an adaptive iteration strategy, we augment computational efficiency by dynamically altering the matching frequency. The efficacy of the reported technique in coherent diffraction imaging and Fourier ptychography has been verified, exhibiting a 7dB higher average peak signal-to-noise ratio (PSNR) compared to traditional alternating projection reconstruction.
The field of holographic display, a promising three-dimensional (3D) display technology, has been subject to extensive and diversified research efforts. Nevertheless, the real-time holographic display for live scenes remains a significant technological hurdle to widespread use in daily life. Further progress in the speed and quality of holographic computing and information extraction is essential. infection (neurology) In this paper, a real-time holographic display, operating on real-time scene capture, is presented. The system collects parallax images, and a CNN is used to establish the hologram mapping. Parallax images, captured concurrently by a binocular camera, include the depth and amplitude data essential for the process of 3D hologram generation. A CNN trained on datasets containing parallax images and premium-quality 3D holograms has the capability to convert parallax images into 3D holographic models. Optical experiments conclusively demonstrate the effectiveness of the static, colorful, speckle-free real-time holographic display derived from the real-time capture of actual scenes. By leveraging simple system composition and cost-effective hardware, the proposed method overcomes the challenges of existing real-scene holographic displays, creating a new avenue for real-scene holographic 3D display applications, such as holographic live video, while addressing the vergence-accommodation conflict (VAC) problem in head-mounted displays.
This letter reports on a three-electrode, bridge-connected germanium-on-silicon (Ge-on-Si) avalanche photodiode (APD) array compatible with the complementary metal-oxide-semiconductor (CMOS) fabrication process. Apart from the two electrodes situated on the silicon substrate, a supplementary electrode is engineered for germanium. An individual three-electrode APD underwent detailed testing and analysis for performance evaluation. Application of a positive voltage across the Ge electrode leads to a reduction in the device's dark current and a corresponding improvement in its response. At a constant dark current of 100 nanoamperes, germanium's light responsivity is observed to escalate from 0.6 amperes per watt to 117 amperes per watt as the voltage increases from 0 volts to 15 volts. This is the first reported near-infrared imaging study, to the best of our knowledge, of a three-electrode Ge-on-Si APD array. The device's functionality extends to LiDAR imaging and low-light detection, as evidenced by experimental studies.
Ultrafast laser pulse post-compression techniques often encounter significant limitations, such as saturation effects and temporal pulse disintegration, particularly when aiming for high compression ratios and extensive spectral ranges. To circumvent these constraints, we leverage direct dispersion management within a gas-filled multi-pass cell, thereby, for the first time in our knowledge, achieving a single-stage post-compression of 150 fs pulses and up to 250 J pulse energy from an ytterbium (Yb) fiber laser to a sub-20 fs duration. Large compression factors and bandwidths in nonlinear spectral broadening are obtained using dispersion-engineered dielectric cavity mirrors, with self-phase modulation as the main contributor, maintaining 98% throughput. A single-stage post-compression route for Yb lasers, enabling few-cycle operation, is enabled by our method.