Infrared photodetector performance has been demonstrably augmented by plasmonic structure implementation. Despite the potential for incorporating these optical engineering structures into HgCdTe-based photodetectors, actual successful experimental demonstrations remain comparatively scarce. We detail a plasmon-integrated HgCdTe infrared photodetector in this paper. The experimental investigation of the plasmonic device highlights a pronounced narrowband effect. A peak response rate of approximately 2 A/W was observed, exceeding the reference device's rate by nearly 34%. 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.
To facilitate non-invasive and effective high-resolution microvascular imaging in living subjects, this Letter introduces a new method: photothermal modulation speckle optical coherence tomography (PMS-OCT). This innovative technology enhances the speckle signal of the blood to improve contrast and image quality, especially at depths surpassing those attainable using Fourier domain optical coherence tomography (FD-OCT). Photothermal effects, as evidenced by simulation experiments, were found to influence speckle signals, both positively and negatively. The modification of sample volume, including changes in tissue refractive index, directly led to shifts in the phase of interfering light. Consequently, a change will be observed in the speckle signal reflecting the blood's movement. A clear, non-destructive image of the cerebral vascular system of a chicken embryo is produced at a particular imaging depth by means of this technology. This technology increases the usability of optical coherence tomography (OCT), mainly in complex biological structures and tissues such as the brain, presenting, as far as we know, a new application pathway for OCT in the area of brain science.
Deformed square cavity microlasers, which we propose and demonstrate, produce a highly efficient output from a connected 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. Global chaos ray dynamics and internal mode coupling, combined with a meticulously designed deformation parameter, allow numerical simulations to show efficient resonant light coupling to the multi-mode waveguide's fundamental mode. industrial biotechnology Compared to non-deformed square cavity microlasers, the experimental results demonstrate an approximately six-fold increase in output power, along with a roughly 20% reduction in lasing thresholds. The far-field emission pattern, displaying a high degree of unidirectionality, aligns perfectly with the simulation results, thus showcasing the practicality of deformed square cavity microlasers.
Our findings detail the generation of a 17-cycle mid-infrared pulse exhibiting passive carrier-envelope phase (CEP) stability using the technique of adiabatic difference frequency generation. By employing exclusively material-based compression, a 16-femtosecond pulse, occupying less than two optical cycles, was achieved at a central wavelength of 27 micrometers, with a measured CEP stability that was less than 190 milliradians root mean square. SB-297006 solubility dmso The adiabatic downconversion process's CEP stabilization performance is, to the best of our knowledge, being characterized for the first time.
Within this letter, a simple optical vortex convolution generator is described, using a microlens array for the convolution process and a focusing lens to collect the far-field vortex array, arising 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). Furthermore, the creation of the high-order vortex arrangement is also examined. High spatial frequency vortex arrays are produced by this method, which exhibits a simple structure and high optical power efficiency. This is made possible through the use of devices having lower spatial frequencies, and the method promises significant applications in optical tweezers, optical communication, and optical processing.
The experimental generation of optical frequency combs, in a tellurite microsphere, is reported here for the first time, as far as we know, for tellurite glass microresonators. In the realm of tellurite microresonators, the TeO2-WO3-La2O3-Bi2O3 (TWLB) glass microsphere stands out with its unprecedented Q-factor of 37107. A 61-meter diameter microsphere pumped with 154-nanometer light produces a frequency comb exhibiting seven spectral lines within the normal dispersion spectrum.
A low-refractive-index SiO2 microsphere (or a microcylinder, or a yeast cell), fully immersed, clearly distinguishes a sample with sub-diffraction characteristics under dark-field illumination. The microsphere-assisted microscopy (MAM) resolvable area within the sample is divided into two distinct regions. A virtual image of a region situated beneath the microsphere is initially produced by the microsphere, which then conveys the image to the microscope for recording. The microscope's direct imaging process captures the region surrounding the microsphere, a part of the sample. The resolvable region in the experiment demonstrates a clear correspondence with the simulated enhanced electric field region around the microsphere on the sample surface. The fully immersed microsphere's effect on the sample's surface electric field is shown by our studies to be critical for dark-field MAM imaging, and this will allow researchers to explore new mechanisms for improving MAM resolution.
Phase retrieval plays an irreplaceable role in the operation of a considerable number of coherent imaging systems. Traditional phase retrieval algorithms' capacity to reconstruct fine details is frequently challenged by noise and the restricted exposure. This letter describes an iterative noise-resistant approach to phase retrieval, emphasizing its high fidelity. Within the framework, we explore nonlocal structural sparsity in the complex domain using low-rank regularization, a technique that successfully eliminates artifacts originating from measurement noise. Forward models are instrumental in enabling satisfying detail recovery through the combined optimization of sparsity regularization and data fidelity. By means of developing an adaptive iteration strategy, we augment computational efficiency by dynamically altering the matching frequency. The technique reported here has been validated for both coherent diffraction imaging and Fourier ptychography, achieving a 7dB average increase in peak signal-to-noise ratio (PSNR) relative to conventional alternating projection reconstruction.
Holographic display, a promising three-dimensional (3D) display technology, has been extensively researched. As of this date, real-time holographic displays capable of depicting actual scenes are still largely absent from our daily routines. Further improvement of the speed and quality of information extraction and holographic computing are indispensable. government social media We propose a real-time holographic display method in this paper. Real-time capture of scenes provides parallax images, which are then processed by a CNN to construct the hologram. Parallax images, obtained in real time by a binocular camera, furnish the depth and amplitude information indispensable for generating 3D holograms. The CNN, which can generate 3D holograms from parallax images, is trained on datasets composed of parallax images and high-quality 3D holographic models. The real-time capture of real scenes, for a static, colorful, and speckle-free holographic display, has been empirically confirmed through optical experiments. The proposed technique, utilizing a simple system design and affordable hardware requirements, will overcome the current limitations of real-scene holographic displays, enabling new directions in the application of real-scene holographic 3D display, including holographic live video, and resolving vergence-accommodation conflict (VAC) problems within head-mounted display devices.
In this communication, we present a bridge-connected three-electrode Ge-on-Si APD array, which is designed to be integrated into a complementary metal-oxide-semiconductor (CMOS) system. Beyond the two electrodes already established on the silicon substrate, a third electrode is created for the purpose of germanium integration. Detailed analysis and testing were applied to a single three-electrode APD. The dark current of the device is lessened, and its response is improved, by implementing a positive voltage on the Ge electrode. While the voltage across germanium goes from 0V to 15V, under a constant dark current of 100 nanoamperes, the light responsivity sees a growth from 0.6 A/W to 117 A/W. This is the first reported near-infrared imaging study, to the best of our knowledge, of a three-electrode Ge-on-Si APD array. LiDAR imaging and low-light detection capabilities are demonstrated by experimental results involving the device.
Saturation effects and temporal pulse fragmentation often pose considerable limitations on post-compression methods for ultrafast laser pulses, especially when aiming for substantial compression factors and broad bandwidths. 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. Our method allows for the single-stage post-compression of Yb lasers, enabling them to operate within the few-cycle regime.