The classification of temporal phase unwrapping algorithms usually includes three subgroups: the multi-frequency (hierarchical) method, the multi-wavelength (heterodyne) method, and the number-theoretic approach. The absolute phase's recovery relies crucially on the presence of auxiliary fringe patterns having different spatial frequencies. Many auxiliary patterns are essential for high-accuracy phase unwrapping in the presence of image noise. Subsequently, image noise significantly hinders both the efficiency and the speed of measurement. These three TPU algorithm groupings, consequently, are each based on their own theoretical frameworks and are typically applied in various ways. We present, for the first time according to our findings, a generalized deep learning approach to address TPU tasks for a multitude of TPU algorithm categories. Using deep learning, the proposed framework's experimental results prove its capability to efficiently mitigate noise and substantially improve phase unwrapping reliability, without adding auxiliary patterns for different TPU implementations. We are confident that the proposed methodology holds significant promise for creating robust and dependable phase retrieval approaches.
Considering the substantial use of resonant phenomena in metasurface design to manipulate the behavior of light in terms of bending, slowing, focusing, directing, and controlling its propagation, detailed insight into different resonance types is vital. Numerous studies have examined Fano resonance and its special case, electromagnetically induced transparency (EIT), within the context of coupled resonators, recognizing their high quality factor and strong field confinement. A method based on Floquet modal expansion is presented in this paper for accurately determining the electromagnetic properties of two-dimensional and one-dimensional Fano resonant plasmonic metasurfaces. This method, deviating from the previously documented techniques, demonstrates validity across a broad frequency range for various types of coupled resonators, and its application encompasses practical designs involving the array on one or more dielectric sheets. The flexible and comprehensive formulation allows for the investigation of metal-based and graphene-based plasmonic metasurfaces under normal or oblique illumination. The method demonstrates its accuracy as a tool for creating diverse practical tunable or fixed metasurfaces.
We detail the generation of sub-50 femtosecond pulses from a passively mode-locked YbSrF2 laser, pumped by a spatially single-mode, fiber-coupled laser diode operating at 976 nanometers. The YbSrF2 laser, operating in the continuous-wave regime, produced a peak output power of 704mW at 1048nm, featuring a 64mW threshold and a 772% slope efficiency. Wavelength tuning, continuous and spanning 89nm (from 1006nm to 1095nm), was accomplished by a Lyot filter. By utilizing a semiconductor saturable absorber mirror (SESAM) for the initiation and perpetuation of mode-locked operation, soliton pulses with durations as short as 49 femtoseconds were generated at 1057 nanometers, delivering an average power output of 117 milliwatts with a pulse repetition frequency of 759 megahertz. Scaling up the average output power of the mode-locked YbSrF2 laser to 313mW, for slightly longer pulses of 70 fs at 10494nm, yielded a peak power of 519kW and an exceptional optical efficiency of 347%.
This research paper details the fabrication, design, and experimental verification of a silicon photonic (SiPh) 32×32 Thin-CLOS arrayed waveguide grating router (AWGR) for scalable all-to-all interconnection fabrics using silicon photonics technology. Hydrophobic fumed silica The 3232 Thin-CLOS architecture employs four 16-port silicon nitride AWGRs, which are tightly integrated and interconnected via a multi-layered waveguide routing method. Insertion loss of the manufactured Thin-CLOS is 4 dB, accompanied by adjacent channel crosstalk below -15 dB and non-adjacent channel crosstalk less than -20 dB. Error-free data transmission at 25 Gb/s was verified through the operation of 3232 SiPh Thin-CLOS system experiments.
Microring laser's reliable single-mode operation hinges on the prompt manipulation of its cavity modes. We propose and experimentally validate a plasmonic whispering gallery mode microring laser. This structure exhibits strong coupling between localized plasmonic resonances and whispering gallery modes (WGMs) in the microring cavity, facilitating pure single-mode lasing. Minimal associated pathological lesions A single microring, upon which gold nanoparticles are deposited, is part of the integrated photonics circuits used to create the proposed structure. Furthermore, a numerical simulation provides detailed insight into the complex interplay of gold nanoparticles with WGM modes. Our research findings may prove beneficial to the manufacturing process of microlasers, essential for the advancement of lab-on-a-chip devices and the precise detection of extremely low analyst levels through all-optical methods.
Although visible vortex beams offer various applications, the generation sources are typically substantial or intricate. see more This paper introduces a compact vortex source emitting red, orange, and two wavelengths simultaneously. This PrWaterproof Fluoro-Aluminate Glass fiber laser, with a standard microscope slide functioning as an interferometric output coupler, yields high-quality first-order vortex modes in a compact layout. The demonstration of the broad (5nm) emission bands within orange (610nm), red (637nm), and near-infrared (698nm) regions is further highlighted, with potential green (530nm) and cyan (485nm) emission. Visible vortex applications benefit from the high-quality modes provided by this low-cost, compact, and accessible device.
As a promising platform in the development of THz-wave circuits, parallel plate dielectric waveguides (PPDWs) have seen reports of fundamental devices recently. For the attainment of high-performance PPDW devices, optimal design techniques are vital. The absence of out-of-plane radiation in PPDW makes a mosaic-style optimized design method an apt choice for the PPDW platform. A gradient-based, adjoint variable mosaic design approach is detailed herein for the realization of high-performance THz PPDW devices. The design variables of PPDW devices are efficiently optimized through the application of the gradient method. A mosaic structure in the design region is rendered using the density method, given an appropriate initial solution. Sensitivity analysis, accomplished efficiently through AVM, is integrated into the optimization process. The efficacy of our modular, mosaic-style design is validated by the development of several devices, such as PPDW, T-branch, three-branch mode splitters, and THz bandpass filters. Excluding bandpass filters, the proposed PPDW devices with a mosaic layout showed superior transmission efficiencies during single-frequency and broadband operations. Furthermore, the developed THz bandpass filter successfully achieved the desired flat-top transmission characteristic at the focused frequency band.
The subject of optically trapped particles undergoing rotational motion has drawn substantial attention; however, the variations in angular velocity within a single rotational period present significant challenges. Employing an elliptic Gaussian beam, we propose the optical gradient torque and undertake a novel examination of the instantaneous angular velocities in alignment and fluctuating rotation of trapped, non-spherical particles for the first time. Optical trapping results in particles exhibiting fluctuating rotational behavior. The angular velocity fluctuations, doubling the frequency of the rotation period, provide key information for determining the trapped particle's shape. A new type of wrench, a compact optical wrench, was invented based on its alignment, featuring adjustable torque exceeding that of a similarly powered linearly polarized wrench. Building on these results, precisely modelling the rotational dynamics of optically trapped particles becomes possible, and the wrench described is predicted to be a straightforward and practical instrument for micro-manipulation.
Bound states in the continuum (BICs) in dielectric metasurfaces featuring asymmetric dual rectangular patches within a square lattice unit cell are scrutinized. At normal incidence, the metasurface reveals various BICs, distinguished by exceptionally high quality factors and spectral linewidths that virtually disappear. In the case of fully symmetric four patches, symmetry-protected (SP) BICs manifest, exhibiting field patterns that are antisymmetric and independent of the symmetric incident waves. The SP BICs, when the symmetry of the patch geometry is compromised, are reduced to quasi-BICs, their attributes being identified through Fano resonance. When the symmetry of the upper two patches is broken, while the lower two patches maintain their symmetry, accidental BICs and Friedrich-Wintgen (FW) BICs manifest. Isolated bands experience accidental BICs when either the quadrupole-like or LC-like mode linewidths diminish due to adjustments in the upper vertical gap width. Modifying the lower vertical gap width induces avoided crossings between the dispersion bands of dipole-like and quadrupole-like modes, consequently leading to the appearance of FW BICs. The simultaneous appearance of accidental and FW BICs in the same transmittance or dispersion diagram, along with dipole-like, quadrupole-like, and LC-like modes, is associated with a particular asymmetry ratio.
Employing a TmYVO4 cladding waveguide, meticulously crafted via femtosecond laser direct writing, this investigation showcases tunable 18-m laser operation. Optimizing the pump and resonant conditions within the waveguide laser design, enabled by the excellent optical confinement of the fabricated waveguide, led to efficient thulium laser operation in a compact package. This operation exhibited a maximum slope efficiency of 36%, a minimum lasing threshold of 1768mW, and a tunable output wavelength varying from 1804nm to 1830nm. Studies have meticulously examined the lasing behavior produced by output couplers with differing reflectivity. The waveguide design's exceptional optical confinement and relatively high optical gain empower efficient lasing even without utilizing cavity mirrors, thereby creating innovative opportunities for compact and integrated mid-infrared laser sources.