To achieve simultaneous recovery of a binary mask and the sample's wave field within a lensless masked imaging system, a self-calibrated phase retrieval (SCPR) method is proposed. Our image restoration method, significantly more efficient and adaptable than traditional techniques, achieves superior results without requiring any extra calibration device. A comparative study of experimental results from different samples confirms our method's superior performance.
To attain efficient beam splitting, metagratings possessing zero load impedance are proposed. Previous metagrating implementations, demanding specific capacitive and/or inductive architectures for load impedance matching, are contrasted by the proposed metagrating, which comprises solely microstrip-line structures. A structure of this kind bypasses the limitations associated with implementation, thereby permitting the use of low-cost fabrication techniques in metagratings operating at higher frequencies. To attain the precise design parameters, the detailed theoretical design procedure is presented along with the associated numerical optimizations. In the concluding phase, multiple reflection-based beam-splitting devices, each employing a separate pointing angle, were designed, simulated, and carefully measured in experiments. The 30GHz results showcase outstanding performance, facilitating the development of cost-effective printed circuit board (PCB) metagratings for millimeter-wave and higher frequencies.
Out-of-plane lattice plasmon characteristics exhibit substantial potential for enhancing quality factors, thanks to strong coupling between particles. Still, the precise conditions of oblique incidence obstruct the conduct of experimental observation. This letter, to the best of our knowledge, introduces a novel mechanism for generating OLPs via near-field coupling. Importantly, the deployment of specially designed nanostructural dislocations enables the attainment of the strongest OLP at normal incidence. OLPs' energy flux direction is principally governed by the wave vectors of Rayleigh anomalies. Subsequent investigations demonstrated that the OLP exhibits symmetry-protected bound states within the continuum, thereby resolving the discrepancy observed in prior studies regarding the inability of symmetric structures to excite OLPs at normal incidence. Understanding OLP is enhanced by our work, leading to the benefit of developing flexible functional plasmonic devices.
We demonstrate and confirm a novel approach, as far as we know, for achieving high coupling efficiency (CE) in grating couplers (GCs) integrated onto lithium niobate on insulator photonic platforms. Fortifying the grating on the GC with a high refractive index polysilicon layer is the method used to achieve enhanced CE. Light within the lithium niobate waveguide is drawn upward into the grating region due to the substantial refractive index of the polysilicon layer. check details The vertical optical cavity's formation boosts the waveguide GC's CE. The simulations, utilizing this novel configuration, projected a CE of -140dB. Experimental measurements, however, indicated a substantially different CE of -220dB, with a 3-dB bandwidth of 81nm between 1592nm and 1673nm. The high CE GC is successfully achieved without employing bottom metal reflectors or the requirement for etching the lithium niobate substrate.
A 12-meter laser operation, exceptionally powerful, was achieved within Ho3+-doped, in-house produced single-cladding ZrF4-BaF2-YF3-AlF3 (ZBYA) glass fibers. Biofuel combustion Fibers were produced from ZBYA glass, a composite material made of ZrF4, BaF2, YF3, and AlF3. The 05-mol% Ho3+-doped ZBYA fiber, when pumped by an 1150-nm Raman fiber laser, exhibited a maximum combined laser output power of 67 W from both sides, achieving a slope efficiency of 405%. Lasering at 29 meters, with an output power of 350 milliwatts, was observed and attributed to the Ho³⁺ ⁵I₆ → ⁵I₇ transition. The study also involved examining how variations in rare earth (RE) doping concentration and gain fiber length affected laser performance measurements at the 12-meter and 29-meter distances.
Direct detection transmission with intensity modulation (IM/DD), integrated with mode-group-division multiplexing (MGDM), is a compelling method to increase the capacity of short-reach optical communication. In this letter, a flexible yet basic mode group (MG) filtering technique is presented for MGDM IM/DD transmission. Regardless of the mode basis in the fiber, this scheme ensures low complexity, low power consumption, and superior system performance. A 152-Gb/s raw bit rate was experimentally demonstrated over a 5-km few-mode fiber (FMF) utilizing a multiple-input-multiple-output (MIMO)-free in-phase/quadrature (IM/DD) co-channel simultaneous transmit/receive system. Two orbital angular momentum (OAM) multiplexing channels, each carrying 38-GBaud PAM-4 signals, were employed using the proposed MG filter approach. Employing simple feedforward equalization (FFE), the bit error ratios (BERs) of both MGs remain below the 7% hard-decision forward error correction (HD-FEC) BER threshold at the 3810-3 level. Additionally, the dependability and robustness of such MGDM linkages are critically significant. In this manner, each MG's dynamic BER and signal-to-noise ratio (SNR) are evaluated over 210 minutes, reflecting the diverse circumstances. Under dynamic conditions, the BER values obtained through our proposed strategy consistently remain below 110-3, hence supporting the inherent stability and applicability of the proposed MGDM transmission scheme.
Photonic crystal fibers (PCFs), employing nonlinear effects, are extensively utilized for generating broadband supercontinuum (SC) light sources. This has enabled significant advancements in spectroscopy, metrology, and microscopy applications. The quest to extend the short-wavelength output of SC sources, a longstanding pursuit, has driven intense research efforts for the past two decades. Despite this, the precise manner in which blue and ultraviolet light are generated, especially regarding specific resonance spectral peaks in the short-wavelength domain, is not completely understood. Our findings demonstrate that inter-modal dispersive-wave radiation, which stems from phase matching of pump pulses in the fundamental optical mode to wave packets in higher-order modes (HOMs) propagating within the PCF core, may be a crucial contributor to the generation of resonance spectral components with wavelengths shorter than the pump light's. During the experiment, we noted spectral peaks situated in the blue and ultraviolet portions of the SC spectrum. The central wavelengths of these peaks are modified by adjustments to the PCF core diameter. Bedside teaching – medical education Insights into the SC generation process are gleaned from a comprehensive interpretation of these experimental results, facilitated by the inter-modal phase-matching theory.
Within this letter, we introduce what we believe to be a new method for single-exposure quantitative phase microscopy. This method hinges on phase retrieval techniques, employing the simultaneous acquisition of a band-limited image and its corresponding Fourier image. Acknowledging the intrinsic physical constraints of microscopy systems within the phase retrieval algorithm, we eliminate the reconstruction's inherent ambiguities, achieving rapid iterative convergence. This system's key advantage is its independence from the stringent object support and oversampling demanded by coherent diffraction imaging. Employing our algorithm, both simulations and experiments validate the swift phase retrieval from a single-exposure measurement. Real-time, quantitative biological imaging using presented phase microscopy shows promise.
From the temporal correlations of two optical beams, temporal ghost imaging constructs a temporal representation of a transient object. This representation's resolution is constrained by the response time of the photodetector, reaching a recent peak of 55 picoseconds in experimental settings. To enhance temporal resolution, a spatial ghost image of a temporal object, utilizing the strong temporal-spatial correlations of two optical beams, is recommended. There are established correlations between entangled beams arising from the process of type-I parametric downconversion. Studies have revealed that a sub-picosecond-scale temporal resolution is accessible with a realistic entangled photon source.
Measurements of nonlinear refractive indices (n2) at 1030 nm were performed on a variety of bulk crystals (LiB3O5, KTiOAsO4, MgOLiNbO3, LiGaS2, ZnSe) and liquid crystals (E7, MLC2132) using nonlinear chirped interferometry, achieving sub-picosecond (200 fs) resolution. The reported values are indispensable for defining the key parameters needed for the design of near- to mid-infrared parametric sources and all-optical delay lines.
Meticulously designed bio-integrated optoelectronic and high-end wearable systems require the use of mechanically flexible photonic devices. The precise control of optical signals is accomplished through thermo-optic switches (TOSs). Using a Mach-Zehnder interferometer (MZI) architecture, this paper reports the first demonstration of flexible titanium dioxide (TiO2) transmission optical switches (TOSs) around 1310nm, as we understand it. Each multi-mode interferometer (MMI) within the flexible passive TiO2 22 system demonstrates a -31dB insertion loss. The flexible terms of service (TOS), exhibiting flexibility, achieved a power consumption (P) of 083mW, in contrast to the rigid TOS, where power consumption (P) was reduced by a factor of 18. The device's proposed design demonstrated remarkable mechanical resilience, enduring 100 consecutive bending cycles without any discernible decline in TOS performance. Future emerging applications will benefit from a novel perspective on designing and fabricating flexible TOSs for flexible optoelectronic systems, as evidenced by these results.
A straightforward thin-layer structure, capitalizing on epsilon-near-zero mode field enhancement, is presented to accomplish optical bistability in the near-infrared spectral band. The thin-layer structure's high transmittance, combined with the localized electric field energy within the ultra-thin epsilon-near-zero material, dramatically increases the interaction between input light and the epsilon-near-zero material, creating the ideal conditions for optical bistability in the near-infrared band.