The results showcase the proposed scheme's exceptional detection accuracy of 95.83%. Furthermore, given that the method emphasizes the temporal manifestation of the received optical signal, supplementary devices and a unique link setup are not demanded.
We propose and demonstrate a polarization-insensitive coherent radio-over-fiber (RoF) link, characterized by improved spectrum efficiency and transmission capacity. The coherent radio-over-fiber (RoF) link utilizes a refined polarization-diversity coherent receiver (PDCR) architecture that streamlines the conventional configuration of two polarization splitters (PBSs), two 90-degree hybrids, and four pairs of balanced photodetectors (PDs) to one PBS, one optical coupler (OC), and two PDs. A novel digital signal processing (DSP) algorithm, unique to our knowledge, is proposed for polarization-insensitive detection and demultiplexing of two spectrally overlapping microwave vector signals at the simplified receiver, eliminating the combined phase noise from the transmitter and local oscillator (LO) lasers. A controlled experiment took place. Over a 25-kilometer single-mode fiber (SMF), the transmission and detection of two separate 16QAM microwave vector signals, each operating at a 3 GHz carrier frequency with a 0.5 GS/s symbol rate, are demonstrated. Due to the superposition of microwave vector signals across the spectrum, both spectral efficiency and data transmission capacity are amplified.
AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs) are advantageous due to their utilization of environmentally sound materials, the possibility of tailoring their emission wavelength, and their propensity for simple miniaturization. Nevertheless, the light extraction effectiveness (LEE) of an AlGaN-based deep-ultraviolet (DUV) light-emitting diode (LED) exhibits a deficiency, thereby impeding its practical applications. A novel plasmonic structure, graphene/aluminum nanoparticle/graphene (Gra/Al NPs/Gra), is designed to significantly enhance the light extraction efficiency (LEE) of a deep ultraviolet (DUV) LED, by a factor of 29, based on the strong resonant coupling of localized surface plasmons (LSPs), as ascertained via photoluminescence (PL) measurements. Through annealing optimization, the dewetting of Al nanoparticles is accomplished more effectively on graphene, promoting uniform distribution and better formation. By means of charge transfer occurring between graphene and aluminum nanoparticles, the near-field coupling of Gra/Al NPs/Gra is amplified. Moreover, a rise in skin depth causes a greater number of excitons to be decoupled from multiple quantum wells (MQWs). An alternative mechanism is outlined, showing that Gra/metal NPs/Gra combinations present a dependable method for enhancing optoelectronic device performance, which could catalyze breakthroughs in the design of high-brightness and high-power LEDs and lasers.
Backscattering, stemming from inconsistencies in conventional polarization beam splitters (PBSs), leads to energy loss and signal distortion. The topological edge states in topological photonic crystals are the key to their backscattering immunity and robustness against disturbance in transmission. A dual-polarization, air-hole fishnet valley photonic crystal exhibiting a common bandgap (CBG) is proposed herein. Through adjustments to the filling ratio of the scatterer, the Dirac points, positioned at the K point and originating from different neighboring bands exhibiting transverse magnetic and transverse electric polarizations, are brought closer. Construction of the CBG involves lifting Dirac cones for dual polarization orientations encompassed by a single frequency range. Further, we design a topological PBS using the proposed CBG, achieving this through changes in the effective refractive index at interfaces that guide polarization-dependent edge modes. The topological polarization beam splitter (TPBS), whose design hinges on tunable edge states, showcases efficient polarization separation and exceptional robustness against sharp bends and defects, as corroborated by simulation data. An approximate footprint of 224,152 square meters for the TPBS allows significant on-chip integration density. Our work's potential is evident in its applicability to photonic integrated circuits and optical communication systems.
We present an all-optical synaptic neuron, implemented using an add-drop microring resonator (ADMRR) with power-adjustable auxiliary light, and demonstrate its functionality. Passive ADMRRs, with their dual neural dynamics, featuring spiking responses and synaptic plasticity, are subject to numerical investigation. Experimental results confirm that injecting two beams of power-adjustable, opposing continuous light into an ADMRR, maintaining a constant sum of their powers, leads to the flexible generation of linearly tunable, single-wavelength neural spikes. This is attributed to nonlinear effects triggered by perturbation pulses. check details Given this, a weighting system, employing a cascading ADMRR architecture, is proposed for achieving real-time operations at various wavelengths. pediatric infection A novel approach for integrated photonic neuromorphic systems, based entirely on optical passive devices, is presented in this work, to the best of our knowledge.
We describe a method to create a dynamically modulated, higher-dimensional synthetic frequency lattice in an optical waveguide system. A two-dimensional frequency lattice results from applying traveling-wave refractive index modulation with the use of two frequencies that do not share a common divisor. The phenomenon of Bloch oscillations (BOs) in the frequency lattice is demonstrated via the introduction of a wave vector mismatch in the modulation scheme. It is only when the wave vector mismatches in orthogonal directions share a commensurable relationship that the BOs are reversible. The topological effect of one-way frequency conversion is demonstrated by the formation of a three-dimensional frequency lattice, which is achieved through an array of waveguides, each modulated by traveling-wave modulation. This study's versatility in exploring higher-dimensional physics within compact optical systems makes it potentially valuable for applications in optical frequency manipulations.
Employing modal phase matching (e+ee), this work demonstrates a highly efficient and tunable on-chip sum-frequency generation (SFG) device fabricated on a lithium niobate thin-film platform. The on-chip SFG solution, leveraging the superior nonlinear coefficient d33 over d31, provides both high efficiency and the absence of poling. A 3-millimeter-long waveguide houses an SFG with an on-chip conversion efficiency of roughly 2143 percent per watt, and a full width at half maximum (FWHM) of 44 nanometers. Optical nonreciprocity devices constructed from thin-film lithium niobate, and chip-scale quantum optical information processing, both benefit from this.
We describe a spectrally selective mid-wave infrared bolometric absorber, passively cooled, that is engineered to independently manage infrared absorption and thermal emission, both in space and wavelength. The structure's operation hinges on the antenna-coupled metal-insulator-metal resonance that enhances mid-wave infrared normal incidence photon absorption, alongside a long-wave infrared optical phonon absorption feature carefully positioned near peak room temperature thermal emission. Grazing-angle-restricted long-wave infrared thermal emission, arising from phonon-mediated resonant absorption, leaves the mid-wave infrared absorption untouched. Independent absorption and emission processes, controlled separately, reveal a detachment of photon detection from radiative cooling. This finding leads to a novel design concept for ultra-thin, passively cooled mid-wave infrared bolometers.
To optimize the traditional Brillouin optical time-domain analysis (BOTDA) system, reducing complexity and improving signal-to-noise ratio (SNR), we propose a frequency-agile scheme that allows for the simultaneous measurement of Brillouin gain and loss spectra. Employing modulation, the pump wave is converted into a double-sideband frequency-agile pump pulse train (DSFA-PPT), with the continuous probe wave having its frequency raised by a constant value. Pump pulses, arising from the -1st-order sideband of DSFA-PPT frequency scanning, and the +1st-order sideband, respectively, engage in stimulated Brillouin scattering with the continuous probe wave. Therefore, a single frequency-agile cycle concurrently produces the Brillouin loss and gain spectra. A 20-ns pump pulse leads to a 365-dB improvement in the signal-to-noise ratio of a synthetic Brillouin spectrum, which distinguishes their characteristics. This work has reduced the complexity of the experimental device, and an optical filter is no longer necessary. The experiment involved the collection of data from static and dynamic measurements.
Terahertz (THz) radiation from an air-based femtosecond filament under a static electric field exhibits an on-axis pattern and a comparatively low frequency spectrum, in contrast to the radiation profiles of single-color and two-color schemes that are not biased. A 15-kV/cm-biased filament in air, illuminated by a 740-nm, 18-mJ, 90-fs pulse, generates measurable THz emissions. The angular distribution of the THz emission demonstrates a shift from a flat-top on-axis pattern (0.5-1 THz) to a marked ring-shaped pattern at 10 THz.
To achieve long-range, high-spatial-resolution distributed measurements, a hybrid aperiodic-coded Brillouin optical correlation domain analysis (HA-coded BOCDA) fiber sensor is introduced. silent HBV infection High-speed phase modulation in BOCDA is observed to create a specific mode of energy transformation. Exploiting this mode allows suppression of all detrimental effects stemming from pulse coding-induced cascaded stimulated Brillouin scattering (SBS), thereby maximizing the potential of HA-coding to enhance BOCDA performance. With a simplified system and a boosted measurement rate, a 7265-kilometer sensing range and a 5-centimeter spatial resolution have been realized, contributing to a temperature/strain measurement accuracy of 2/40.