Surface plasmon excitation, in conjunction with microsphere focusing, results in an object experiencing enhanced local electric field (E-field) evanescent illumination. A strengthened local electric field acts as a near-field source of excitation, enhancing the object's scattering and thereby improving the quality of the imaging resolution.

Liquid crystal (LC) terahertz phase shifters, owing to the need for substantial retardation, frequently employ thick cell gaps, thus compromising the speed of LC response. Virtually demonstrating a novel liquid crystal (LC) switching method for reversible transitions between three orthogonal orientations (in-plane and out-of-plane), we aim to enhance the response and expand the range of continuous phase shifts. LC switching is achieved via two substrates, each featuring two pairs of orthogonal finger electrodes and a single grating electrode for in- and out-of-plane control. BAY 1000394 price Through the application of voltage, an electric field is generated to drive each switching process among the three distinct orientations, allowing for a rapid response.

Within this report, we investigate the suppression of secondary modes in 1240nm single longitudinal mode (SLM) diamond Raman lasers. We achieved stable SLM output within a three-mirror V-shape standing-wave cavity, featuring an intra-cavity LBO crystal for suppressing secondary modes. The output power reached a maximum of 117 W, and the slope efficiency was 349%. We measure the required coupling intensity to subdue secondary modes, including those provoked by stimulated Brillouin scattering (SBS). Analysis indicates that SBS-created modes frequently overlap with higher-order spatial modes in the beam pattern, which can be eliminated with an intracavity aperture. BAY 1000394 price Calculations using numerical methods indicate that the probability of higher-order spatial modes is greater in an apertureless V-cavity than in two-mirror cavities, due to the differing longitudinal mode structures.

We propose, to our knowledge, a novel driving scheme for suppressing the stimulated Brillouin scattering (SBS) effect in master oscillator power amplification (MOPA) systems, employing an externally applied high-order phase modulation. Because linear chirp seed sources yield a uniform broadening of the SBS gain spectrum, exceeding a high SBS threshold, a chirp-like signal was developed from a piecewise parabolic signal, augmenting it with subsequent editing and processing. Compared to a traditional piecewise parabolic signal, the chirp-like signal exhibits similar linear chirp features. This facilitates reductions in driving power and sampling rate, leading to a more effective spectral dispersion. The theoretical structure of the SBS threshold model is built upon the three-wave coupling equation's principles. The chirp-signal-modulated spectrum is compared against flat-top and Gaussian spectra, focusing on SBS threshold and normalized bandwidth distribution, highlighting a noteworthy improvement. BAY 1000394 price Experimental validation of the design is performed on a watt-class MOPA amplifier. The seed source, modulated by a chirp-like signal, demonstrates a 35% enhancement in SBS threshold at a 3dB bandwidth of 10GHz when compared to a flat-top spectrum, and a 18% improvement when compared to a Gaussian spectrum. Its normalized threshold is also the highest. The results of our research show that the ability to suppress stimulated Brillouin scattering (SBS) is not limited to optimizing spectral power; temporal domain engineering also plays a significant role. This discovery presents a fresh perspective on optimizing and improving the SBS threshold of narrow-linewidth fiber lasers.

The first demonstration of acoustic impedance sensing with a sensitivity exceeding 3 MHz has, to the best of our knowledge, been achieved by employing forward Brillouin scattering (FBS) driven by radial acoustic modes in a highly nonlinear fiber (HNLF). The enhanced acousto-optical coupling within HNLFs amplifies the gain coefficients and scattering efficiencies of both radial (R0,m) and torsional-radial (TR2,m) acoustic modes, surpassing those found in standard single-mode fibers (SSMFs). This methodology facilitates higher signal-to-noise ratio (SNR), thereby promoting greater sensitivity in the measurements. R020 mode in HNLF yielded a heightened sensitivity of 383 MHz/[kg/(smm2)] which is superior to the 270 MHz/[kg/(smm2)] sensitivity measured for R09 mode in SSMF, which almost reached the largest gain coefficient. The sensitivity, determined by using the TR25 mode in HNLF, stood at 0.24 MHz/[kg/(smm2)], a value 15 times higher than the sensitivity observed when employing the same mode in SSMF. Enhanced sensitivity will elevate the precision of FBS sensor-based external environment detection.

Optical interconnections, a type of short-reach application, can benefit from the potential of weakly-coupled mode division multiplexing (MDM) techniques. These techniques enable intensity modulation and direct detection (IM/DD) transmission, while simultaneously requiring low-modal-crosstalk mode multiplexers/demultiplexers (MMUX/MDEMUX). Our proposed all-fiber, low-modal-crosstalk orthogonal combining reception scheme for degenerate linearly-polarized (LP) modes involves first demultiplexing signals in both degenerate modes into the LP01 mode of single-mode fibers, then multiplexing them into mutually orthogonal LP01 and LP11 modes of a two-mode fiber for simultaneous detection. Using side-polishing processing, cascaded mode-selective couplers and orthogonal combiners were assembled into 4-LP-mode MMUX/MDEMUX pairs. These fabricated devices achieve exceptionally low modal crosstalk, below -1851 dB, and insertion losses below 381 dB, across all four modes. A 20-km few-mode fiber experiment successfully demonstrated stable real-time 4-mode 410 Gb/s MDM-wavelength division multiplexing (WDM) transmission. Scalable in design, the proposed scheme caters to additional modes, thereby potentially enabling practical IM/DD MDM transmission applications.

This report examines a Kerr-lens mode-locked laser, its core component being an Yb3+-doped disordered calcium lithium niobium gallium garnet (YbCLNGG) crystal. At 976nm, a spatially single-mode Yb fiber laser pumps the YbCLNGG laser, resulting in soliton pulses as short as 31 femtoseconds at 10568nm. This laser, utilizing soft-aperture Kerr-lens mode-locking, delivers an average output power of 66 milliwatts and a pulse repetition rate of 776 megahertz. An absorbed pump power of 0.74 watts resulted in a maximum output power of 203mW from the Kerr-lens mode-locked laser, associated with slightly longer 37 femtosecond pulses. This translates to a peak power of 622kW and an optical efficiency of 203%.

True-color visualization of hyperspectral LiDAR echo signals has become a central focus of research and commercial applications, driven by advancements in remote sensing technology. Spectral-reflectance data is lost in some channels of the hyperspectral LiDAR echo signal due to the emission power limitation of the hyperspectral LiDAR. Color casts are virtually unavoidable when hyperspectral LiDAR echo signals are used for color reconstruction. Addressing the existing problem, this study develops a spectral missing color correction approach based on an adaptive parameter fitting model. Considering the established intervals lacking in spectral reflectance, the colors calculated in the incomplete spectral integration process are calibrated to faithfully reproduce the desired target colors. Employing the proposed color correction model on hyperspectral images of color blocks, the experimental results show a smaller color difference compared to the ground truth, along with superior image quality, enabling precise target color reproduction.

This paper focuses on the study of steady-state quantum entanglement and steering in an open Dicke model, which includes the effects of cavity dissipation and individual atomic decoherence. Indeed, the independent dephasing and squeezed environments coupled to each atom invalidate the frequently used Holstein-Primakoff approximation. Examination of quantum phase transitions within decohering environments demonstrates: (i) In both the normal and superradiant phases, cavity dissipation and individual atomic decoherence enhance the entanglement and steering between the cavity field and the atomic ensemble; (ii) spontaneous emission from individual atoms results in steering between the cavity field and the atomic ensemble, however simultaneous steering in both directions is not generated; (iii) maximum achievable steering in the normal phase is stronger than in the superradiant phase; (iv) the entanglement and steering between the cavity output field and atomic ensemble are substantially stronger than those with the intracavity field, and simultaneous steering in opposing directions is attainable even at the same parameter levels. Quantum correlations in the open Dicke model, influenced by individual atomic decoherence processes, show unique features, as demonstrated by our findings.

Limited resolution in polarized images makes it difficult to extract precise polarization information, impeding the detection of subtle targets and signals. Polarization super-resolution (SR) is a potential strategy for managing this problem, with the objective of creating a high-resolution polarized image from a lower-resolution version. The polarization super-resolution (SR) process stands in stark contrast to traditional intensity-based SR. The added intricacy of polarization SR originates from the parallel reconstruction of intensity and polarization data, while simultaneously acknowledging and incorporating the multiple channels and their complex interconnections. Examining the polarization-induced image degradation, this paper presents a deep convolutional neural network to reconstruct polarization super-resolution images, considering two different degradation models. Validation of the network architecture and loss function reveals their successful harmonization of intensity and polarization information restoration, allowing for super-resolution with a maximum upscaling factor of four.