The microsphere's focusing action, coupled with surface plasmon excitation, generates enhanced local electric field (E-field) evanescent illumination on a target object. An amplified local electric field functions as a near-field excitation source, augmenting the scattering of the target object, ultimately resulting in improved imaging resolution.

The substantial retardation demanded by terahertz phase shifters in liquid crystal (LC) devices invariably necessitates thick cell gaps, which in turn noticeably slow down the liquid crystal response. To achieve a superior response, we virtually present a novel method for liquid crystal (LC) switching between in-plane and out-of-plane configurations, enabling reversible transitions among three orthogonal orientations, consequently expanding 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. selleck chemicals llc An applied voltage initiates an electric field, which compels each transition between the three clear orientation states, enabling a rapid response.

Our investigation into single longitudinal mode (SLM) 1240nm diamond Raman lasers encompasses the suppression of secondary modes. A three-mirror V-shaped standing-wave cavity with an intracavity LBO crystal for suppressing secondary modes enabled the production of stable SLM output. This output achieved a peak power of 117 watts and a slope efficiency of 349 percent. Quantifying the level of coupling essential to suppress secondary modes, including those generated by stimulated Brillouin scattering (SBS), is performed. The presence of SBS-generated modes in the beam profile frequently correlates with higher-order spatial modes, and the use of an intracavity aperture is a method to diminish these overlapping modes. selleck chemicals llc Employing numerical computations, it is shown that the probability of occurrence for higher-order spatial modes is higher in an apertureless V-cavity relative to two-mirror cavities, attributable to its distinct longitudinal mode architecture.

A novel driving scheme, to our knowledge, is presented to suppress stimulated Brillouin scattering (SBS) within master oscillator power amplification (MOPA) systems, based on the application of an external high-order phase modulation. Employing linear chirp seed sources, the SBS gain spectrum is uniformly widened, demonstrating a high SBS threshold, motivating the creation of a chirp-like signal, achieved through further signal processing and editing from a piecewise parabolic structure. Unlike the piecewise parabolic signal, the chirp-like signal's linear chirp characteristics are analogous, yielding reduced power requirements and sampling rates, contributing to more effective spectral spreading. The SBS threshold model is theoretically built from the mathematical framework of the three-wave coupling equation. A comparison of the chirp-signal-modulated spectrum with flat-top and Gaussian spectra, in terms of SBS threshold and normalized bandwidth distribution, reveals a significant enhancement. selleck chemicals llc The experimental validation of the design involves the use of a watt-level MOPA amplifier. Modulation of the seed source by a chirp-like signal results in a 35% and 18% improvement in the SBS threshold, at a 3dB bandwidth of 10GHz, compared to flat-top and Gaussian spectra, respectively; and the normalized threshold is the maximum among these options. 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.

To the best of our knowledge, we have demonstrated the first acoustic impedance sensing with sensitivity beyond 3 MHz using forward Brillouin scattering (FBS) induced by radial acoustic modes in a highly nonlinear fiber (HNLF). Radial (R0,m) and torsional-radial (TR2,m) acoustic modes in HNLFs, enabled by efficient acousto-optical coupling, exhibit elevated gain coefficients and scattering efficiencies relative to those in standard single-mode fibers (SSMFs). The enhanced signal-to-noise ratio (SNR) achieved by this method leads to greater measurement precision. Implementing R020 mode in the HNLF setup led to a higher sensitivity of 383 MHz/[kg/(smm2)]. This is noticeably better than the 270 MHz/[kg/(smm2)] sensitivity achieved using the R09 mode in the SSMF, which had a near-maximum gain coefficient. Within the HNLF, employing TR25 mode, sensitivity was found to be 0.24 MHz/[kg/(smm2)], a figure 15 times larger than when using the equivalent mode in SSMF. Improved sensitivity is instrumental in increasing the accuracy of external environment detection using FBS-based sensors.

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 paper introduces an all-fiber low-modal-crosstalk orthogonal combining reception technique for degenerate linearly-polarized (LP) modes. It involves demultiplexing signals in both degenerate modes into the LP01 mode of single-mode fibers, followed by 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. By experiment, a stable real-time transmission of 4-mode 410 Gb/s MDM-wavelength division multiplexing (WDM) was demonstrated for 20 km of few-mode fiber. To support more modes, the proposed scheme is scalable, thus paving the way for the practical implementation of IM/DD MDM transmission applications.

Our analysis concerns a Kerr-lens mode-locked laser based on an Yb3+-doped disordered calcium lithium niobium gallium garnet (YbCLNGG) crystal, and we present our findings here. Using a spatially single-mode Yb fiber laser at 976nm for pumping, the YbCLNGG laser generates soliton pulses as short as 31 femtoseconds at 10568nm, delivering an average output power of 66 milliwatts and a pulse repetition rate of 776 megahertz via soft-aperture Kerr-lens mode-locking. 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%.

Advances in remote sensing technology have propelled the true-color visualization of hyperspectral LiDAR echo signals into the spotlight, both academically and commercially. Hyperspectral LiDAR's power output constraint compromises the spectral-reflectance information in specific channels of the hyperspectral LiDAR echo signal. Color reconstruction, using the hyperspectral LiDAR echo signal as a basis, is likely to suffer from severe color distortions. Addressing the existing problem, this study develops a spectral missing color correction approach based on an adaptive parameter fitting model. Considering the documented absences within the spectral reflectance bands, the colors generated from incomplete spectral integration are modified to accurately represent the intended target colors. The experimental data clearly shows that the proposed color correction model, when applied to hyperspectral color blocks, produces a smaller color difference than the ground truth, thus enhancing image quality and facilitating the accurate reproduction of the target color.

Within the framework of an open Dicke model, this study analyzes steady-state quantum entanglement and steering, taking into account cavity dissipation and individual atomic decoherence. We find that each atom's coupling to independent dephasing and squeezed environments directly invalidates the prevalent Holstein-Primakoff approximation. By examining the characteristics of quantum phase transitions within decohering environments, we primarily observe that (i) cavity dissipation and individual atomic decoherence enhance entanglement and steering between the cavity field and atomic ensemble in both the normal and superradiant phases; (ii) individual atomic spontaneous emission triggers steering between the cavity field and atomic ensemble, but simultaneous steering in both directions is not possible; (iii) the maximum achievable steering in the normal phase surpasses that of the superradiant phase; (iv) entanglement and steering between the cavity output field and atomic ensemble are significantly stronger than those with the intracavity field, and simultaneous steering in two directions can be achieved even with the same parameters. Individual atomic decoherence processes, in conjunction with the open Dicke model, are examined by our findings, revealing distinctive properties of quantum correlations.

The reduced resolution of polarized images creates obstacles to discerning intricate polarization details, thereby reducing the effectiveness of identifying small targets and weak signals. The polarization super-resolution (SR) technique can be used as a solution to this issue, aimed at deriving a high-resolution polarized image from the given low-resolution one. Polarization super-resolution (SR) presents a far more challenging problem than traditional intensity-mode super-resolution (SR). This is primarily due to the simultaneous need to reconstruct polarization and intensity information, coupled with the inclusion of multiple channels and their intricate interdependencies. This research paper delves into the issue of polarized image degradation and introduces a deep convolutional neural network for polarization super-resolution reconstruction, drawing on two different models of degradation. Effective intensity and polarization information restoration has been confirmed for the network structure, validated by the well-designed loss function, enabling super-resolution with a maximum scaling factor of four.