In light of the benefits of confined-doped fiber, near-rectangular spectral injection, and the 915 nm pump method, a 1007 W signal laser with a linewidth of 128 GHz is generated. This result, to our knowledge, represents the first demonstration surpassing the kilowatt level for all-fiber lasers with GHz-level linewidths. This may offer a valuable reference for simultaneously controlling spectral linewidth, suppressing stimulated Brillouin scattering, and managing thermal issues in high-power, narrow-linewidth fiber lasers.

A high-performance vector torsion sensor, designed using an in-fiber Mach-Zehnder interferometer (MZI), is proposed. The sensor includes a straight waveguide, which is inscribed within the core-cladding boundary of the standard single-mode fiber (SMF) by a single femtosecond laser inscription step. A one-minute fabrication process yields a 5-millimeter in-fiber MZI. Due to its asymmetric structure, the device exhibits a strong polarization dependence, as indicated by a pronounced polarization-dependent dip in the transmission spectrum. The twisting of the fiber alters the polarization state of the incoming light to the in-fiber MZI, thereby allowing torsion sensing through the analysis of the polarization-dependent dip. Torsion demodulation is facilitated by the dip's wavelength and intensity variations, and appropriate polarization of the incident light allows for vector torsion sensing. Torsion sensitivity, measured through the use of intensity modulation, demonstrated a peak value of 576396 dB/(rad/mm). There's a lack of significant correlation between dip intensity, strain, and temperature. In addition, the fiber-integrated MZI structure safeguards the fiber's coating, thus preserving the overall robustness of the fiber.

A novel method for protecting the privacy and security of 3D point cloud classification, built upon an optical chaotic encryption scheme, is presented and implemented herein for the first time, acknowledging the significant challenges in this area. Eganelisib purchase MC-SPVCSELs (mutually coupled spin-polarized vertical-cavity surface-emitting lasers) encountering double optical feedback (DOF) are examined to produce optical chaos for a permutation and diffusion-based encryption scheme for 3D point cloud data. The high chaotic complexity and expansive key space capabilities of MC-SPVCSELs with DOF are evident in the nonlinear dynamics and complexity results. The 40 object categories within the ModelNet40 dataset's test sets were subjected to encryption and decryption via the proposed scheme, and the PointNet++ system meticulously tallied the classification results for the original, encrypted, and decrypted 3D point clouds in each of these 40 categories. Curiously, the accuracy scores of the encrypted point cloud's classes are nearly all zero percent, aside from the exceptional plant class, which has an astonishing one million percent accuracy. This confirms that the encrypted point cloud is not classifiable or identifiable. In terms of accuracy, the decrypted classes' performance is virtually equivalent to that of the original classes. The outcome of the classification process, therefore, reinforces the practical workability and notable effectiveness of the proposed privacy protection methodology. Furthermore, the encryption and decryption processes reveal that the encrypted point cloud images lack clarity and are indecipherable, whereas the decrypted point cloud images precisely match the original ones. This paper's security analysis is enhanced by the examination of the geometric structures presented within 3D point cloud data. The privacy protection scheme, when subjected to thorough security analyses, consistently shows high security and excellent privacy preservation for the 3D point cloud classification process.

The strained graphene-substrate system is predicted to exhibit the quantized photonic spin Hall effect (PSHE) under the influence of a sub-Tesla external magnetic field, significantly less potent than the magnetic field required in traditional graphene-substrate setups. In the PSHE, a distinctive difference in quantized behaviors is found between in-plane and transverse spin-dependent splittings, closely tied to reflection coefficients. The quantization of photo-excited states (PSHE) in graphene with a conventional substrate structure originates from real Landau level splitting, but in a strained graphene-substrate system, the quantized PSHE results from the splitting of pseudo-Landau levels due to pseudo-magnetic fields. The process is further refined by the lifting of valley degeneracy in the n=0 pseudo-Landau levels, which is triggered by the presence of a sub-Tesla external magnetic field. Modifications to the Fermi energy correspondingly impact the quantized nature of the system's pseudo-Brewster angles. The quantized peak values of both the sub-Tesla external magnetic field and the PSHE appear prominently near these angles. The giant quantized PSHE is foreseen to enable direct optical measurements of quantized conductivities and pseudo-Landau levels in the monolayer strained graphene.

Optical communication, environmental monitoring, and intelligent recognition systems have all benefited from the significant interest in polarization-sensitive narrowband photodetection in the near-infrared (NIR) spectrum. The current state of narrowband spectroscopy, however, heavily relies on extra filters or bulk spectrometers, a practice inconsistent with the ambition of achieving on-chip integration miniaturization. Topological phenomena, including the optical Tamm state (OTS), have opened up new pathways for the development of functional photodetectors. We, to the best of our knowledge, are the first to experimentally construct a device based on the 2D material, graphene. Infrared photodetection, sensitive to polarization and narrowband, is shown in OTS-coupled graphene devices, with the utilization of the finite-difference time-domain (FDTD) method for their design. The narrowband response of the devices at NIR wavelengths is a result of the tunable Tamm state's enabling capabilities. The observed full width at half maximum (FWHM) of the response peak stands at 100nm, but potentially increasing the periods of the dielectric distributed Bragg reflector (DBR) could lead to a remarkable improvement, resulting in an ultra-narrow FWHM of 10nm. At 1550nm, the device exhibits a responsivity of 187 milliamperes per watt and a response time of 290 seconds. Eganelisib purchase Furthermore, the integration of gold metasurfaces yields prominent anisotropic features and high dichroic ratios of 46 at 1300nm and 25 at 1500nm.

An experimental demonstration and proposal of a high-speed gas detection system utilizing non-dispersive frequency comb spectroscopy (ND-FCS) is detailed. Its capacity for measuring multiple gases is empirically examined by deploying the time-division-multiplexing (TDM) method for selecting specific wavelengths generated by the fiber laser's optical frequency comb (OFC). A dual-channel optical fiber sensing technique is developed, using a multi-pass gas cell (MPGC) as the sensing element and a reference path with a calibrated signal for monitoring the repetition frequency drift of the OFC. Real-time lock-in compensation and system stabilization are achieved using this configuration. Stability evaluation over the long term, and dynamic monitoring at the same time, are carried out, with ammonia (NH3), carbon monoxide (CO), and carbon dioxide (CO2) as the target gases. The detection of fast CO2 in human breath is also carried out. Eganelisib purchase At an integration time of ten milliseconds, the experimental results demonstrated detection limits of 0.00048%, 0.01869%, and 0.00467% for the three distinct species respectively. A millisecond dynamic response can be coupled with a minimum detectable absorbance (MDA) as low as 2810-4. Our ND-FCS design showcases exceptional gas sensing attributes—high sensitivity, rapid response, and substantial long-term stability. In atmospheric monitoring, it exhibits a promising capacity for tracking multiple components within gases.

Transparent Conducting Oxides (TCOs) display an impressive, super-fast intensity dependence in their refractive index within the Epsilon-Near-Zero (ENZ) range, a variation directly correlated to the materials' properties and measurement conditions. In order to improve the nonlinear response of ENZ TCOs, extensive nonlinear optical measurements are typically undertaken. The material's linear optical response analysis, detailed in this work, showcases a strategy to diminish the substantial experimental efforts needed. This analysis incorporates thickness-dependent material parameters' influence on absorption and field intensity enhancement within diverse measurement setups, thus calculating the necessary incidence angle for maximum nonlinear response in a given TCO film. Nonlinear transmittance measurements, dependent on both angle and intensity, were performed on Indium-Zirconium Oxide (IZrO) thin films with differing thicknesses, demonstrating a satisfactory correlation between empirical findings and theoretical calculations. The film thickness and angle of excitation incidence can be simultaneously optimized to bolster the nonlinear optical response, permitting the flexible development of high nonlinearity optical devices based on transparent conductive oxides, as indicated by our outcomes.

Determining extremely low reflection coefficients at anti-reflective coated surfaces has become paramount in crafting precision instruments, particularly the enormous interferometers used in gravitational wave detection. This paper details a method leveraging low coherence interferometry and balanced detection. This method allows the determination of the spectral dependence of the reflection coefficient's amplitude and phase, achieving a sensitivity of roughly 0.1 ppm and a spectral resolution of 0.2 nm, while simultaneously eliminating any interference stemming from potentially present uncoated interfaces. This method's data processing is structured in a manner analogous to Fourier transform spectrometry's approach. Formulas governing the accuracy and signal-to-noise ratio of this methodology having been established, we now present results that fully validate its successful operation across diverse experimental scenarios.