From the synthesis of confined-doped fiber, near-rectangular spectral injection, and a 915 nm pump mechanism, a 1007 W signal laser with a 128 GHz linewidth is produced. We believe this result constitutes the initial demonstration beyond the kilowatt power level for all-fiber lasers featuring GHz-level linewidths. This breakthrough could establish a valuable reference point for controlling spectral linewidth, minimizing stimulated Brillouin scattering, and suppressing thermal management issues in high-power, narrow-linewidth fiber lasers.

For a high-performance vector torsion sensor, we suggest an in-fiber Mach-Zehnder interferometer (MZI) architecture. This architecture comprises a straight waveguide inscribed within the core-cladding boundary of the single-mode fiber (SMF) with a single laser inscription step using a femtosecond laser. Within one minute, the entire fabrication process for the 5-millimeter in-fiber MZI is completed. The asymmetrically structured device displays high polarization dependence, as characterized by the transmission spectrum's strong polarization-dependent dip. Monitoring the polarization-dependent dip in the in-fiber MZI's response to the twisting of the fiber allows for torsion sensing, as the polarization state of the input light changes accordingly. Torsion is demodulated by the wavelength and intensity of the dip's oscillations, and vector torsion sensing is accomplished through the precise polarization control of the incoming light. Intensity modulation yields a torsion sensitivity of 576396 dB per radian per millimeter. There's a lack of significant correlation between dip intensity, strain, and temperature. Subsequently, the MZI implemented directly within the fiber retains the fiber's coating, thus preserving the strength and durability of the complete fiber system.

This paper details a new method for securing 3D point cloud classification using an optical chaotic encryption scheme, implemented for the first time. This approach directly addresses the privacy and security problems associated with this area. EN450 chemical structure Spin-polarized vertical-cavity surface-emitting lasers (MC-SPVCSELs) with mutual coupling, exposed to double optical feedback (DOF), are examined for generating optical chaos used in the encryption of 3D point clouds with permutation and diffusion. MC-SPVCSELs incorporating DOF showcase high chaotic complexity, as quantified by the nonlinear dynamics and complexity results, thus affording a tremendously large key space. The proposed scheme encrypted and decrypted the 40 object categories' test sets within the ModelNet40 dataset, and the PointNet++ documented the classification outcomes for the original, encrypted, and decrypted 3D point clouds for each of these 40 categories. The encrypted point cloud's class accuracies are, curiously, almost all identically zero percent, apart from the plant class, which shows an astonishingly high one million percent accuracy, making it impossible to categorize and identify the point cloud. The decryption classes' accuracy scores are extraordinarily comparable to the accuracy scores of the original classes. In conclusion, the classification findings confirm the tangible feasibility and substantial efficacy of the proposed privacy preservation scheme. The encryption and decryption procedures, in fact, demonstrate the ambiguity and unintelligibility of the encrypted point cloud images, while the decrypted images perfectly replicate the original point cloud data. Furthermore, the security analysis is refined in this paper by considering the geometric characteristics of 3D point clouds. The security analysis of the suggested privacy preservation methodology for 3D point cloud classification consistently shows high security and effective privacy protection.

Within a strained graphene-substrate configuration, the quantized photonic spin Hall effect (PSHE) is predicted to materialize under the impact of a sub-Tesla external magnetic field, a substantially weaker magnetic field than conventionally required for the effect within the graphene-substrate system. Studies on the PSHE reveal that the in-plane and transverse spin-dependent splittings exhibit different quantized behaviors, which are strongly linked to reflection coefficients. The difference in quantized photo-excited states (PSHE) between a conventional graphene substrate and a strained graphene substrate lies in the underlying mechanism. The conventional substrate's PSHE quantization stems from real Landau level splitting, while the strained substrate's PSHE quantization results from pseudo-Landau level splitting, influenced by a pseudo-magnetic field. This effect is also contingent on the lifting of valley degeneracy in the n=0 pseudo-Landau levels, driven by sub-Tesla external magnetic fields. As the Fermi energy evolves, the pseudo-Brewster angles of the system are correspondingly quantized. Near these angles, the sub-Tesla external magnetic field and the PSHE exhibit quantized peak values. Employing the giant quantized PSHE, direct optical measurements of the quantized conductivities and pseudo-Landau levels in monolayer strained graphene are expected.

Near-infrared (NIR) polarization-sensitive narrowband photodetection has garnered considerable attention in optical communication, environmental monitoring, and intelligent recognition systems. Despite its current reliance on extra filters or large spectrometers, narrowband spectroscopy's design is inconsistent with the imperative for on-chip integration miniaturization. Optical Tamm states (OTS), a manifestation of topological phenomena, have recently presented a novel approach to designing functional photodetectors. To the best of our knowledge, we have experimentally implemented the first device of this kind, utilizing a 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 devices' narrowband response at NIR wavelengths is a consequence of the tunable Tamm state. A full width at half maximum (FWHM) of 100nm is observed in the response peak, a possibility for an ultra-narrow FWHM of approximately 10nm exists, contingent upon increasing the periods of the dielectric distributed Bragg reflector (DBR). At a wavelength of 1550nm, the device demonstrates a responsivity of 187mA/W and a response time of 290 seconds. EN450 chemical structure Gold metasurfaces, when integrated, create prominent anisotropic features and achieve high dichroic ratios of 46 at 1300nm and 25 at 1500nm.

Experimental verification and proposition of a rapid gas detection method based on non-dispersive frequency comb spectroscopy (ND-FCS) is given. A time-division-multiplexing (TDM) approach is implemented in the experimental study of its multi-gas measurement capacity, allowing for the targeted wavelength selection of the fiber laser optical frequency comb (OFC). For real-time lock-in compensation and stabilization of an optical fiber cavity (OFC), a dual-channel optical fiber sensing system is implemented. The sensing path includes a multi-pass gas cell (MPGC), while a precisely calibrated reference path is used to track the repetition frequency drift. We conduct long-term stability evaluation and simultaneous dynamic monitoring of the target gases ammonia (NH3), carbon monoxide (CO), and carbon dioxide (CO2). The rapid detection of CO2 in human respiration is also performed. EN450 chemical structure Regarding the detection limits of the three species, the experimental results, obtained at a 10 ms integration time, yielded values of 0.00048%, 0.01869%, and 0.00467%, respectively. A millisecond dynamic response can be coupled with a minimum detectable absorbance (MDA) as low as 2810-4. The ND-FCS displays excellent gas sensing characteristics, including high sensitivity, swift response times, and sustained stability over extended periods. The capacity for monitoring multiple gas types within atmospheric monitoring applications is strongly suggested by this technology.

Epsilon-Near-Zero (ENZ) spectral regions of Transparent Conducting Oxides (TCOs) reveal a substantial and ultra-fast change in refractive index, which is intricately tied to the material's properties and the specific measurement process employed. Consequently, optimizing the nonlinear behavior of ENZ TCOs frequently necessitates a substantial investment in nonlinear optical measurements. Through examination of the material's linear optical response, this study demonstrates the potential for minimizing substantial experimental efforts. Different measurement contexts are accounted for in the analysis of thickness-dependent material parameters on absorption and field intensity enhancement, calculating the optimal incidence angle to achieve maximum nonlinear response in a particular TCO film. Using Indium-Zirconium Oxide (IZrO) thin films with a spectrum of thicknesses, we measured the nonlinear transmittance, contingent on both angle and intensity, and found a strong correlation with the predicted values. The optimization of nonlinear optical response through the simultaneous adjustment of film thickness and excitation angle of incidence permits the flexible design of TCO-based high-nonlinearity optical devices, as indicated by our results.

For the creation of high-precision instruments, such as the enormous interferometers used to detect gravitational waves, accurately measuring very low reflection coefficients of anti-reflective coated interfaces has become critical. 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. The data processing implemented in this method shares characteristics with that utilized in Fourier transform spectrometry. The formulas governing precision and signal-to-noise have been established, and the results presented fully demonstrate the success of this methodology across a spectrum of experimental settings.