Within this paper, a UOWC system is developed using a 15-meter water tank and multilevel polarization shift keying (PolSK) modulation, and its performance is evaluated under conditions of varying transmitted optical powers and temperature gradient-induced turbulence. The feasibility of PolSK in alleviating turbulence's effects is substantiated by experimental data, showing a remarkable improvement in bit error rate compared to traditional intensity-based modulation methods consistently facing difficulties in establishing an optimal decision threshold within a turbulent communication channel.
With an adaptive fiber Bragg grating stretcher (FBG) and a Lyot filter system, we obtain bandwidth-constrained 10 J pulses having a 92 fs pulse width. To optimize group delay, a temperature-controlled FBG is employed, whereas the Lyot filter counteracts gain narrowing effects in the amplifier cascade. Utilizing soliton compression within a hollow-core fiber (HCF), one gains access to the few-cycle pulse regime. Adaptive control facilitates the creation of complex pulse patterns.
The past decade has witnessed the widespread observation of bound states in the continuum (BICs) within symmetrical geometries in the optical context. This paper examines a case where the structure is asymmetrically designed, embedding anisotropic birefringent material within a one-dimensional photonic crystal. The generation of symmetry-protected BICs (SP-BICs) and Friedrich-Wintgen BICs (FW-BICs) is enabled by this novel shape, which allows for the tuning of anisotropy axis tilt. High-Q resonances characterizing these BICs can be observed by manipulating system parameters, specifically the incident angle. Therefore, the structure displays BICs even when not at Brewster's angle. Active regulation may be facilitated by our findings, which are simple to manufacture.
Photonic integrated chips rely crucially on the integrated optical isolator as a fundamental component. The performance of on-chip magneto-optic (MO) effect-based isolators has been impeded by the magnetization demands of permanent magnets or metallic microstrips used in conjunction with MO materials. A novel MZI optical isolator on silicon-on-insulator (SOI) is introduced, achieving isolation without the need for external magnetic fields. For the nonreciprocal effect, the saturated magnetic fields are produced by a multi-loop graphene microstrip that acts as an integrated electromagnet, positioned above the waveguide, as opposed to the typical metal microstrip. Following this, the optical transmission's characteristics can be adjusted by altering the strength of currents running through the graphene microstrip. Gold microstrip is contrasted with a 708% reduction in power consumption and a 695% decrease in temperature fluctuation, all while maintaining an isolation ratio of 2944dB and an insertion loss of 299dB at 1550 nm.
Significant fluctuations in the rates of optical processes, exemplified by two-photon absorption and spontaneous photon emission, are directly correlated to the environmental conditions, with substantial differences observed in varied settings. By applying topology optimization, we create a range of compact devices at the wavelength scale, exploring the relationship between optimized geometries and the diverse field dependencies present within their volume, as represented by differing figures of merit. Maximizing distinct processes requires significantly diverse field distributions. This directly leads to the conclusion that the optimum device geometry is heavily influenced by the targeted process, producing more than an order of magnitude difference in performance among the optimized designs. Device performance evaluation demonstrates that a universally applicable field confinement metric is useless, thus underscoring the importance of focusing on specific metrics during the design of photonic components.
Quantum technologies, particularly quantum networking, quantum sensing, and quantum computation, find their foundation in quantum light sources. These technologies' advancement demands scalable platforms; the recent discovery of quantum light sources in silicon is a significant and promising indication of scalability potential. Rapid thermal annealing, following carbon implantation, is the prevalent method for generating color centers in silicon. The implantation steps' effect on vital optical parameters, including inhomogeneous broadening, density, and signal-to-background ratio, is poorly understood. Rapid thermal annealing's contribution to the formation kinetics of silicon's single-color centers is investigated. The observed density and inhomogeneous broadening exhibit a strong dependence on the annealing duration. We posit that local strain fluctuations originate from nanoscale thermal processes centered around individual points. The theoretical modeling, bolstered by first-principles calculations, provides a sound explanation for our experimental observation. Currently, the annealing stage acts as the primary limitation in the large-scale fabrication of color centers in silicon, as the results indicate.
We explore, through theoretical and experimental approaches, the cell temperature optimization strategy for the operation of the spin-exchange relaxation-free (SERF) co-magnetometer. The steady-state output of the K-Rb-21Ne SERF co-magnetometer, which depends on cell temperature, is modeled in this paper by using the steady-state Bloch equation solution. A technique for identifying the optimal cell temperature working point, considering pump laser intensity, is developed using the model. Measurements reveal the co-magnetometer's scale factor under different pump laser intensities and cell temperatures, subsequently followed by the characterization of its long-term stability at differing cell temperatures, paired with their corresponding pump laser intensities. The results empirically demonstrate that the optimal operating cell temperature successfully reduced the co-magnetometer's bias instability from 0.0311 degrees per hour to 0.0169 degrees per hour, thereby verifying the theoretical derivation and proposed methodology.
Quantum computing and next-generation information technology are poised to benefit significantly from the immense potential of magnons. TNO155 molecular weight Of particular note is the coherent state of magnons, which emerges from their Bose-Einstein condensation (mBEC). The region of magnon excitation frequently serves as the site for mBEC formation. We optically demonstrate, for the first time, the persistent presence of mBEC at considerable distances from the magnon excitation source. The mBEC phase's uniformity is also apparent. At room temperature, experiments were conducted on yttrium iron garnet films magnetized perpendicular to the film surface. TNO155 molecular weight We leverage the method described in this article for the purpose of developing coherent magnonics and quantum logic devices.
Vibrational spectroscopy is a vital method for characterizing chemical specification. Delay-dependent discrepancies are observed in the spectral band frequencies of sum frequency generation (SFG) and difference frequency generation (DFG) spectra, which relate to the same molecular vibration. The frequency ambiguity observed in time-resolved SFG and DFG spectra, numerically analyzed using a frequency marker in the incident IR pulse, was attributed solely to the dispersion in the incident visible pulse, not to surface structural or dynamic fluctuations. TNO155 molecular weight The outcomes of our study provide a valuable methodology for correcting vibrational frequency deviations, resulting in enhanced accuracy in the assignments of SFG and DFG spectral data.
Localized, soliton-like wave packets exhibiting resonant radiation due to second-harmonic generation in the cascading regime are investigated systematically. A generalized approach to resonant radiation growth is presented, independent of higher-order dispersion, significantly influenced by the second-harmonic component, while simultaneously radiating at the fundamental frequency via parametric down-conversion. The pervasiveness of this mechanism is evident through the examination of various localized waves, for example, bright solitons (both fundamental and second-order), Akhmediev breathers, and dark solitons. A simple phase-matching condition is formulated for frequencies radiated around these solitons, demonstrating excellent agreement with numerical simulations that investigate the modifications in material parameters (e.g., phase mismatch, dispersion ratios). The results expose the mechanism of soliton radiation in quadratic nonlinear media in a direct and unambiguous manner.
A promising configuration for mode-locked pulse generation involves two VCSELs, one biased and the other unbiased, positioned opposite each other, in contrast to the traditional SESAM mode-locked VECSEL. Employing time-delay differential rate equations, a theoretical model is formulated, and numerical results confirm the dual-laser configuration's operation as a conventional gain-absorber system. Laser facet reflectivities and current values are used to characterize the parameter space that illustrates general trends in observed nonlinear dynamics and pulsed solutions.
Presented is a reconfigurable ultra-broadband mode converter, constructed from a two-mode fiber and a pressure-loaded phase-shifted long-period alloyed waveguide grating. Long-period alloyed waveguide gratings (LPAWGs) are fashioned from SU-8, chromium, and titanium, utilizing photolithography and electron beam evaporation techniques in our design and fabrication process. The LPAWG's pressure-dependent application or release on the TMF enables the device to change between LP01 and LP11 modes, showcasing its insensitivity to polarization. Achieving a mode conversion efficiency greater than 10 decibels is feasible with an operational wavelength range spanning from 15019 nanometers to 16067 nanometers, a range encompassing roughly 105 nanometers. The proposed device's further use case includes large bandwidth mode division multiplexing (MDM) transmission and optical fiber sensing systems built around few-mode fibers.