A 15-meter water tank is instrumental in this paper's design of a UOWC system, employing multilevel polarization shift keying (PolSK) modulation. System performance is then investigated across various transmitted optical powers and temperature gradient-induced turbulence scenarios. The experimental data validates PolSK's effectiveness in countering turbulence, showcasing a superior bit error rate compared to conventional intensity-based modulation methods that falter in achieving an optimal decision threshold under turbulent conditions.
An adaptive fiber Bragg grating stretcher (FBG) in conjunction with a Lyot filter is used to produce bandwidth-limited 10 J pulses of 92 femtoseconds pulse duration. To optimize group delay, a temperature-controlled FBG is employed, whereas the Lyot filter counteracts gain narrowing effects in the amplifier cascade. Hollow-core fiber (HCF) soliton compression unlocks access to the pulse regime of a few cycles. The generation of intricate pulse shapes is made possible by adaptive control strategies.
Many optical systems with symmetrical designs have, in the last decade, showcased the presence of bound states in the continuum (BICs). Within this analysis, we investigate a scenario where anisotropic birefringent material is embedded asymmetrically within a one-dimensional photonic crystal structure. The emergence of this new form allows for the creation of symmetry-protected BICs (SP-BICs) and Friedrich-Wintgen BICs (FW-BICs) through the adjustable tilt of the anisotropy axis. By varying the system's parameters, particularly the incident angle, one can observe these BICs manifested as high-Q resonances. This implies that the structure can exhibit BICs even without the requirement of Brewster's angle alignment. Manufacturing our findings presents minimal difficulty; consequently, active regulation may be possible.
As an essential part of photonic integrated chips, the integrated optical isolator is indispensable. Unfortunately, the performance of on-chip isolators utilizing the magneto-optic (MO) effect has been constrained by the need for magnetization in permanent magnets or metal microstrips integrated with MO materials. This paper details the design of an MZI optical isolator integrated onto a silicon-on-insulator (SOI) chip, dispensing with any external magnetic field requirements. To achieve the necessary saturated magnetic fields for the nonreciprocal effect, a multi-loop graphene microstrip serves as an integrated electromagnet above the waveguide, rather than the standard metal microstrip. The optical transmission can be dynamically tuned afterwards by changing the strength of the currents applied to the graphene microstrip. Compared with gold microstrip, there is a 708% decrease in power consumption and a 695% decrease in temperature variation, with the isolation ratio held at 2944dB and the insertion loss at 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. A series of compact, wavelength-sized devices are designed using topology optimization, focusing on understanding how geometrical optimizations impact processes sensitive to differing field dependencies throughout the device volume, quantified by various figures of merit. Field distributions that vary considerably result in the optimization of distinct processes; consequently, the ideal device geometry is strongly linked to the intended process, showcasing more than an order of magnitude difference in performance between optimized devices. A universal field confinement measure proves inadequate for evaluating device performance, underscoring the necessity of tailoring design metrics to optimize photonic component functionality.
Quantum technologies, including quantum networking, quantum sensing, and computation, rely fundamentally on quantum light sources. To develop these technologies, scalable platforms are necessary, and the innovative discovery of quantum light sources in silicon holds great promise for achieving scalable solutions. To establish color centers within silicon, carbon implantation is frequently employed, which is then followed by rapid thermal annealing. Importantly, the dependence of critical optical characteristics, inhomogeneous broadening, density, and signal-to-background ratio, on the implantation process is poorly elucidated. The research delves into the interplay between rapid thermal annealing and the formation rate of single-color centers in silicon. The relationship between annealing time and the values of density and inhomogeneous broadening is substantial. The observed strain fluctuations are a consequence of nanoscale thermal processes focused on singular points and their effects on the local strain. The theoretical modeling, bolstered by first-principles calculations, provides a sound explanation for our experimental observation. The results highlight annealing as the current key impediment to producing color centers in silicon on a large scale.
This article delves into the optimization of cell temperature for optimal performance of the spin-exchange relaxation-free (SERF) co-magnetometer, integrating both theoretical and practical investigation. Based on the steady-state solution of the Bloch equations, this study develops a model for the steady-state response of the K-Rb-21Ne SERF co-magnetometer output, incorporating cell temperature. A method for determining the ideal cell temperature operating point, incorporating pump laser intensity, is presented in conjunction with the model. The co-magnetometer's scale factor is obtained experimentally as a function of pump laser intensity and cell temperature, coupled with a simultaneous assessment of its long-term stability across various cell temperatures at the corresponding pump laser intensities. The study's results highlight a decrease in the co-magnetometer's bias instability, specifically from 0.0311 degrees per hour to 0.0169 degrees per hour, achieved by optimizing the cell's operational temperature. This outcome affirms the accuracy of the theoretical calculation and the suggested method.
The transformative potential of magnons for the next generation of information technology and quantum computing is undeniable. ONO-AE3-208 The coherent state of magnons, produced by their Bose-Einstein condensation (mBEC), is profoundly significant. mBEC typically originates in the region experiencing magnon excitation. By means of optical procedures, the persistent existence of mBEC, at considerable distances from the magnon excitation region, is demonstrated for the first time. The mBEC phase's uniformity is also apparent. Yttrium iron garnet films, magnetized perpendicular to the plane of the film, were used for experiments conducted at room temperature. ONO-AE3-208 The approach detailed in this article is instrumental in the development of coherent magnonics and quantum logic devices.
A key application of vibrational spectroscopy is in the determination of chemical specifications. 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. Through the numerical analysis of time-resolved surface-sensitive spectroscopy (SFG and DFG) data, featuring a frequency marker in the triggering infrared pulse, the origin of frequency ambiguity was unequivocally attributed to dispersion within the initiating visible pulse, and not to surface structural or dynamical shifts. ONO-AE3-208 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.
A systematic investigation is undertaken into the resonant radiation emitted by localized soliton-like wave-packets within the cascading second-harmonic generation regime. A general mechanism for resonant radiation amplification is presented, dispensing with the need for higher-order dispersion, principally driven by the second-harmonic component, with concomitant emission at the fundamental frequency through parametric down-conversion. Different localized waves, including bright solitons (fundamental and second-order), Akhmediev breathers, and dark solitons, demonstrate the widespread presence of such a mechanism. A simple phase-matching condition is presented to explain the frequencies radiated from these solitons, showing good agreement with numerical simulations under changes in material parameters (including phase mismatch and dispersion ratio). The results offer a clear comprehension of the soliton radiation mechanism operative in quadratic nonlinear media.
A contrasting configuration, featuring one biased and one unbiased VCSEL, situated opposite one another, signifies a potential advancement over the conventional SESAM mode-locked VECSEL approach in generating mode-locked pulses. Numerical analysis of a theoretical model using time-delay differential rate equations shows that the proposed dual-laser configuration operates as a typical gain-absorber system. Current and laser facet reflectivities define a parameter space that showcases general trends in the nonlinear dynamics and pulsed solutions.
We introduce a reconfigurable ultra-broadband mode converter, featuring a two-mode fiber coupled with a pressure-loaded phase-shifted long-period alloyed waveguide grating. Long-period alloyed waveguide gratings (LPAWGs), made from SU-8, chromium, and titanium, are developed and constructed using photo-lithography and electron beam evaporation. The device's reconfigurable mode conversion between LP01 and LP11 modes in the TMF relies on applying or releasing pressure on the LPAWG, making it relatively immune to polarization-related variations. A mode conversion efficiency exceeding 10 dB is attainable within a spectral range of approximately 105 nanometers, encompassing wavelengths from 15019 nanometers to 16067 nanometers. The device's application extends to large bandwidth mode division multiplexing (MDM) transmission and optical fiber sensing systems, leveraging few-mode fibers.