This paper investigates the energy-conscious routing methodology for satellite laser communication and develops a satellite degradation model. The model's data informs our proposal of an energy-efficient routing scheme using a genetic algorithm. The proposed method significantly outperforms shortest path routing, increasing satellite lifespan by 300%. Despite minimal performance degradation, the blocking ratio is augmented by 12%, and the service delay is increased by 13 milliseconds.

Metalenses featuring extended depth of field (EDOF) are capable of generating broader image maps, propelling innovations in imaging and microscopy. Forward-designed EDOF metalenses currently face issues like asymmetric point spread functions and non-uniform focal spot distribution, compromising image quality. We present a double-process genetic algorithm (DPGA) solution for the inverse design of EDOF metalenses to address these problems. In employing different mutation operators in consecutive genetic algorithm (GA) runs, the DPGA approach exhibits significant advantages in determining the optimal solution throughout the complete parameter space. This method separately designs 1D and 2D EDOF metalenses operating at 980nm, both achieving a substantial improvement in depth of focus (DOF) compared to conventional focusing. Moreover, a consistently distributed focal spot is successfully maintained, ensuring stable imaging quality throughout the axial dimension. Significant applications of the proposed EDOF metalenses exist in biological microscopy and imaging, and the DPGA approach can be applied to the inverse design of various other nanophotonics devices.

Military and civil applications will leverage multispectral stealth technology, incorporating the terahertz (THz) band, to an amplified degree. selleck Based on the modular design concept, two types of adaptable and transparent metadevices were developed for multispectral stealth capabilities, spanning the visible, infrared, THz, and microwave bands. Three essential functional blocks for achieving IR, THz, and microwave stealth are meticulously designed and produced utilizing flexible and transparent films. Two multispectral stealth metadevices are readily attainable by way of modular assembly, whereby concealed functional blocks or constituent layers are incorporated or eliminated. Metadevice 1 showcases dual-band broadband absorption across THz and microwave frequencies, averaging 85% absorptivity in the 03-12 THz range and exceeding 90% in the 91-251 GHz range, making it suitable for THz-microwave bi-stealth applications. Infrared and microwave bi-stealth are achieved by Metadevice 2, which registers absorptivity higher than 90% within the 97-273 GHz frequency range and displays low emissivity, approximately 0.31, within the 8-14 meter span. Optically transparent, the metadevices maintain their exceptional stealth capabilities in curved and conformal environments. By exploring different approaches to designing and fabricating flexible transparent metadevices, our work provides a novel solution for multispectral stealth, particularly for use on nonplanar surfaces.

This research presents a novel surface plasmon-enhanced dark-field microsphere-assisted microscopy method for imaging both low-contrast dielectric objects and metallic ones, a first. Employing an Al patch array as a substrate, we showcase enhanced resolution and contrast when imaging low-contrast dielectric objects in dark-field microscopy (DFM), compared to metal plate and glass slide substrates. On three substrates, 365-nanometer diameter hexagonally arranged SiO nanodots resolve, showing contrast variations between 0.23 and 0.96. Meanwhile, only on the Al patch array substrate are 300-nanometer diameter, hexagonally close-packed polystyrene nanoparticles recognizable. The resolution capability of microscopy can be further enhanced with the use of dark-field microsphere assistance, enabling the differentiation of an Al nanodot array with a 65nm diameter for the nanodots and a 125nm center-to-center separation, a feat presently unachievable through conventional DFM. An object experiences an enhanced local electric field (E-field), due to the combined effects of microsphere focusing and surface plasmon excitation, leading to evanescent illumination. selleck 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.

Thick cell gaps, a necessity for the required retardation in terahertz phase shifter liquid crystal (LC) devices, unfortunately lead to significant delays in LC response times. We virtually demonstrate a novel liquid crystal (LC) switching technique, allowing for reversible transitions between three orthogonal orientations (in-plane and out-of-plane), thereby improving the response and broadening the continuous phase shift range. Employing a pair of substrates, each possessing two pairs of orthogonal finger-type electrodes and one grating-type electrode, allows for the realization of this LC switching mechanism for in- and out-of-plane switching. The application of a voltage produces an electric field that governs the switching procedures among the three different orientations, enabling a swift response.

This report details an investigation of secondary mode suppression within single longitudinal mode (SLM) 1240nm diamond Raman lasers. selleck Within a three-mirror V-shaped standing-wave resonator, featuring an intracavity lithium triborate (LBO) crystal for mitigating secondary modes, we successfully generated a stable SLM output exhibiting a maximum power of 117 watts and a slope efficiency of 349 percent. We assess the degree of coupling required to quell secondary modes, encompassing those originating from stimulated Brillouin scattering (SBS). In beam profiles, SBS-generated modes commonly align with higher-order spatial modes, and the use of an intracavity aperture can effectively eliminate these modes. Numerical calculations confirm a superior probability for higher-order spatial modes within an apertureless V-cavity in comparison to two-mirror cavities, arising from its distinct longitudinal mode pattern.

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. Seed sources incorporating linear chirps consistently and uniformly broaden the SBS gain spectrum, achieving a high SBS threshold. This prompted the design of a chirp-like signal by advanced processing and editing of the initial piecewise parabolic signal. A chirp-like signal, differing from the established piecewise parabolic signal, demonstrates similar linear chirp behavior. This characteristic minimizes the required driving power and sampling rate, promoting more efficient spectral spreading. The three-wave coupling equation provides the theoretical basis for constructing the SBS threshold model. Evaluating the chirp-like signal's impact on the spectrum, relative to flat-top and Gaussian spectra, in terms of SBS threshold and normalized bandwidth distribution demonstrates a significant improvement. An experimental validation process is underway, utilizing a watt-class amplifier with an MOPA architecture. The seed source, modulated by a chirp-like signal, demonstrates a 35% enhancement in SBS threshold at a 3dB bandwidth of 10GHz when compared to a flat-top spectrum, and a 18% improvement when compared to a Gaussian spectrum. Its normalized threshold is also the highest. Our findings suggest that the SBS suppression effect is not confined to spectral power distribution alone, but also demonstrably improved via time-domain manipulation. This discovery paves the way for a new method to assess and augment the SBS threshold in narrow-linewidth fiber lasers.

Radial acoustic modes in a highly nonlinear fiber (HNLF), when used to induce forward Brillouin scattering (FBS), allow for acoustic impedance sensing, exceeding 3 MHz in sensitivity, to the best of our knowledge, for the first time. High acousto-optical coupling in HNLFs leads to pronounced increases in the gain coefficient and scattering efficiency of both radial (R0,m) and torsional-radial (TR2,m) acoustic modes in comparison to their counterparts in standard single-mode fibers (SSMFs). A more pronounced signal-to-noise ratio (SNR) is achieved, which consequently enhances the sensitivity of measurements. R020 mode in HNLF produced a considerably higher sensitivity, reaching 383 MHz/[kg/(smm2)], compared to the 270 MHz/[kg/(smm2)] sensitivity observed in SSMF utilizing R09 mode, which exhibited nearly the highest gain coefficient. Sensitivity measurements with the TR25 mode in HNLF registered 0.24 MHz/[kg/(smm2)], exceeding the sensitivity of the same mode in SSMF by a factor of 15. The improved sensitivity of FBS-based sensors improves the accuracy of their external environment detection capabilities.

Mode division multiplexing (MDM) techniques, weakly-coupled and supporting intensity modulation and direct detection (IM/DD) transmission, are a promising method to amplify the capacity of applications such as optical interconnections requiring short distances. Low-modal-crosstalk mode multiplexers/demultiplexers (MMUX/MDEMUX) are a crucial component in these systems. 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. 4-LP-mode MMUX/MDEMUX pairs were fabricated using side-polishing techniques, incorporating cascaded mode-selective couplers and orthogonal combiners. The outcome is a remarkably low modal crosstalk, under -1851 dB, and insertion loss below 381 dB, uniformly across all four modes. Experimental results confirm the stable real-time transmission of 4-mode 410 Gb/s MDM-wavelength division multiplexing (WDM) over 20 km of few-mode fiber. For practical implementation of IM/DD MDM transmission applications, the proposed scheme is scalable, supporting more modes.