Examining energy-saving routing strategies for satellite laser communications, this paper also constructs a satellite aging model. The model serves as the basis for an energy-efficient routing scheme, designed using a genetic algorithm approach. The proposed method, in comparison to shortest path routing, extends satellite lifespan by approximately 300%, while network performance suffers only minor degradation. The blocking ratio sees an increase of only 12%, and service delay is extended by a mere 13 milliseconds.
The extensive depth of field (EDOF) inherent in metalenses provides an increased imaging area, resulting in advanced applications for imaging and microscopy. With existing EDOF metalenses suffering from issues including asymmetric point spread functions (PSF) and non-uniform focal spot distributions, thus impacting image quality, we present a double-process genetic algorithm (DPGA) inverse design approach to address these limitations in EDOF metalenses. Due to the sequential application of varied mutation operators within two genetic algorithm (GA) cycles, the DPGA approach displays remarkable benefits in identifying the ideal solution throughout the entire parameter space. In this method, 1D and 2D EDOF metalenses, operating at a wavelength of 980nm, are separately designed, each showing a notable improvement in depth of field (DOF) in contrast to standard focusing methods. Subsequently, a uniform focal spot is consistently maintained, thereby ensuring stable longitudinal imaging quality. The proposed EDOF metalenses show considerable promise in the fields of biological microscopy and imaging; additionally, the DPGA scheme can facilitate inverse design for other nanophotonic devices.
In contemporary military and civil applications, multispectral stealth technology, including the terahertz (THz) band, will become increasingly crucial. enzyme-linked immunosorbent assay Employing a modular design approach, two adaptable and translucent metadevices were constructed for multispectral stealth, encompassing the visible, infrared, THz, and microwave spectrums. Flexible and transparent films are employed to design, fabricate, and implement three fundamental functional blocks for IR, THz, and microwave stealth applications. Two multispectral stealth metadevices are readily produced using modular assembly, that is, by the incorporation or the removal of concealed functional blocks or constituent layers. Metadevice 1's dual-band broadband absorption across THz and microwave frequencies consistently achieves an average 85% absorptivity between 0.3-12 THz and over 90% absorptivity within the 91-251 GHz spectrum, demonstrating its efficacy for THz-microwave bi-stealth. Metadevice 2, enabling bi-stealth for infrared and microwave signals, displays absorptivity exceeding 90% in the 97-273 GHz range and low emissivity, approximately 0.31, within the 8-14 meter wavelength range. Under conditions of curvature and conformality, both metadevices are both optically transparent and possess a good stealth capacity. An alternate methodology for designing and producing flexible, transparent metadevices for multispectral stealth is proposed by our work, especially for implementation on non-planar surfaces.
We introduce, for the initial time, a surface plasmon-enhanced dark-field microsphere-assisted microscopy system capable of imaging both low-contrast dielectric and metallic objects. We found that using an Al patch array substrate results in better resolution and contrast when imaging low-contrast dielectric objects in dark-field microscopy (DFM), when contrasted against metal plate and glass slide substrates. On three different substrates, the resolution of hexagonally arranged SiO nanodots, each 365 nanometers in diameter, is possible, with contrast ranging from 0.23 to 0.96. Only on the Al patch array substrate are 300-nm-diameter, hexagonally close-packed polystyrene nanoparticles discernible. Using dark-field microsphere-assisted microscopy, resolution can be elevated, allowing for the resolution of an Al nanodot array featuring a 65nm nanodot diameter and 125nm center-to-center spacing, a distinction not attainable via conventional DFM techniques. On an object, the focusing effect of the microsphere, along with surface plasmon excitation, leads to an increase in the local electric field (E-field), exemplified by evanescent illumination. tunable biosensors 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, crucial for providing the necessary retardation in liquid crystal (LC) terahertz phase shifters, invariably contribute to a delayed liquid crystal response. To enhance the response, we virtually demonstrate novel liquid crystal (LC) switching between in-plane and out-of-plane configurations, enabling reversible transitions between three orthogonal orientations, thereby extending the spectrum of continuous phase shifts. 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. An applied voltage initiates an electric field, which compels each transition between the three clear orientation states, enabling a rapid response.
This paper investigates the suppression of secondary modes within the single longitudinal mode (SLM) operation of 1240nm diamond Raman lasers. Chk2InhibitorII Stable single-longitudinal-mode (SLM) output was attained using a three-mirror V-shape standing-wave resonator including an intra-cavity LBO crystal to suppress secondary modes, reaching a maximum output power of 117 W and exhibiting a slope efficiency of 349 percent. The level of coupling is determined to quell secondary modes, particularly those generated by stimulated Brillouin scattering (SBS). The presence of SBS-generated modes in the beam profile frequently correlates with higher-order spatial modes, and the use of an intracavity aperture is a method to diminish these overlapping modes. Numerical calculations highlight the elevated probability of higher-order spatial modes in an apertureless V-cavity, as opposed to two-mirror cavities, this difference stemming from the contrasting longitudinal mode configurations.
In master oscillator power amplification (MOPA) systems, we propose a novel (to our knowledge) driving scheme to combat stimulated Brillouin scattering (SBS), implemented with an external high-order phase modulation. Seed sources utilizing linear chirps consistently broaden the SBS gain spectrum, characterized by a high SBS threshold, leading to the design of a chirp-like signal by further editing and processing of the initial piecewise parabolic signal. While possessing similar linear chirp properties as the traditional piecewise parabolic signal, the chirp-like signal necessitates less driving power and sampling rate, enabling more effective spectral spreading. The three-wave coupling equation forms the basis of the theoretical framework for the SBS threshold model. The spectrum, modulated by the chirp-like signal, is evaluated against flat-top and Gaussian spectra concerning SBS threshold and normalized bandwidth distribution, demonstrating a substantial improvement. The experimental validation procedure is conducted on a watt-class amplifier, employing the MOPA design. At a 3dB bandwidth of 10GHz, the chirp-like signal-modulated seed source exhibits a 35% improvement in SBS threshold compared to a flat-top spectrum, and an 18% improvement compared to a Gaussian spectrum; its normalized threshold is the highest among these configurations. 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.
Forward Brillouin scattering (FBS) in a highly nonlinear fiber (HNLF), utilizing radial acoustic modes, has allowed, to the best of our knowledge, the first demonstration of acoustic impedance sensing, exceeding a sensitivity of 3 MHz. The superior acousto-optical coupling in HNLF results in both radial (R0,m) and torsional-radial (TR2,m) acoustic modes showcasing higher gain coefficients and scattering efficiencies compared to those observed in standard single-mode fibers (SSMFs). Measurement sensitivity is amplified by the improved signal-to-noise ratio (SNR) that this produces. 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. Employing TR25 mode in HNLF, sensitivity was measured at 0.24 MHz/[kg/(smm2)], a figure 15 times higher than that reported when using the same mode in SSMF. Greater accuracy in detecting the external environment is assured by FBS-based sensors with improved sensitivity.
Weakly-coupled mode division multiplexing (MDM) techniques, enabling intensity modulation and direct detection (IM/DD) transmission, are a potential solution to improve the capacity of short-reach optical interconnection applications. The desire for low-modal-crosstalk mode multiplexers/demultiplexers (MMUX/MDEMUX) is considerable in these applications. 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. Employing the side-polishing method, 4-LP-mode MMUX/MDEMUX pairs were produced. These pairs consist of cascaded mode-selective couplers and orthogonal combiners, achieving a remarkably low modal crosstalk of less than -1851 dB and insertion loss of under 381 dB for all four modes. A demonstration of a stable 4-mode 410 Gb/s MDM-wavelength division multiplexing (WDM) transmission system is experimentally accomplished over 20 km of few-mode fiber, achieving real-time performance. The proposed scalable scheme facilitates multiple modes of operation, potentially enabling practical implementation of IM/DD MDM transmission applications.