This research paper delves into the energy-conscious routing design for satellite laser communication, and also presents the satellite aging model. Based on the model's findings, a genetic algorithm is utilized to develop an energy-efficient routing scheme. By employing the proposed method instead of shortest path routing, satellite lifetime is enhanced by approximately 300%, resulting in only slight network performance deterioration. Specifically, the blocking ratio increases by 12% and service delay by 13 milliseconds.
Metalenses equipped with extended depth of focus (EDOF) enlarge the capturable image range, unlocking novel applications for microscopy and imaging. Despite the presence of limitations, such as an asymmetric point spread function (PSF) and unevenly distributed focal spots, in existing forward-designed EDOF metalenses, which degrades image quality, we propose a novel approach employing a double-process genetic algorithm (DPGA) to optimize the inverse design of EDOF metalenses. Through the use of separate mutation operators in successive genetic algorithm (GA) processes, the DPGA methodology shows considerable improvement in identifying the optimal solution across the entire parameter space. 1D and 2D EDOF metalenses operating at 980nm are individually designed through this procedure, both presenting a noticeable improvement in depth of focus (DOF) compared to conventional focal lengths. Additionally, reliable maintenance of a uniformly distributed focal spot guarantees stable imaging quality throughout the longitudinal dimension. The EDOF metalenses proposed have substantial applications in biological microscopy and imaging, and the DPGA scheme's use can be expanded to the inverse design of other nanophotonic devices.
In contemporary military and civil applications, multispectral stealth technology, including the terahertz (THz) band, will become increasingly crucial. Brigimadlin solubility dmso Following a modular design paradigm, two kinds of adaptable and transparent metadevices were fabricated for multispectral stealth, including the visible, infrared, THz, and microwave spectrums. Three crucial functional blocks for infrared, terahertz, and microwave stealth technologies are conceived and fabricated with the aid of flexible and transparent films. 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. With remarkable THz-microwave dual-band broadband absorption, Metadevice 1 displays an average 85% absorptivity in the 0.3 to 12 THz range and a value exceeding 90% in the 91-251 GHz frequency band, effectively supporting 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. Optically transparent, the metadevices maintain their exceptional stealth capabilities in curved and conformal environments. Our work provides a different method for designing and manufacturing flexible transparent metadevices for the purpose of multispectral stealth, particularly for implementation on non-planar 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. 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 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. Further enhancement in resolution is feasible through the utilization of dark-field microsphere-assisted microscopy. This enables the resolution of an Al nanodot array with a nanodot diameter of 65nm and a center-to-center spacing of 125nm, an impossible task using conventional DFM. 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. Brigimadlin solubility dmso The magnified local electric field, acting as a near-field excitation source, bolsters the scattering of the object, thereby improving the resolution of the images.
The substantial retardation demanded by terahertz phase shifters in liquid crystal (LC) devices invariably necessitates thick cell gaps, which in turn noticeably slow down the liquid crystal response. To elevate the response, we virtually demonstrate a novel liquid crystal (LC) switching method for reversible transitions between three orthogonal orientations, encompassing in-plane and out-of-plane alignments, which broadens the array of continuous phase shifts. The in- and out-of-plane switching of this LC configuration is accomplished using two substrates, each incorporating two sets of orthogonal finger electrodes and one grating electrode. The application of a voltage produces an electric field that governs the switching procedures among the three different orientations, enabling a swift response.
Our investigation into single longitudinal mode (SLM) 1240nm diamond Raman lasers encompasses the suppression of secondary modes. Brigimadlin solubility dmso A three-mirror V-shape standing-wave cavity, fitted with an intracavity LBO crystal to reduce secondary mode generation, yielded stable SLM output characterized by a maximum power of 117 watts and a slope efficiency of 349%. The coupling intensity needed to quell secondary modes, specifically those stemming from stimulated Brillouin scattering (SBS), is calculated by us. SBS-generated modes are frequently observed to align with higher-order spatial modes within the beam profile, and these can be mitigated through the implementation of an intracavity aperture. Numerical computations demonstrate a heightened probability of observing higher-order spatial modes in an apertureless V-cavity, in contrast to two-mirror cavities, due to the varied longitudinal mode structures.
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. Because linear chirp seed sources yield a uniform broadening of the SBS gain spectrum, exceeding a high SBS threshold, a chirp-like signal was developed from a piecewise parabolic signal, augmenting it with subsequent editing and processing. The chirp-like signal, unlike the traditional piecewise parabolic signal, shares comparable linear chirp characteristics. This results in decreased driving power and sampling rate requirements, facilitating a more efficient spectral spreading approach. The three-wave coupling equation provides the theoretical basis for constructing the SBS threshold model. A comparison of the spectrum modulated by the chirp-like signal with both flat-top and Gaussian spectra reveals a considerable improvement in terms of SBS threshold and normalized bandwidth distribution. Experimental validation of the design is performed on a watt-class MOPA amplifier. Within a 3dB bandwidth of 10GHz, a chirp-like signal modulation of the seed source boosts its SBS threshold by 35% relative to a flat-top spectrum and by 18% relative to a Gaussian spectrum; notably, its normalized threshold is the highest amongst these. 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.
Employing radial acoustic modes in forward Brillouin scattering (FBS) within a highly nonlinear fiber (HNLF), we have, to the best of our knowledge, demonstrated acoustic impedance sensing, a feat previously unachieved, and reaching sensitivities surpassing 3 MHz. HNLFs, leveraging high acousto-optical coupling, yield radial (R0,m) and torsional-radial (TR2,m) acoustic modes with superior gain coefficients and scattering efficiencies as compared to standard single-mode fibers (SSMFs). This setup yields an augmented signal-to-noise ratio (SNR), ultimately boosting measurement sensitivity. A notable enhancement in sensitivity, reaching 383 MHz/[kg/(smm2)], was achieved through the use of R020 mode in the HNLF system. This superior result contrasts with the 270 MHz/[kg/(smm2)] sensitivity obtained in SSMF with the R09 mode, despite its almost maximal 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. Enhanced sensitivity will elevate the precision of FBS sensor-based external environment detection.
Short-reach applications, such as optical interconnections, stand to gain significantly from the use of weakly-coupled mode division multiplexing (MDM) techniques, which support intensity modulation and direct detection (IM/DD) transmission. The need for low-modal-crosstalk mode multiplexers/demultiplexers (MMUX/MDEMUX) is paramount in these applications. In this paper, we first propose an all-fiber, low-modal-crosstalk orthogonal combining reception scheme for degenerate linearly-polarized (LP) modes, where signals in both degenerate modes are first demultiplexed into the LP01 mode of single-mode fibers, subsequently multiplexed into mutually orthogonal LP01 and LP11 modes of a two-mode fiber, enabling simultaneous detection. A pair of 4-LP-mode MMUX/MDEMUX, built with cascaded mode-selective couplers and orthogonal combiners, were subsequently manufactured using side-polishing techniques. The achieved characteristics include back-to-back modal crosstalk less than -1851 dB and insertion loss below 381 dB across all four modes. A 20-km few-mode fiber experiment successfully demonstrated stable real-time 4-mode 410 Gb/s MDM-wavelength division multiplexing (WDM) transmission. The proposed scheme is scalable, enabling additional operational modes and laying the groundwork for the practical implementation of IM/DD MDM transmission applications.