Space laser communication relies heavily on acquisition technology, which acts as the pivotal node in establishing the communication link. The acquisition phase of traditional laser communication methods is prohibitively long when compared to the real-time transmission requirements of substantial data volumes within a space optical communications network. A novel laser communication system, incorporating a laser communication function and a star-sensitive function, is proposed and developed to enable precise autonomous calibration of the open-loop pointing direction of the line of sight (LOS). The novel laser-communication system, which, to the best of our knowledge, is capable of scanless acquisition in under a second, was validated through theoretical analysis and field experimentation.

Phase-monitoring and phase-control are indispensable features in optical phased arrays (OPAs) for achieving robust and accurate beamforming. This paper presents an on-chip integrated phase calibration system, featuring compact phase interrogator structures and photodiode readout mechanisms implemented within the OPA architecture. Linear complexity calibration, employed in this method, facilitates phase-error correction for high-fidelity beam-steering. In a silicon-silicon nitride photonic stack, a 32-channel optical preamplifier is built, each channel spaced 25 meters apart. The process of readout incorporates silicon photon-assisted tunneling detectors (PATDs), enabling sub-bandgap light detection without impacting the existing manufacturing steps. Subsequent to the model-based calibration, the OPA beam exhibits a sidelobe suppression ratio of -11dB and a beam divergence of 0.097058 degrees at the 155-meter input wavelength. The calibration and adjustment of the system are wavelength-dependent and enable full two-dimensional beam steering, facilitating the generation of arbitrary patterns with an algorithm of low complexity.

We observe the emergence of spectral peaks in a mode-locked solid-state laser that houses a gas cell inside its cavity. Symmetric spectral peaks result from the combined effects of molecular rovibrational transitions, resonant interactions, and nonlinear phase modulation within the gain medium during the sequential spectral shaping process. The superposition of the broadband soliton pulse spectrum with narrowband molecular emissions, induced by impulsive rovibrational excitation, results in the spectral peak formation due to constructive interference. At molecular resonances, the demonstrated laser's spectral peaks, exhibiting a comb-like structure, may provide novel tools for the tasks of ultra-sensitive molecular detection, controlling chemical reactions mediated by vibrations, and creating standards for infrared frequencies.

Planar optical devices of various types have seen substantial progress thanks to metasurfaces in the last ten years. In spite of this, the functions of most metasurfaces are realized in either reflection or transmission, with the other operation remaining unused. Vanadium dioxide, combined with metasurfaces, enables the creation of switchable transmissive and reflective metadevices, as demonstrated in this work. Due to vanadium dioxide's insulating phase, the composite metasurface operates as a transmissive metadevice. When vanadium dioxide transitions to its metallic phase, a reflective metadevice function takes over. The metasurface's operational mode can be modulated, transitioning between transmissive metalens and reflective vortex generator functions, or between transmissive beam steering and reflective quarter-wave plate functions, all triggered by the phase shift in vanadium dioxide, through the careful structuring of the system. Switchable transmissive and reflective metadevices offer potential applications in the fields of imaging, communication, and information processing.

In this letter, a flexible bandwidth compression technique for visible light communication (VLC) systems is introduced, leveraging multi-band carrierless amplitude and phase (CAP) modulation. Subband-wise narrow filtering is applied at the transmitter, coupled with an N-symbol look-up-table (LUT) based maximum likelihood sequence estimation (MLSE) at the receiver. By recording the pattern-specific distortions from inter-symbol-interference (ISI), inter-band-interference (IBI), and the effects of other channels on the transmitted signal, the N-symbol LUT is created. Experimental demonstration of the concept takes place on a 1-meter free-space optical transmission platform. A notable improvement in subband overlap tolerance of up to 42% is evidenced by the proposed scheme, achieving a spectral efficiency of 3 bits/second/Hertz, the optimal result among tested schemes.

Employing a layered structure with multitasking capabilities, a non-reciprocity sensor is proposed, facilitating both biological detection and angle sensing. multilevel mediation By incorporating an asymmetrical layout of varying dielectric materials, the sensor displays non-reciprocal behavior between forward and reverse signals, allowing for multi-dimensional sensing across various measurement scales. The structure forms the foundational basis for the analysis layer's procedures. By utilizing the peak photonic spin Hall effect (PSHE) displacement to guide the injection of the analyte into the analysis layers, a precise distinction of cancer cells from normal cells can be achieved via refractive index (RI) detection on the forward scale. The measurement range, reaching 15,691,662, correlates with a sensitivity (S) of 29,710 x 10⁻² meters per RIU. The sensor, operating in reverse mode, is capable of detecting glucose solutions at 0.400 g/L (RI=13323138). The sensitivity is measured as 11.610-3 meters per RIU. High-precision angle sensing in the terahertz range is enabled by air-filled analysis layers, precisely determining the incident angle of the PSHE displacement peak. Detection ranges cover 3045 and 5065, resulting in a maximum S value of 0032 THz/. US guided biopsy This sensor's capabilities include detecting cancer cells and measuring biomedical blood glucose, while concurrently offering a novel method for angle sensing.

A lens-free on-chip microscopy (LFOCM) system employing partially coherent light emitting diode (LED) illumination, presents a single-shot lens-free phase retrieval (SSLFPR) method. A spectrometer's recorded LED spectrum dictates how LED illumination's 2395 nm finite bandwidth is segmented into quasi-monochromatic components. By integrating the virtual wavelength scanning phase retrieval method with a dynamic phase support constraint, the resolution degradation resulting from the spatiotemporal partial coherence of the light source can be effectively mitigated. Improvements in imaging resolution, accelerated iterative convergence, and substantial artifact reduction result from the nonlinear characteristics of the support constraint. The SSLFPR method's effectiveness in extracting accurate phase information from LED-illuminated samples, including phase resolution targets and polystyrene microspheres, is shown by using a single diffraction pattern. A field-of-view (FOV) of 1953 mm2 within the SSLFPR method is accompanied by a half-width resolution of 977 nm, a performance 141 times better than the conventional method. Our investigation also included imaging of living Henrietta Lacks (HeLa) cells cultured in vitro, further illustrating the SSLFPR's real-time, single-shot quantitative phase imaging (QPI) ability for dynamically changing biological samples. SSLFPR's easy-to-understand hardware, high data transfer rates, and the ability to capture high-resolution images in single frames, make it a desirable solution for diverse biological and medical applications.

A 1-kHz repetition rate is used by a tabletop optical parametric chirped pulse amplification (OPCPA) system based on ZnGeP2 crystals to generate 32-mJ, 92-fs pulses centered at 31 meters. Employing a 2-meter chirped pulse amplifier with a flat-top beam profile, the amplifier reaches an overall efficiency of 165%, exceeding, according to our knowledge, the highest efficiency of any OPCPA at this wavelength. Following the focusing of the output in the air, harmonics up to the seventh order are evident.

A detailed examination of the inaugural whispering gallery mode resonator (WGMR) made from monocrystalline yttrium lithium fluoride (YLF) is presented in this work. SD49-7 research buy Using single-point diamond turning, a disc-shaped resonator is created, showcasing a high intrinsic quality factor (Q) of 8108. Finally, we introduce a novel, as far as our research indicates, method using microscopic imaging of Newton's rings, viewed from the rear of a trapezoidal prism. Using this method, the separation between the cavity and coupling prism can be monitored by evanescently coupling light into a WGMR. Maintaining an exact distance between the coupling prism and the waveguide mode resonance (WGMR) is advantageous for consistent experimental conditions, as precise coupler gap calibration enables fine-tuning of the coupling regime and helps prevent damage due to potential collisions. This procedure is exemplified and discussed using two separate trapezoidal prisms and the high-Q YLF WGMR.

Surface plasmon polariton waves were used to induce and reveal plasmonic dichroism in magnetic materials with transverse magnetization. The effect, a product of the interplay between the two magnetization-dependent components of the material's absorption, is enhanced when plasmon excitation occurs. The plasmonic dichroism, comparable to circular magnetic dichroism, underpins all-optical helicity-dependent switching (AO-HDS). However, it is specific to linearly polarized light, acting on in-plane magnetized films, which are outside the purview of AO-HDS. By means of electromagnetic modeling, we show that laser pulses interacting with counter-propagating plasmons can be used to write +M or -M states in a manner independent of the initial magnetization. The presented method, applicable to ferrimagnetic materials with in-plane magnetization, showcases the phenomenon of all-optical thermal switching, increasing the spectrum of their applications in data storage devices.