By employing the bound states in the continuum (BIC) modes of a Fabry-Pérot (FP) type, this work demonstrates a new design strategy for achieving this target. A spacer layer of low refractive index, separating a high-index dielectric disk array, featuring Mie resonances, from a highly reflective substrate, results in the formation of FP-type BICs due to destructive interference between the disk array and its mirror image in the substrate. strip test immunoassay By thoughtfully designing the buffer layer's thickness, one can produce quasi-BIC resonances characterized by ultra-high Q-factors exceeding 10³. Exemplifying this strategy is an efficient thermal emitter, emitting at 4587m wavelength, characterized by near-unity on-resonance emissivity and a full-width at half-maximum (FWHM) less than 5nm, despite metal substrate dissipation. This research introduces a thermal radiation source with unprecedented ultra-narrow bandwidth and high temporal coherence, making it economically viable for practical applications compared to existing infrared sources made from III-V semiconductors.
Calculating aerial images in immersion lithography necessitates the simulation of thick-mask diffraction near-field (DNF). The use of partially coherent illumination (PCI) is a crucial element in modern lithography tools, boosting pattern accuracy. It is crucial to precisely simulate DNFs in the context of PCI. This paper extends the learning-based thick-mask model, previously developed under coherent illumination, to accommodate partially coherent illumination conditions. The established DNF training library under oblique illumination relies on the detailed modeling offered by a rigorous electromagnetic field (EMF) simulator. An evaluation of the proposed model's simulation accuracy is performed, incorporating mask patterns with differing critical dimensions (CD). Under PCI conditions, the proposed thick-mask model exhibits high-precision in DNF simulations, making it appropriate for applications in 14nm or larger technology nodes. ML385 order By comparison, the proposed model's computational performance demonstrates a speed gain of up to two orders of magnitude, contrasting sharply with the EMF simulator.
Conventional data center interconnects employ substantial arrays of discrete wavelength laser sources that consume a significant amount of power. Yet, the increasing demand for broader bandwidth presents a formidable obstacle to the pursuit of power and spectral efficiency in data center interconnects. Multiple laser arrays in data center interconnect systems can be supplanted by Kerr frequency combs, which are engineered using silica microresonators, thereby reducing the associated strain. Employing a silica micro-rod-based Kerr frequency comb light source, our experiments yielded a bit rate of up to 100 Gbps over a 2km short-reach optical interconnect, showcasing 4-level pulse amplitude modulation signal transmission. Non-return-to-zero on-off keying modulation, used in data transmission, is shown to result in a 60 Gbps capacity. A silica micro-rod resonator-based Kerr frequency comb light source is responsible for producing an optical frequency comb in the optical C-band, with an inter-carrier spacing of 90 GHz. Data transmission relies on frequency-domain pre-equalization to correct amplitude-frequency distortions and the constrained bandwidths of electrical system components. The application of offline digital signal processing elevates the attainability of results, employing post-equalization through feed-forward and feedback taps.
Over the last several decades, artificial intelligence (AI) has permeated numerous subfields of physics and engineering. Within the context of artificial intelligence, this work explores model-based reinforcement learning (MBRL), a critical branch of machine learning, for the control of broadband frequency-swept lasers in frequency-modulated continuous-wave (FMCW) light detection and ranging (LiDAR). We designed a model for the frequency measurement system, which takes into account the direct interaction between the optical system and the MBRL agent, and is grounded in experimental observations and the system's inherent non-linearity. Recognizing the difficulty inherent in this high-dimensional control task, we posit a twin critic network, based on the Actor-Critic framework, to facilitate the learning of the complex dynamic characteristics of the frequency-swept process. In addition, the proposed MBRL layout would contribute to a vastly more stable optimization procedure. During neural network training, a policy update delay strategy and a smoothing regularization technique for the target policy are implemented to improve network stability. With the agent's expertly trained control policy, modulation signals are generated that are both excellent and regularly updated, enabling precise control of the laser chirp, and consequently yielding a superior detection resolution. Our study demonstrates the feasibility of integrating data-driven reinforcement learning (RL) with optical system control, resulting in reduced system complexity and a faster investigation and optimization of control parameters.
Utilizing a robust erbium-doped fiber femtosecond laser combined with mode filtering through newly developed optical cavities and broadband visible comb generation via a chirped periodically poled LiNbO3 ridge waveguide, we have created a comb system with a 30 GHz mode spacing, 62% wavelength availability in the visible region, and nearly 40 dB of spectral contrast. In addition, this system is expected to manifest a spectrum that exhibits little alteration over 29 months. Our comb's properties are designed to meet the needs of fields demanding wide-spacing combs, including astronomical studies such as exoplanet exploration and verifying the accelerating cosmic expansion.
This study investigated the degradation of AlGaN-based UVC LEDs subjected to constant temperature and constant current stress, lasting up to 500 hours. In each degradation stage, comprehensive testing and analysis of the two-dimensional (2D) thermal maps, I-V curves, and optical output powers of UVC LEDs were executed, utilizing focused ion beam and scanning electron microscope (FIB/SEM) to investigate the properties and failure mechanisms. The results of stress-related tests taken before and during the application of stress show that rising leakage current and generated stress-induced defects boost non-radiative recombination early in the stress period, thereby reducing optical power. A fast and visual approach to identifying and analyzing UVC LED failure mechanisms is achieved through the combined use of FIB/SEM and 2D thermal distribution.
Experimental results confirm the efficacy of a universal design for 1-to-M couplers. This is further supported by our demonstration of single-mode 3D optical splitters, utilizing adiabatic power transfer for up to four output channels. Calbiochem Probe IV The fast and scalable fabrication of components is achieved through the use of CMOS-compatible (3+1)D flash-two-photon polymerization (TPP) printing. The optical coupling losses in our splitters have been substantially reduced, below our 0.06 dB measurement sensitivity, by strategically altering the coupling and waveguide geometries. Broadband functionality, spanning nearly an octave from 520 nm to 980 nm, remains with losses under 2 dB. From a fractal, self-similar topology constructed from cascaded splitters, we reveal the efficient scalability of optical interconnects, reaching 16 single-mode outputs with optical coupling losses restricted to a mere 1 decibel.
Silicon-thulium microdisk lasers, integrated in a hybrid fashion using a pulley-coupled structure, are demonstrated to display low lasing thresholds and a broad wavelength emission range. Resonators fabricated on a silicon-on-insulator platform using a standard foundry process have their gain medium deposited via a straightforward, low-temperature post-processing step. We observed lasing in microdisks, with diameters of 40 meters and 60 meters, producing up to 26 milliwatts of double-sided output power. The bidirectional slope efficiencies maximize at 134% with reference to the 1620 nanometer pump power introduced into the bus waveguides. Single-mode and multimode laser emissions spanning the wavelength range of 1825 to 1939 nanometers exhibit thresholds on-chip for pump power below 1 milliwatt. Low-threshold lasers with emission spanning more than 100 nanometers facilitate the creation of monolithic silicon photonic integrated circuits, providing broadband optical gain and highly compact, efficient light sources for the developing 18-20 micrometer wavelength range.
The Raman effect's contribution to beam quality degradation in high-power fiber lasers has garnered considerable attention in recent years, but the precise physical mechanisms responsible for this effect remain unclear. The use of duty cycle operation will distinguish the distinct effects of heat and nonlinearity. A quasi-continuous wave (QCW) fiber laser served as the platform for studying the evolution of beam quality at various pump duty cycles. Observations indicate that a Stokes intensity of -6dB (equivalent to 26% of the signal light's energy) shows no significant effect on beam quality when the duty cycle is at 5%. In contrast, as the duty cycle approaches 100% (CW-pumped), the beam quality degrades increasingly rapidly with escalating Stokes intensity. The IEEE Photon publication's experimental results clash with the core-pumped Raman effect theory. The study of technology. The findings of Lett. 34, 215 (2022), 101109/LPT.20223148999, merit further investigation. The heat gathered within the Stokes frequency shift, as confirmed by further analysis, is strongly suspected to be the cause of this phenomenon. We have, to the best of our knowledge, observed for the first time the intuitive manifestation of the origin of stimulated Raman scattering (SRS) beam quality deterioration at the transverse mode instability (TMI) threshold in an experiment.
Coded Aperture Snapshot Spectral Imaging (CASSI) utilizes 2D compressive measurements to capture 3D hyperspectral images (HSIs).