Automated determination of the sizes, velocities, and 3-dimensional coordinates of nonspherical particles is illustrated by a proposed DHM processing algorithm involving multiple iterations. Two-meter diameter ejecta are successfully tracked, whilst uncertainty simulations indicate the precise quantification of particle size distributions for diameters exceeding 4 meters. Demonstrating these techniques are three explosively driven experiments. Film-based ejecta recordings corroborate newly measured size and velocity statistics, but the data unveils hitherto unknown spatial variations in velocities and 3D locations that require further investigation. Eliminating the cumbersome task of analog film development, the strategies outlined herein promise to substantially accelerate future studies in ejecta physics.
The application of spectroscopy persistently opens up possibilities for a deeper understanding of the fundamental workings of physical phenomena. A pervasive limitation of the dispersive Fourier transformation method for spectral measurement stems from the obligatory temporal far-field detection condition. Building upon the foundation of Fourier ghost imaging, we create an indirect technique for measuring the spectrum, thus exceeding the current limitations. In the time domain, near-field detection and random phase modulation are used to reconstruct the spectrum information. Since all actions happen in the near field, the length of the dispersion fiber and the resulting optical losses are considerably lessened. To ensure optimal performance in spectroscopy, the required length of the dispersion fiber, spectrum resolution, spectral measurement range, and the bandwidth demands of the photodetector are examined.
We formulate a novel optimization strategy that integrates two design requirements to reduce the differential modal gain (DMG) in few-mode cladding-pumped erbium-doped fiber amplifiers (FM-EDFAs). Besides the standard criterion incorporating mode intensity and dopant profile overlap, a secondary criterion is introduced to maintain consistent saturation behavior in all doped regions. These two conditions define a figure-of-merit (FOM) that facilitates FM-EDFA design with reduced DMG, avoiding high computational expenses. We exemplify this methodology through the design of six-mode erbium-doped fibers (EDFs) for amplification within the C-Band, focusing on designs that align with established fabrication procedures. oral bioavailability Fiber structures, characterized by either a step-index or staircase refractive index profile (RIP), incorporate two ring-shaped erbium-doped sections within the core. Our top design, using a staircase RIP, a 29-meter fiber length, and 20 watts of pump power injected into the cladding, exhibits a minimum gain of 226dB, maintaining a DMGmax less than 0.18dB. The optimization strategy based on FOM results in a robust design with low DMG, performing consistently under diverse signal, pump power, and fiber length conditions.
Extensive study has been dedicated to the dual-polarization interferometric fiber optic gyroscope (IFOG), resulting in impressive performance. tumor cell biology In this investigation, a novel dual-polarization IFOG configuration, based on a four-port circulator, is put forth, effectively mitigating issues of polarization coupling errors and excess relative intensity noise. The experimental study of the short-term sensitivity and long-term drift of a 2km fiber coil with a 14cm diameter demonstrates achievements in angle random walk (50 x 10^-5/hour) and bias instability (90 x 10^-5/hour). Furthermore, the root power spectral density at 20n rad/s/Hz exhibits a near-constant value between 0.001 Hz and 30 Hz. In our view, this dual-polarization IFOG presents itself as the preferred choice for reference-grade IFOG performance.
Through a combination of atomic layer deposition (ALD) and a modified chemical vapor deposition (MCVD) process, this work achieved the fabrication of bismuth-doped fiber (BDF) and bismuth/phosphosilicate co-doped fiber (BPDF). The O band's excitation is effectively covered by the BPDF, as verified through experimental investigation of the spectral characteristics. Results have shown that a diode pumped BPDF amplifier exhibits a gain greater than 20dB over the 1298-1348nm spectral range (50nm). The gain coefficient, approximately 0.5dB/meter, contributed to a maximum gain of 30dB, measured at 1320nm. We also produced different local structures through simulations, finding that the BPDF, in contrast to the BDF, shows a more powerful excited state and has more importance in the O-band. A key consequence of phosphorus (P) doping is the modification of the electron distribution, thereby creating the active bismuth-phosphorus center. O-band fiber amplifier industrialization hinges on the fiber's remarkably high gain coefficient.
A differential Helmholtz resonator (DHR) photoacoustic cell (PAC) was used to develop a near-infrared (NIR) hydrogen sulfide (H2S) sensor capable of detecting concentrations down to the sub-ppm level. A central component of the detection system was a NIR diode laser, operating at a center wavelength of 157813nm, coupled with an Erbium-doped optical fiber amplifier (EDFA) delivering 120mW of output power, and a DHR. Utilizing finite element simulation software, an analysis of the DHR parameters' impact on resonant frequency and acoustic pressure distribution within the system was undertaken. The volume of the DHR was determined, through simulation and comparison with the conventional H-type PAC, to be one-sixteenth its volume, keeping resonant frequency the same. Evaluation of the photoacoustic sensor's performance followed optimization of the DHR structure and modulation frequency. The sensor's linear response to gas concentration was clearly demonstrated by experimental results. The differential mode enabled the detection of H2S with a minimum detection limit (MDL) of 4608 parts per billion.
An experimental methodology is used to examine the generation process of h-shaped pulses in a mode-locked fiber laser, featuring all-polarization-maintaining (PM) and all-normal-dispersion (ANDi) characteristics. The generated pulse, in contrast to a noise-like pulse (NLP), is proven to be unitary. Further, the h-shaped pulse, with external filtering, is resolvable into rectangular pulses, chair-shaped pulses, and Gaussian pulses. Unitary h-shaped pulses and chair-like pulses, displaying a double-scale structure, are seen on the autocorrelator in the authentic AC traces. The chirp of an h-shaped pulse displays a demonstrably similar form to the characteristic chirp observed in DSR pulses. This is the initial observed instance of unitary h-shaped pulse generation, as far as our knowledge extends. Our experimental results, it is found, reveal a tight correlation between the formation mechanisms of dissipative soliton resonance (DSR) pulses, h-shaped pulses, and chair-like pulses, ultimately integrating the concepts behind such DSR-like pulses.
Shadow casting plays a vital role in computer graphics, contributing to the overall sense of reality in rendered visuals. Polygon-based computer-generated holography (CGH) typically avoids in-depth investigation of shadowing, as current state-of-the-art triangle-based occlusion techniques are unnecessarily complex for shadow calculations and inadequate for handling intricate cases of mutual occlusion. The analytical polygon-based CGH framework served as the foundation for a novel drawing method that addressed occlusion using a Z-buffer approach, rather than the conventional Painter's algorithm. The addition of shadow casting to parallel and point light sources was also achieved. Our framework, generalizable to N-edge polygon (N-gon) rendering, can be significantly accelerated through the utilization of CUDA hardware, enhancing its rendering speed.
We report the impressive 433mW output of a bulk thulium laser operating on the 3H4 3H5 transition pumped by an ytterbium fiber laser at 1064nm. Targeting the 3F4 3F23 excited-state absorption (ESA) transition of Tm3+ ions, the laser exhibited linear polarization. The slope efficiency of 74%/332% (relative to incident/absorbed pump power) marks the highest output ever from a 23m bulk thulium laser using upconversion pumping. The gain material is a Tm3+-doped potassium lutetium double tungstate crystal. Using the pump-probe method, the polarized near-infrared ESA spectra of this material are quantified. The study of dual-wavelength pumping at 0.79 and 1.06 micrometers investigates potential advantages, particularly highlighting that co-pumping at 0.79 micrometers contributes to lowering the upconversion pumping's threshold power.
Nanoscale surface texturization using femtosecond laser-induced deep-subwavelength structures has garnered significant interest. A more comprehensive understanding of the factors influencing formation and the control of timeframes is required. We detail a method of non-reciprocal writing, achieved through a custom optical far-field exposure. This method features ripples with varying periods depending on the scanning direction. A continuous period manipulation from 47 to 112 nanometers (with a 4 nm step) is demonstrated for a 100-nanometer-thick indium tin oxide (ITO) layer on glass. Employing a full electromagnetic model, capable of nanoscale precision, the redistributed localized near-field was demonstrated across multiple ablation stages. MZ-101 nmr Ripple formation is explained, while the asymmetric focal spot is responsible for the non-reciprocity in ripple writing. Through the combined application of beam shaping and an aperture-shaped beam, we were able to produce non-reciprocal writing effects, with respect to the scanning direction. Precise and controllable nanoscale surface texturing is anticipated to find new avenues of exploration through non-reciprocal writing.
A miniaturized diffractive/refractive hybrid system, composed of a diffractive optical element and three refractive lenses, was demonstrated in this paper for solar-blind ultraviolet imaging spanning the 240-280 nanometer range.