Employing a mixed stitching interferometry method, this work corrects for deviations using one-dimensional profile data. This approach rectifies stitching angle errors among various subapertures by employing relatively precise one-dimensional mirror profiles, analogous to those produced by a contact profilometer. A simulation and analysis are performed to determine the accuracy of the measurements. Multiple one-dimensional profiles, each measured at a different position, are utilized and averaged together to reduce the error in repeatability. Last, but not least, the measurement results from the elliptical mirror are presented and assessed against the global algorithm-based stitching, bringing about a one-third reduction in the error of the original profiles. The observed outcome highlights the method's success in limiting the buildup of stitching angle errors within standard global algorithm-based stitching procedures. The accuracy of this method can be augmented by utilizing highly precise one-dimensional profile measurements, including those from the nanometer optical component measuring machine (NOM).
The prevalence of plasmonic diffraction gratings in various applications underscores the need for a method of analysis that accurately models the performance of devices designed using these structures. An analytical technique, apart from markedly diminishing simulation time, proves beneficial in the design process of these devices, enabling performance predictions. In contrast to the effectiveness of numerical methods, analytical techniques confront a significant hurdle in improving the precision of their outcomes. A one-dimensional grating solar cell's transmission line model (TLM) has been modified to include diffracted reflections for a more precise assessment of TLM results. Diffraction efficiencies are accounted for in the development of this model, which was designed for TE and TM polarizations at normal incidence. A modified TLM model, applied to a silicon solar cell with silver gratings of varying widths and heights, reveals the significant influence of lower-order diffractions in improving the model's accuracy. Higher-order diffractions, in contrast, result in converged outcomes. By comparing its outputs with full-wave numerical simulations utilizing the finite element method, the accuracy of our proposed model has been confirmed.
Active terahertz (THz) wave control is demonstrated using a hybrid vanadium dioxide (VO2) periodic corrugated waveguide, the method described herein. Unlike liquid crystals, graphene, semiconductors, and other active materials, vanadium dioxide (VO2) demonstrates a distinctive insulator-to-metal transition triggered by electric fields, optical, and thermal stimuli, leading to fluctuations in conductivity spanning five orders of magnitude. Our parallel waveguide structure consists of two gold-coated plates, on which periodic grooves embedded with VO2 are placed, with their groove sides facing one another. Mode transitions in the waveguide are modeled as a consequence of conductivity changes in the embedded VO2 pads, with the explanation rooted in the localized resonance induced by defect modes. In practical applications like THz modulators, sensors, and optical switches, a VO2-embedded hybrid THz waveguide proves advantageous, offering a novel method for manipulating THz waves.
We scrutinize spectral broadening in fused silica through experimental means, concentrating on the multiphoton absorption range. In the context of supercontinuum generation, linear polarization of laser pulses is more desirable under standard laser irradiation conditions. Circularly polarized light, whether Gaussian or doughnut-shaped, exhibits heightened spectral broadening in the presence of high non-linear absorption. Laser pulse transmission measurements and observation of the intensity-dependent self-trapped exciton luminescence are employed to investigate multiphoton absorption in fused silica. The pronounced polarization sensitivity of multiphoton transitions directly contributes to spectrum broadening in solids.
Research using both simulated and practical scenarios has shown that accurately aligned remote focusing microscopes display lingering spherical aberration beyond the focused plane. The correction collar on the primary objective, driven by a high-precision stepper motor, compensates for residual spherical aberration in this work. A Shack-Hartmann wavefront sensor validates the congruence between the spherical aberration created by the correction collar and the forecast made by the objective lens's optical model. A review of the restricted effect of spherical aberration compensation on the remote focusing system's diffraction-limited range considers on-axis and off-axis comatic and astigmatic aberrations, inherent properties of these microscopes.
The substantial development of optical vortices, imbued with longitudinal orbital angular momentum (OAM), highlights their powerful role in particle control, imaging, and communication. We introduce a novel characteristic of broadband terahertz (THz) pulses. It's characterized by a frequency-dependent orbital angular momentum (OAM) orientation, shown in the spatiotemporal domain with both transverse and longitudinal OAM projections. A two-color vortex field, exhibiting broken cylindrical symmetry and driving plasma-based THz emission, is used to showcase a frequency-dependent broadband THz spatiotemporal optical vortex (STOV). We utilize time-delayed 2D electro-optic sampling in conjunction with Fourier transform analysis to detect the temporal evolution of OAM. Exploring the tunability of THz optical vortices within the spatiotemporal domain yields new methods for analyzing STOV and plasma-based THz radiation.
A theoretical model for a cold rubidium-87 (87Rb) atomic assembly, integrating a non-Hermitian optical design, shows how a lopsided optical diffraction grating is attainable through a single spatially periodic modulation and loop-phase. Variations in the relative phases of the applied beams determine whether parity-time (PT) symmetric or parity-time antisymmetric (APT) modulation is active. The stability of PT symmetry and PT antisymmetry in our system, irrespective of coupling field amplitudes, allows for the precise modulation of optical response without any symmetry violation. Our optical scheme exhibits some noteworthy properties, including asymmetrical diffraction patterns, such as lopsided diffraction, single-order diffraction, and asymmetric Dammam-like diffraction. Our research will contribute to the creation of diverse non-Hermitian/asymmetric optical devices.
A signal-activated magneto-optical switch with a 200 picosecond rise time was successfully demonstrated. The switch leverages current-induced magnetic fields to modify the magneto-optical effect's response. biocybernetic adaptation To accommodate high-speed switching, impedance-matching electrodes were engineered for applying high-frequency current. A torque, originating from a static magnetic field, orthogonal to the current-induced fields, created by a permanent magnet, facilitates the reversal of the magnetic moment, accelerating the process of high-speed magnetization reversal.
For future quantum technologies, nonlinear photonics, and neural networks, low-loss photonic integrated circuits (PICs) are vital components. Multi-project wafer (MPW) fabrication facilities readily employ low-loss photonic circuits for C-band applications, whereas near-infrared (NIR) photonic integrated circuits (PICs), suited for current-generation single-photon sources, remain less advanced. metastatic infection foci This study details the process optimization and optical characterization of low-loss, tunable photonic integrated circuits for single-photon work in a laboratory setting. Gilteritinib We have measured the lowest propagation losses to date, specifically 0.55dB/cm at a 925nm wavelength, in single-mode silicon nitride submicron waveguides with a range of 220-550nm. The performance is enabled by utilizing advanced e-beam lithography and inductively coupled plasma reactive ion etching steps. The resultant waveguides possess vertical sidewalls with a sidewall roughness reaching down to a minimum of 0.85 nanometers. A chip-scale, low-loss photonic integrated circuit (PIC) platform, arising from these results, could be further optimized by incorporating high-quality SiO2 cladding, chemical-mechanical polishing, and multistep annealing processes to meet the exacting demands of single-photon applications.
Employing computational ghost imaging (CGI), we develop a new imaging procedure, feature ghost imaging (FGI), which transmutes color information into distinguishable edge features in the recovered grayscale imagery. FGI, leveraging edge features derived from diverse ordering operators, allows for the acquisition of both shape and color information from objects in a single detection round, employing a single-pixel detector. Numerical simulations illustrate the spectral variations of rainbow colors, and experiments ascertain the practical application of FGI. With FGI, we furnish a new way of imaging colored objects, extending the capabilities and application areas of traditional CGI, all while retaining a straightforward experimental process.
We delve into the behavior of surface plasmon (SP) lasing in gold gratings, fabricated on InGaAs wafers with a periodicity near 400nm. The SP resonance's proximity to the semiconductor energy gap drives efficient energy transfer processes. The optical pumping of InGaAs to the necessary population inversion for amplification and lasing phenomena leads to SP lasing at particular wavelengths, with the grating period dictating the SPR condition. To investigate the carrier dynamics in semiconductor materials and the photon density in the SP cavity, time-resolved pump-probe measurements and time-resolved photoluminescence spectroscopy measurements were respectively utilized. Results show a strong correlation between the evolution of photons and carriers, specifically, an acceleration of the lasing process as the initial gain, which is proportional to the pumping power, grows. This outcome is adequately represented by the rate equation model.