Optics letters最新文献

Visible-light interference imaging uses distributed sub-apertures to surpass the diffraction limit, offering a promising approach for large-aperture imaging. Traditional systems are limited by bulky free-space optical paths, while on-chip integration suffers from the lack of high extinction ratio optical switches in the visible spectrum. We propose a two-stage mode management strategy to enhance the extinction ratio. We also optimize the thermal transfer model of the interferometric arm to reduce drive power and response time. The device achieves a 39.9 dB extinction ratio at 532 nm and maintains high phase modulation linearity across the 0 to π (RMSE < 0.0004 rad) and the π to 2π (RMSE < 0.0021 rad) phase shift range. Moreover, relative to a conventional design, the drive power is reduced by 28% and the rise time is reduced by 21%. This device offers a solution for multi-channel parallel interference imaging systems or portable high-resolution imaging devices.

In the semiconductor industry, the requirement for optical systems of high resolution with minimal aberration is becoming more stringent as the wavelength employed in the lithography tool is shortened. Index homogeneity, which is a key property for realizing aberration-free optics, has been conventionally characterized using a Fizeau interferometer with a visible light source. However, this method may not be technically feasible for the assessment of optical materials intended to operate in the ultraviolet (UV) wavelength region due to the steeper dispersion slope in that region. Here, we performed an optical testing for the index homogeneity of a single-crystal CaF₂ optical window, which was grown via Czochralski method, by conducting interferometric measurements in the DUV wavelength region. A home-built DUV Fizeau interferometer was developed and self-calibrated to examine the CaF₂ optical window for at-wavelength measurements. Furthermore, sub-aperture stitching interferometry was implemented to investigate the full aperture index distribution of the CaF₂ optical window. The results were compared with the inhomogeneity measured by a commercial visible-wavelength Fizeau interferometer, which showed a value almost twice as high as that of the visible interferometer.

We theoretically analyze the nonlinear dynamics and routes to chaos in a multimode vertical cavity surface-emitting laser (MM-VCSEL) in free-running operation. Including higher order transverse modes (TMs) results in additional bifurcations at higher currents not found for single-mode VCSELs (SM-VCSELs). The resulting dynamics involve competition between modes with different transverse profiles and polarization and show good qualitative agreement with recent experiments.

Using the Pontryagin maximum principle (PMP), we address the crystal length minimization problem in sum-frequency generation (SFG) under the undepleted pump approximation. Our results show that the minimal crystal length is inversely proportional to the coupling coefficient, and that the optimal evolution trajectory follows a geodesic on the Bloch sphere along which the optical field propagates without energy loss or absorption. The crystal polarization period is derived from the optimal phase-matching function. These findings offer valuable guidance for the design of compact optical chips and nonlinear optical devices.

This publisher's note contains a correction to Opt. Lett.50, 7408 (2025)10.1364/OL.572772.

We present what we believe to be a novel way of utilizing an all-normal dispersion fiber cascade in order to achieve a substantial increase in spectral width for a fixed input pulse, as compared to spectral widths attainable in the individual fibers. We numerically show how this increased spectral width arises due to an asymmetry exhibited by the wave breaking (OWB), allowing for the utilization of the low dispersion regions of both adopted fibers. We investigate how such a cascade may utilize the pulse length as a tunable parameter in order to avoid unrealistically short fiber lengths, while remaining in the low-noise regime. In addition, we show how the OWB asymmetry varies with input peak power and pulse length and how this affects the dynamics of the cascade. Finally, we show how the output of an optimal cascade configuration maintains high coherence and low noise.

Supersymmetric semiconductor lasers, emitting around 1064.0 nm, are designed and fabricated that are based on two cascaded coupled supersymmetric transformations to filter out high-order modes of transverse wide waveguides. Combined with the design of a lateral narrow ridge waveguide with a width of 5.0 μm and a cavity length of 0.5 mm, supersymmetric lasers achieve a single-lobe far-field pattern at the temperature of 25°C, up to an injection current of 250.0 mA, with the continuous-wave output power of 230.0 mW. The maximum efficiency and output power of supersymmetric lasers are 61.4% at an injection current of 80.0 mA, and 276.1 mW at an injection current of 300.0 mA without obvious thermal runover, respectively. Our works offer new insight into mode control of wide waveguides.

We report theoretically polarization-controlled Bloch oscillations in the synthetic two-level photonic system, where the horizontal and vertical polarizations of light emulate pseudospin up and down. We synthesize a magnetic lattice in the light-crystal interaction process and demonstrate directional Bloch oscillations of polarized light, accompanied by the optical Zener tunneling. Within this framework, we study the directional Bloch oscillations with pure spin-up and spin-down, as well as mixing spin, carried by the fundamental Gaussian mode. Furthermore, our formulism can be extended to the higher-order framework, realizing the Bloch oscillation of the topological spin texture. These results show that the Bloch oscillation can be effectively controlled by the incident spin (polarization). We therefore anticipate that the presented framework for the Bloch oscillations can find potential applications. For example, it can be exploited as a polarization-related device for optical information processing.

In this Letter, the photonic time crystal (PTC) is employed to achieve multi-channel angle magnification windows (AMWs) in the angular domain, and further to generate an optical angular comb (OAC). Research indicates that the number and height of AMWs can be precisely controlled by adjusting the parameters of the PTC, where the mathematical relationship between the distribution of AMWs and the ratio of refractive index components and phase of the PTC parameters is provided. By changing the time modulation of the PTC's dielectric tensor from a step change to an approximately smooth change, the width characteristics of the AMWs can be flexibly adjusted. The results are verified and compared using the transfer matrix method and the finite-difference time-domain method, confirming the accuracy of the analysis. The proposed OAC has potential application value in fields such as precision angle measurement and spatial light information processing.

The feasibility of demodulating fiber Bragg grating (FBG) accelerometers using a Michelson interferometer (MI) based on a silicon-on-insulator (SOI) platform, in conjunction with phase demodulation techniques, is experimentally demonstrated. An on-chip MI structure is obtained through the integration of a multimode interferometer (MMI) with waveguide Bragg gratings (WBGs). This on-chip MI exhibits an output spectral bandwidth of 14 nm and a free spectral range (FSR) of 0.84 nm. By employing thermal tuning of the on-chip MI, wavelength division multiplexing was implemented. This work employs phase generated carrier (PGC) demodulation techniques to achieve dynamic demodulation of fiber optic accelerometers (FOAs). The performance of the system is validated by comparing it with a commercial FBG interrogator. The system ultimately demonstrates a dynamic acceleration resolution of 0.204 mg/Hz.