Optics express最新文献

Stabilized narrow-linewidth laser sources and soliton microcombs based on self-injection locking have driven revolutionary advancements from metrological to astronomical applications. Recently, coupled cavities have shown critical significance in optical frequency comb generation, particularly in achieving high conversion efficiency and enabling the formation of ultra-broadband soliton microcombs. In this work, we have developed a methodology for investigating self-injection locking in a laser diode-coupled-cavity system with Rayleigh backscattering. We have derived a set of rate equations to describe the system, obtained the analytical expression for effective detuning, and analyzed the critical coupling conditions and locking range for the coupled cavities. The analytical and numerical simulation results demonstrate that when the coupled-cavity structures induce mode splitting, the self-injection locking system exhibits dual-mode locking behavior. Furthermore, the auxiliary cavity introduces additional phase and losses to the coupled cavity, and the physical explanation for resonance splitting arises from the phase-balancing effect of pump detuning on the additional phase. On the other hand, the losses introduced by the auxiliary cavity can be effectively compensated by tuning the coupling strength between the waveguide and the main cavity. Therefore, we have also derived an analytical expression for the critical coupling coefficient in such laser diode-coupled-cavity systems. The proposed method can be extended to investigate self-injection locking in multi-coupled-cavity systems and provides a theoretical foundation for the realization of stabilized multi-frequency narrow-linewidth laser sources and high-efficiency, broadband soliton microcombs.

A method combining an optimized deskew filter based on a peak-seeking algorithm and an image denoising based on Gaussian filtering was proposed, enabling a strain sensing with a spatial resolution of 5 cm over a measurement range of 1.68 km. In the optimized deskew filter method, the accurate estimation of the nonlinear phase was improved by third-order Taylor expansion and high-accuracy estimation of the time delay in the auxiliary interferometer using a peak-searching method. By employing an optimized deskew filter based on the peak-searching method, the amplitude and width of the peak located at 1212.16 m were improved from 5.9 dB and 45 cm to 14.4 dB and 7 cm, respectively. The strain distribution at 1212 m could be clearly identified at a spatial resolution of 5 cm with the Gaussian filtering-based image denoising method, when the strain was increased from 500 to 2000 µε.

We report the physical realization and validation of a switchable optical element based on a digitized optofluidic platform previously introduced as an approach to switching between two optical powers. There are numerous applications for switching between different optical powers, with presbyopia correction being one of them. The prototype's ultimate intention is for spectacle lens placement in smart and conventional glasses for switching between refractive and diffractive optical states designed to correspond to near and distance foci. In the current prototype development cycle, we looked into remaining deficiencies of the prototype construction to achieve reliable switching between the optical states. We have also investigated the possibility of controlling the switching remotely. The investigation resulted in the introduction of the refractive optical substrate in addition to the diffractive optical substrate, and resulted in a negative outcome on the use of remote control switching in the form of magnetic force. The position and movement of both optical substrates must be more rigorously controlled for fast switching.

In this work, the photoinduced electron transfer was used as a principle to prepare a series of fiber-optic pH sensors, and the reference sensor was prepared by modifying the functional group and adjusting the film-forming matrix to alter steric hindrance. The pH indicator's sensitivity has been regulated. The surface of the optical fiber was chemically modified with the pH indicator via chemical bonding to enhance the performance of sensor 5. Sensors 5 and 4 formed the ratiometric pH sensor. The experimental results indicated that pH sensitivity can be regulated, and the manufactured sensors are promising for pH detection.

We propose what we believe to be a novel non-mechanical eyebox (EB) control optical system for aerial imaging by retro-reflection (AIRR) integrated with virtual reality (VR) head-mounted display (HMD) optics, eliminating the need for the user to wear an HMD. This technology enhances the user's positional freedom. To demonstrate the concept, we employ a Pancharatnam Berry phase diffraction grating (PBP-DG) as a one-dimensional (1D) EB position-shifting device and fabricate a demonstrator. Experimental results confirm that the demonstrator successfully shifts the EB approximately 8 mm in the horizontal direction using a PBP-DG located 30 mm away from the VR HMD optics. Furthermore, we confirm that the virtual image distance can be varied depending on the distance between the display and the VR HMD optics.

Wavefront correction under dynamic atmospheric turbulence is essential for achieving high-speed and high-fidelity optical communication and imaging. However, the rapidly varying phase distortions caused by turbulence pose significant challenges to conventional adaptive optics systems and supervised learning-based compensation methods. In this paper, we propose a self-supervised predictive Zernike phase inversion network (SS-PZPIN) that integrates dual-intensity Fresnel-consistent inversion and temporal prediction within a physics-informed learning framework. The network reconstructs Zernike coefficients directly from paired intensity distributions and predicts their temporal evolution without relying on labeled phase data. This self-supervised learning paradigm effectively bridges optical propagation physics with data-driven prediction. Simulation results demonstrate that SS-PZPIN achieves over 25% improvement in phase correction accuracy under strong turbulence and maintains more than 100% higher fidelity than the traditional Gerchberg-Saxton algorithm under 2.5-5 ms control delays, with an inference time of 2.67 ms. Furthermore, the model exhibits strong generalization to different turbulence conditions and temporal variations. These results confirm that SS-PZPIN provides a scalable and interpretable approach for real-time adaptive optics and turbulence-resilient free-space optical communication systems.

Achieving multispectral camouflage compatible across laser, infrared (IR), and microwave bands is a pivotal challenge for advanced optoelectronic systems, yet its development has been fundamentally hindered by a longstanding paradox: severe heat accumulation caused by essential electromagnetic absorption inevitably compromises infrared stealth. Current strategies often suffer from performance trade-offs or structural complexity. Here, we propose and numerically demonstrate a hierarchical metasurface that resolves this conflict via a mechanism-decoupling strategy, enabling synergistic laser-IR-microwave stealth with built-in thermal management. The upper laser-IR layer employs coupled plasmonic resonances to achieve >0.99 absorption at 1.064 μm, maintain low emissivity (<0.2) within the 3-5 μm and 8-14 μm atmospheric windows, and simultaneously provide selective high emission (>0.8) in the 5-8 μm non-atmospheric window for radiative cooling. The lower radar layer incorporates genetically-optimized, polarization-insensitive Pancharatnam-Berry phase coding elements, delivering >10 dB monostatic radar cross-section reduction from 12 to 20 GHz. Full-wave simulations confirm that this integrated design effectively tackles the "absorption-heating" paradox endemic to conventional stealth materials. The microwave stealth performance is experimentally validated using fabricated prototypes. This work provides a scalable platform to overcome the thermal management bottleneck in multispectral camouflage and offers new insights into the design of integrated photonic devices requiring multifunctional electromagnetic and thermal control.

We investigated the photovoltaic effects induced by optical vortex irradiation in a GaAs/AlGaAs two-dimensional electron system under quantum Hall conditions in a high magnetic field at cryogenic temperatures. The absence of electron backscattering with a long energy-relaxation length characterizes the transport of electrons through the edge states in quantum Hall electron systems, where the photocurrent is transported to the electrodes placed sufficiently far away from the illuminated spot. The topological charge m dependence on the photovoltaic effect was investigated using perfect vortices for photovoltage change. A clear difference was observed between the optical vortices with m = ±1 and ±3 and those with m = ±2 and ±4. This suggested that the parity of m has different effects on photoexcitation and/or electron transport through the edge states in the quantum Hall electron system. The observed dependence of the photocurrent on the topological charge is attributed to the eddy current due to interband electron excitation by the optical vortices.

Compared with Hermitian theory, non-Hermitian physics offers a fundamentally different mathematical framework, enabling the observation of topological phenomena that have no analogue in Hermitian systems. Among these, the exceptional ring - a ring of exceptional points (EP) - stands out as a quintessential topological feature unique to non-Hermitian systems. In this study, we employ single-photon interferometry to overcome the experimental challenge of precise phase control in quantum systems, thereby enabling a full simulation of the non-Hermitian exceptional ring in the three-dimensional parameter space, while also validating, at the experimental level, the symmetry assumptions required for the measurement. Moreover, we explicitly demonstrate the coherent dynamical evolution of the system, which constitutes a clear manifestation of its quantum nature. By measuring the dynamics in parameter space and mapping them onto reciprocal space, we determine the system's eigenstates, which allows us to characterize the topological band structure of the system under different conditions. We describe the topological properties of the exceptional ring by extracting the Chern number and Berry phase for different parameter manifolds and observe the topological critical phenomena of the system. Moreover, our experimental approach can be extended to probe higher-order EP topologies. Our work paves the way for further exploration of topological non-Hermitian systems.

High-precision phase retrieval in digital speckle pattern interferometry is fundamentally limited by speckle decorrelation noise, which degrades measurement reliability in complex environments. Although various suppression strategies have been proposed, a systematic understanding of their statistical characteristics remains incomplete. This study establishes an analytical model that reveals the intrinsic relationship between the statistical distribution of decorrelation noise and the complex correlation coefficient of speckle fields before and after displacement. The model considers key factors, including out-of-plane displacement, in-plane translation, and the system point spread function. Theoretical predictions were verified through diffraction-limited simulations and optical experiments, in which a precision rotation stage and a differential micrometer platform introduced controlled displacement. The analytical and experimental results demonstrate excellent agreement and clarify the mechanisms of speckle decorrelation in digital speckle pattern interferometry.