Optics letters最新文献

Unidirectional electromagnetic modes can be immune to backscattering, as no backward-propagating mode exists in the system. For broadband unidirectional modes (typically supported by uniform guiding structures), an additional striking property may emerge: exotic dispersion, in which a monotonically varying dispersion curve crosses the entire air light cone. However, in the terahertz regime, uniform unidirectional waveguides proposed previously do not exhibit such behavior. In this work, we show that a semiconductor-silicon-opaque medium structure can support a terahertz unidirectional surface magnetoplasmon (USMP) mode with exotic dispersion under certain conditions. We also reveal why previous USMP waveguides do not exhibit exotic dispersion. USMPs with exotic dispersion enable a class of metasurfaces whose extracted phases and amplitudes can be set arbitrarily and continuously. As examples, we numerically demonstrate terahertz wave focusing and Airy-beam radiation.

We report a deep-ultraviolet (DUV) metal-semiconductor-metal (MSM) photodetector based on a β-Ga₂O₃ thin film deposited by chemical vapor deposition (CVD) on a patterned sapphire substrate (PSS), compared with a control device using a film grown on flat sapphire. To the best of our knowledge, this is the first demonstration of β-Ga₂O₃ films with a preferred (510) orientation. The film grown on PSS exhibited high defect densities, including structural disorders, oxygen vacancies, and dangling bonds, which enabled exceptional responsivity (106.5 A/W) and specific detectivity (1.36 × 10¹³ Jones) through strong internal gain and extrinsic transitions, despite a relatively large dark current. A UV/visible rejection ratio (R₂₅₅/R₄₀₀) above 10⁴ further confirmed the device's sensitivity. A comprehensive analysis was performed on the impact of defects on the increased dark current and slower response. These findings offer important insights into the growth mechanism of β-Ga₂O₃ on PSS and highlight its potential for scalable, cost-effective solar-blind photodetectors.

Mueller matrix polarimetry (MMP) is a crucial imaging modality for the anisotropic study of birefringent objects. The major drawback of MMP is that it lacks phase information of the sample. Moreover, the real-time Mueller matrix measurement and associated anisotropy retrieval with desired imaging parameters are substantial challenges in existing MMP techniques. We propose and experimentally demonstrate a novel, to our knowledge, polarization holographic technique enabling simultaneous measurement of spatially resolved intensity, quantitative phase (QP), and polarization properties of anisotropic samples from the linear Mueller matrix by integrating division of focal plane (DoFP) polarimetric sensing and digital holographic microscopy (DHM) from just four recorded holograms, demonstrating a fourfold reduction in acquisition compared to conventional sequential MMP methods. The results exhibit notable edge enhancement features, which are directly associated with the anisotropy of the sample. This technique provides a hybrid approach for fast and cost-efficient Mueller matrix holography with potential applications in birefringent microscopy and clinical diagnosis.

The referenced article [Opt. Lett.50, 4746 (2025)10.1364/OL.564000] has been retracted by the authors.

The independent control of phase channels of the Jones matrix via metasurfaces enables advanced applications in wavefront manipulation and optical encryption. Conventional methods for achieving this control under linear or circular polarization bases typically rely on multilayer metasurfaces or anisotropic chiral structures. Here, we propose a universal strategy for independent control of all four Jones matrix phase channels under linear polarization using a single-layer metasurface. By synergistically combining the beam splitting method with polarization-dependent interference effects, we reconstruct the Jones matrix under linear polarization bases to achieve independent modulation of phase channels. This design is realized with a relatively small number of variable-sized nanostructures and an optimized algorithm, notably requiring only two types of half-wave plates for full phase control. Simulation results demonstrate that the designed metasurface produces four distinct Fourier holograms in arbitrary linear polarization bases, and even under elliptical polarization. This work paves the way for applications in multidimensional polarization control, information encryption, and optical communications.

While quasi-bound states in the continuum (Q-BICs) enable vivid structural colors, their performance is often compromised by higher-order resonances at short wavelengths that limit spectral purity. This paper presents a dual-layer all-dielectric metasurface that overcomes this challenge through refractive index matching. The design not only suppresses short-wavelength resonances but also enhances the far-field coupling of the main resonance. It achieves continuous hue and brightness tuning across the visible spectrum, delivering colors with exceptional monochromaticity (<5 nm FWHM), high saturation (>90%), and a wide gamut covering 150.2% of sRGB. This study provides a robust solution for advanced display, data storage, and anti-counterfeiting applications.

The interplay between Rayleigh backscatter and Kerr nonlinearity has attracted intensive interest. However, strong Rayleigh backscatter, accompanied by mode-splitting, has a negative impact on the formation of soliton microcombs. Here, we propose a local dispersion method to enable the formation of a breathing soliton in the mode-splitting microcavity, demonstrating the energy exchange process between the counter-propagating waves. Besides, we also note that, via locking the oscillated frequency, the repetition rate of the breathing soliton microcomb could be enhanced. Our work paves the way for exploring the soliton dynamics and provides a novel, to the best of our knowledge, method to lock the soliton microcomb.

Optically levitated nanoparticles in vacuum experience both electrostatic and light-induced dipole-dipole interactions, offering a versatile platform to explore mesoscopic entanglement and many-body dynamics. A significant challenge in optical trap arrays is to achieve site-resolved, point-to-point tunability: adjusting the laser parameters of a single trap typically induces global cross-talk to neighboring sites, hindering independent control. Inspired by tunable couplers in superconducting circuits, we implement an ancillary nanoparticle that functions as a coupler between two target nanoparticles. Within a reconfigurable three-particle array, we demonstrate broad tunability of the direct dipole-dipole interaction by controlling the phase and position of the traps. In addition, we observe spectral signatures consistent with mediated interactions between the target particles via the ancillary one, manifested as mode participation beyond the uncoupled response. Our results establish a practical route to tailored, site-resolved control in multi-particle optical trap arrays, expanding the optical-binding toolbox and opening opportunities for programmable oscillator networks relevant to macroscopic quantum mechanics and precision sensing.

Ghost imaging (GI) is a technique for indirectly obtaining object images through the second-order intensity correlation and has been extensively documented. However, it is typically limited to intensity imaging, and phase retrieval requires the introduction of supplementary methods such as interferometers or phase-shifting techniques. Here, a technique is proposed that reconstructs the phase of objects based on the second-order intensity correlation without the supplementary methods. By substituting the zero-mean thermal light in conventional GI with non-zero mean light and employing a point detector to detect the object's higher-order Fourier spectrum, the second-order intensity correlation generates an off-axis hologram, thereby reconstructing the object's phase. This technique eliminates the need for additional methods and demonstrates the feasibility of using solely the second-order intensity correlation for phase imaging, which may contribute to advancing the theory and application of GI in phase imaging.

In this paper, we propose an approach for highly stable radio-frequency (RF) dissemination with suppressed residual phase noise (RPN) based on a wavelength-selective optical reflecting (WSOR) structure. In the proposed system, both the transmitted RF signal and a low-frequency probe signal are jointly fed into a high-speed dual-drive Mach-Zehnder modulator. The generated intensity-modulated optical signal is transmitted from the local site to the remote site over an optical fiber link. At the remote site, the received optical signal is split into two branches, where one is directed to the WSOR structure, which reflects only the optical components corresponding to the probe frequency, while the other is sent to a high-speed photodetector for recovering the transmitted RF signal. This configuration effectively suppresses RPN induced by Rayleigh backscattering. Experimental validation demonstrates an RPN suppression ratio of 13.8 dB at 18 GHz. Moreover, RF signals with tunable frequencies from 14 GHz to 18 GHz are successfully disseminated over a 10-km fiber link. The root-mean-square delay jitter measured over one hour remains below 0.214 ps, confirming the system's exceptional stability. The proposed scheme offers distinct advantages, including low RPN, high stability, and broad transmission bandwidth, making it highly suitable for distributed systems demanding stringent coherence and timing stability.