Optics letters最新文献

We report on heterogeneously integrated continuous-wave (CW) lasers on a SiN platform that employ a microgear as a wavelength-selective reflector. Heterogeneous integration is realized through micro-transfer printing (µTP), enabling compact, robust, and frequency-stable on-chip lasers without the need for phase shifters. The devices achieve up to 12.1 mW of on-chip optical output power and intrinsic linewidths as narrow as 3.7 kHz, highlighting the tradeoff between output coupling and coherence. The laser devices operate in single mode with side-mode suppression ratios exceeding 45 dB, and have a compact footprint of 4000 × 250 µm². These results demonstrate a promising path to integrated lasers for coherent communications and LiDAR.

A novel, to the best of our knowledge, dual-layer deep time-delay reservoir computing (TDRC) is demonstrated based on a single semiconductor ring laser (SRL) using directional mode multiplexing. A single SRL with co-directional optical feedback inherently supports the clockwise (CW) and counter-clockwise (CCW) dynamics with weak interferences between opposite directions. Making use of this property, the CW and CCW reservoirs can be simultaneously achieved based on only one single laser using directional mode multiplexing. To form a deep configuration, the two reservoirs are connected by feeding the CW emission into the CCW direction through counter-directional optical feedback. The computing performances are first evaluated by task-independent indicators, and then further evidenced by popular benchmark tasks. Based on similar hardware resources with a single-layer configuration, the proposed dual-layer deep configuration not only expands the parameter ranges, but also enhances the computing accuracies. This work provides a novel solution to reduce the system complexity of multi-layer deep TDRCs and improve the efficiency of hardware usage.

In this Letter, we propose and demonstrate a low-loss and polarization-insensitive edge coupler based on an etched facet double-tip inverse taper structure in lithium niobate on insulator (LNOI) across the C- and L-bands. Using a simple dry etching process, we have obtained a flat edge facet for fiber coupling, eliminating the need for chip edge polishing. The fabricated edge coupler exhibits a fiber-to-chip coupling loss of 1.28/0.67 dB per facet for TE/TM mode at 1550 nm. The measured coupling loss is lower than 1.5/1.0 dB per facet for TE/TM mode, and the polarization-dependent loss is below 0.85 dB over the 1530-1630 nm wavelength range. This scheme is suitable for wafer-scale production and provides a cost-effective and efficient solution for fiber-to-chip coupling, which will find applications in the LNOI photonic integrated circuits.

Ultrafast laser pulses in the 1.62-1.68 μm wavelength range (U-band) hold significant potential for applications such as spectroscopy, optical communication, and bio-imaging. However, it is challenging to generate high-energy, high-performance ultrafast pulses in the U-band, since it cannot be covered by the emission spectra of well-developed rare-earth ions of erbium and thulium. Herein, we demonstrate a simple and efficient method to generate U-band femtosecond laser pulses by nonlinear optical gain modulation of a 1645 nm single-frequency (SF) laser through stimulated Raman scattering. Near-transform-limited 1645 nm laser pulses were obtained with 2.3 W average power and 234 fs pulse duration at a 102.3 MHz repetition rate and 63.2% conversion efficiency. By tuning the wavelength of the SF laser, this method is expected to enable wavelength-flexible, high-energy ultrafast pulse generation across the entire U-band.

In this work, we develop an ITO-based metasurface integrated with disordered silver nanoparticles (DSNPs). The localized plasmon resonance of the DSNPs couples and confines incident light within the ITO layer, enabling strong nonlinear responses across a broad visible-to-near-infrared spectrum with minimal polarization dependence (with a fluctuation of <15%). At a low pump intensity of 0.2 GW/cm², the ultrathin (∼35 nm) metasurfaces exhibit a nonlinear refractive index exceeding 0.1 cm²/GW, with a maximum value reaching 1.24 cm²/GW. This research provides a solution for low-power, high-integration-density nonlinear nanophotonic devices and all-optical control.

In this work, we developed a high-speed photonic diode based on third-order nonlinearity of tin sulfide nanosheets (SnS NSs) and copper antimony sulfide quantum dots (CAS QDs). The transmission characteristics of this photonic diode are simulated by nonlinear transmission model and experimentally validated by Z-Scan and P-Scan techniques. Significant non-reciprocal transmission is observed, with a maximum non-reciprocal factor (NRF) of 5.78 dB. Furthermore, the diode demonstrates ultrafast response time less than 1 ps at the VIS-NIR band, enabling optical modulation up to hundreds of gigahertz. This work lays a theoretical and experimental foundation for designing novel photonic devices based on stacked low-dimensional materials.

Complementary metal-oxide-semiconductor (CMOS)-compatible photonic integrated circuits (PICs) capable of operating at visible wavelengths are critical for advanced quantum systems, including trapped-ion quantum computers. However, standard silicon (Si) PICs are fundamentally unsuitable for this task due to silicon's strong intrinsic material absorption, which prevents the efficient propagation of visible light in Si waveguides. In this work, we present a hybrid two-dimensional (2D) integrated silicon-on-insulator (SOI) PIC platform that enables out-of-plane visible light emission through second-harmonic generation (SHG). This emission arises from a monolayer tungsten diselenide (WSe₂) with broken inversion symmetry, which is encapsulated within hexagonal boron nitride (hBN) to avoid degradation. Our approach bypasses Si absorption by leveraging the transparency of Si waveguides at the infrared pump wavelength, while nonlinear frequency conversion occurs exclusively in the 2D material at the out-coupling interface to convert the infrared photons into visible light. This work opens a promising pathway toward realizing CMOS-compatible, on-chip visible light sources for quantum technologies.

Low optical loss and high refractive index semiconductor materials are ideal for light-matter interactions at the nanoscale. In this work, we propose a two-dimensional perovskite core and silicon shell structure to study strong coupling between the perovskite exciton and magnetic Mie mode of the silicon shell. Simulations based on the Lorentz dielectric function of perovskite reveal that Mie resonance peaks can be tuned to maintain the dominant magnetic dipole Mie modes, enabling strong coupling with Rabi splitting of about 100 meV. When the experimental dielectric function of 2D perovskite is performed, the Rabi splitting increases to 115 meV. Further tuning of the 2D perovskite core size, silicon shell thickness, and refractive index indicates that the hybrid modes remain in the strong coupling regime. This work provides a strategy for tunable light-matter interactions in nanophotonic devices.

Ghost imaging excels in extreme conditions owing to its exquisite sensitivity and adaptability, yet ambient-light perturbations disrupt the masks and compromise reconstruction fidelity. We propose an uncertainty-aware physics-informed framework that explicitly characterizes target and mask distortions in ambient illumination. By integrating a dual-branch architecture with a progressive training strategy, image reconstruction is disentangled from noise suppression, enhancing stability and fidelity. Comprehensive verification demonstrates that the work alleviates reliance on a precise measurement matrix, achieving high-fidelity imaging in complex lighting and noise interference.

A backward terahertz-wave parametric oscillator (BW-TPO) based on a periodically poled stoichiometric lithium tantalate is developed, offering an alternative to the commonly used periodically poled lithium niobate available, and proving that the BW-TPO can also be generated from other nonlinear optical gain media. With what we believe to be a new material, other such materials could also be established, opening up the BW-TPO for a wider breadth of applications.