We demonstrate synchronous real-time optical performance monitoring of microcomb-based WDM signals via a Fourier-domain optical vector oscilloscope. Frequencyto-time mapping with chirped coherent detection enables single-acquisition retrieval of multi-channel amplitude and phase information without local oscillator source sweeping. Experimental characterization of 16 × 40 Gbit/s QPSK signals verifies a scalable approach for high-capacity microcombenabled transmission systems.

Optical frequency combs generated in Kerr microcavities offer a promising platform for miniaturizing comb systems. While single-pump configurations have been extensively investigated, dual- and multi-pump schemes provide new degrees of freedom for precisely controlling and tailoring the comb generation dynamics and properties. Here, we demonstrate soliton breathing phenomena induced by co-propagating pumps in the auxiliary-pump-assisted microcomb generation scheme, referred to as parametric beat-driven breathers. These breathers exhibit a unique existence range and a clear dependence on breathing frequency, significantly differing from intrinsic and intermode breather solitons. We experimentally reveal the relationship between the breathing and pump frequencies and a mode-number-dependent distribution of the relative breathing depth across comb lines. Breathing enhancement phenomena triggered by avoided mode crossings are also observed. Theoretical analysis and numerical simulations based on the dual-pump Lugiato-Lefever equation agree with experimental results. Our findings not only uncover critical instability features in co-polarized dual-pump-generated microresonator soliton frequency combs but also fundamentally highlight the necessity of pump architecture optimization for achieving enhanced stability and operational performance in practical Kerr-comb-based photonic systems.

Dissipative Kerr solitons (DKSs) generated in optical microresonators have shown considerable promise across multiple applications, particularly in metrology and spectroscopy. Multistable solitons enable on-chip singlecavity dual-comb generation, and can be excited via multicolor pumping in a microresonator featuring high-quality factor and strong nonlinearity, whose dispersion profile governs the soliton velocity mismatch. However, real-time characterization of complex multistable soliton dynamics remains highly challenging due to their transient nature, large bandwidth, and high repetition rate. In this work, we generate multistable soliton dynamics using a dual-pump scheme targeting distinct cavity modes and report, for the first time, their simultaneous time-and spectral-domain characterization via a chirped coherent detection scheme. These multistable solitons are measured at different carrier-envelope offset frequencies, allowing for the observation of soliton switching and annihilation processes during pump detuning. Furthermore, the gain transfer mechanisms underpinning the influence of pump detuning on soliton dynamics are investigated. This study not only deepens our understanding of complex soliton interactions within optical microresonators but also supports enhanced control and utilization of single-cavity dual-comb sources.

Generating ever-shorter and brighter light pulses is a central goal of ultrafast science, enabling coherent control and observation of electron dynamics on their natural timescale. State-of-the-art isolated attosecond pulse generation currently achieves pulse durations of 40-50 attoseconds. Here we demonstrate isolated attosecond light pulses with durations of 18 attoseconds, via high-order harmonic generation driven by a post-compressed industrial-grade Yb laser system. The high-harmonic spectrum spans photon energies from 50 to 320 eV, covering the carbon K-edge, with a calibrated photon flux exceeding 1012 photons per second. Pulse durations were characterized by angle-resolved photoelectron streaking in helium and optimized using a series of filters with different thicknesses to compensate the attochirp. We further developed a robust, fast-converging pulse-retrieval algorithm capable of reconstructing broadband isolated attosecond pulses and double pulses. These results establish Yb-laser-driven high-order harmonic generation as a powerful platform for bright isolated attosecond sources and next-generation ultrafast spectroscopy.

Optical frequency combs generated in high-Q microresonators have unique applications, and the precise dispersion measurement is crucial to the research and design of microresonators and the generation of optical frequency combs. Here, we demonstrate a dispersion measurement method for the high-Q microresonator assisted by a lightwave component analyzer (LCA). By scanning the modulation-sideband frequencies, LCA can determine the precise frequency separation of the microresonator resonance modes on the left and right sides of the probe light. Next, the dispersion parameters of all resonance modes in the high-Q microresonator can be obtained by varying the position of the probe light. The microresonator's dispersion parameters are also characterized using a fiber ring scheme, thereby verifying the accuracy of the LCA. The results from the two methods matched well, but the LCA method showed superior accuracy and required no additional reference frequency markers.

Electro-optic (EO) Mach-Zehnder modulators (MZMs) featuring high modulation efficiency and wide bandwidth are essential for large-capacity optical communication systems. To date, thin-film lithium niobate (TFLN) MZMs have emerged as a promising solution owing to the exceptional EO bandwidth and compactness, and thus significantly reduced capacitance. However, integrated TFLN MZMs are still several millimeters to centimeters in path length due to the limited modulation efficiency determined by the suboptimal confinement of the electric and optical fields. This limitation hinders large-scale integration for parallelization or multiplexing and prevents the economically efficient co-integration with compact electronics. Here, this challenge is overcome by merging sub-wavelength plasmonic slot waveguides with the TFLN platform to form a strong field confinement below the diffraction limit of optics, and enhance EO overlap and light-matter interactions. A record-high modulation efficiency of 0.070 V cm is demonstrated with an ultra-short length of 15 mu m. This plasmonic TFLN MZM exhibits a 3-dB EO bandwidth exceeding 110 GHz that allows for transmitting 110 Gbaud binary phase-shift keying signals with a bit error ratio of 2.5 x 10-5. This demonstrated plasmonic TFLN MZM provides a promising solution to future ultra-high-speed and large-scale photonic integrated systems for optical interconnections, optical computing, and optical sensing functions.

Precise control of the free spectral range (FSR) in high-repetition-rate (e.g., 100 GHz) optical frequency combs is critical for advanced applications but remains technically challenging. The frequency domain Talbot effect has emerged as a predominant mechanism for such spectral reconfiguration. Conventional Talbot-based methods face distinct limitations: electro-optic modulation is constrained by bandwidth, while cross-phase modulation demands complex pulse shaping. Furthermore, traditional four-wave mixing (FWM) schemes suffer from bulky footprints and instability due to their reliance on long fibers. Here, we demonstrate on-chip spectral densification by integrating a silicon nitride chirped waveguide Bragg grating (CWBG) with an FWM time lens. Replacing the kilometer-scale fibers used in standard setups, our CWBG generates the requisite large group delay within a centimeter-scale footprint. This compact chip-based dispersion module significantly reduces the long-fiber footprint and mitigates environmental instability and higher-order dispersion distortions. We experimentally compressed the FSR of a 100-GHz comb by integer factors (N = 2, 3, 4), thereby validating a robust, scalable platform for miniature spectral reconstruction in microwave photonics.

Spectral cloaking, by creating a spectral hole in a probe signal within which the spectrum of an obstacle signal can hide, is an important technology for encrypted communications and signal processing. Previous studies mainly rely on electro-optic modulations to realize spectral cloaking, which, however, suffer from inherent bandwidth limitations. By constructing a nonlinear four-wave mixing (FWM) time lens, we achieve the spectral Talbot effect and apply it to realize broadband spectral cloaking. We analyze the conditions to realize integer and fractional spectral Talbot effect, whereby arbitrary scaling of the free spectral range (FSR) of an input frequency comb can be achieved. By further cascading two FWM time lenses with reversible dispersions, we achieve FSR reconstruction for the input signal via spectral multiplication and division, thus creating a broadband spectral cloak up to 40 GHz in between. Such a cloak can hide the spectral information of an obstacle signal from being probed by the signal light, thus realizing invisible functionality. We establish an all-optical approach for realizing advanced spectral cloaking through FSR control, paving also promising avenues toward high-security encryption and antijamming optical communications.

Traditional wavelength division multiplexing systems rely on bulky laser arrays that exhibit limited coherence and pronounced frequency drift. In contrast, dissipative Kerr soliton microcombs represent an advanced class of multiwavelength laser sources for optical fiber communication, capable of generating comb lines with outstanding frequency and phase stability. Their high coherence enables terabit-per-second optical transmission within a single integrated photonic chip. However, high-capacity communication systems pose substantial challenges for conventional wavelength division multiplexing signal detection and optical performance monitoring, mainly due to bandwidth limitations and difficulties in signal synchronization. In this work, we demonstrate a data transmission rate of 2.4 Tbit/s using 30 wavelength channels sourced from a stabilized dissipative Kerr soliton microcomb. By leveraging a proposed complex-field optical oscilloscope, we synchronously capture and analyze 30 x 80 Gbit/s quadrature phase-shift keying signals, enabling precise characterization of carrier frequency drifts in each channel. These findings underscore the potential of dissipative Kerr soliton microcombs, combined with advanced optical oscilloscopes, as a promising platform for next-generation terabit-scale optical transceivers.

We designed and fabricated an integrated dispersion chipset that engages a four wave mixing (FWM)-type time lens to demonstrate free spectral range (FSR) manipulation of a 100 GHz signal based on the Spectral Talbot effect.

High-speed and energy-efficient data center interconnects yearn for the high-performance optical interconnects, which are powered by the dense-wavelength-division-multiplexing (DWDM) optical transmitters with integrated multi-channel silicon modulators. However, the contradiction for minimizing the crosstalk while maximizing the transmission capacity remains a critical obstacle for optical transmitters. Here, we propose and demonstrate a 20-channel DWDM optical transmitter with a compact channel spacing of 100 GHz, being enabled by the Kerr microcomb source and micro-ring modulators (MRMs) array. By introducing channel de-interleaving architecture and the large-bandwidth MRM with high modulation efficiency, spectral aliasing and crosstalk are effectively mitigated, resulting in a single-channel data rate of 128 Gb/s and an ultra-high total capacity of 20 x 128 Gb/s, as well as a high spectral efficiency of 1.28 bps/Hz. Experimental results show open eye diagrams of high-speed four-level pulse amplitude signals and a low power consumption of 5.85 pJ/bit is achieved. This work underscores the potential of Kerr comb source and MRMs array for advanced optical transmitters, contributing to the development of high-capacity and low-power optical interconnects.

An optical phased array (OPA) featuring all-solid-state beam steering is a promising component for light detection and ranging (LiDAR). There exists an increasing demand for panoramic perception and rapid target recognition in intricate LiDAR applications, such as security systems and self-driving vehicles. However, the majority of existing OPA approaches suffer from limitations in field of view (FOV) and do not explore parallel scanning, thus restricting their potential utility. Here, we combine a two-dimensional (2D) grating with an FOV-synthetization concept to design a silicon-based top-facing OPA for realizing a wide cone-shaped 360 degrees FOV. By utilizing four OPA units sharing the 2D grating as a single emitter, four laser beams are simultaneously emitted upwards and manipulated to scan distinct regions, demonstrating seamless beam steering within the lateral 360 degrees range. Furthermore, a frequency-modulated dissipative Kerr-soliton (DKS) microcomb is applied to the proposed multi-beam OPA, exhibiting its capability in large-scale parallel multi-target coherent detection. The comb lines are spatially dispersed with a 2D grating and separately measure distances and velocities in parallel, significantly enhancing the parallelism. The results showcase a ranging precision of 1 cm and velocimetry errors of less than 0.5 cm/s. This approach provides an alternative solution for LiDAR with an ultra-wide FOV and massively parallel multi-target detection capability. (c) 2025 Chinese Laser Press

Hyperspectral imaging systems are valuable for various applications, but conventional spectral imaging systems often rely on time-consuming scanning mechanisms, hindering real-time imaging capabilities. Recently, diffractive spectral snapshot imaging (DSSI) systems have enabled compact and lightweight approach to capture spectral information from dynamic scenes. However, dedicated research on reconstructing DSSI-encoded images is still limited. Existing methods often adopt models originally designed for recovering hyperspectral images from clean RGB inputs, which are not fully suitable for DSSI systems. In this paper, we analyze the characteristics of DSSI systems and highlight the need for modeling long-range dependencies. By leveraging a novel state space model, we can capture these dependencies with relatively low computational cost. We further introduce a local-enhanced branch to the original vision state space module and build a local-enhanced long-range dependency block. Additionally, we propose a data selection strategy to improve optimization stability and reconstruction performance. Our approach achieves state-of-the-art performance on benchmark datasets and demonstrates superior reconstruction quality in real-world captured data.

Continuous real-time analysis of the microwave spectrum is crucial for observing and analyzing high-speed random events and short-duration transient events. However, most current schemes analyze the spectrum in real-time with gaps, which inevitably leads to the loss of some critical information. A gap-free real-time microwave spectrum analyzer based on temporal convolution is demonstrated experimentally. By leveraging the temporal overlapping of stretched pulses, the analyzer achieves a high frame rate of 233 MHz, a frequency resolution of approximate to 500 MHz, an instantaneous bandwidth (dual sidebands) of nearly 130 GHz, a 100% signal capture ratio, and a measurement accuracy better than 20 MHz. Owing to the exemplary system performance, the real-time dynamic frequency identification for different types of microwave signals covering the S-band to Q-band is demonstrated, and the frequency can be accurately identified at any given time. Furthermore, the real-time capturing of transients is also demonstrated continuously. The high-performance analyzer can open a new horizon for real-time analysis and processing of high-speed time-domain waveforms in communication, imaging, and sensing applications.

Laser-based light detection and ranging technology, a vital tool for fast long-range distance measurement, plays an essential role across both scientific and industrial fields. The conventional dual-comb ranging method is a critical player in this field with high precision. However, the Nyquist sampling theorem results in a trade-off between the measurement speed and precision, and the non-ambiguity range (NAR) is also limited by the comb cycle, which hinders the further advancement of the technology. To address these issues, dual-chirped-comb interferometry has emerged as an innovative technique that eliminates the measurement speed limitation and extends the NAR for real-time ranging. With the utilization of dual-comb and dispersive time-stretch techniques (or dispersive Fourier transform), the inherent constraint imposed by the Nyquist sampling theorem is considerably alleviated, facilitating a transient distance measurement. This paper introduces the principle of dual-chirped-comb interferometry and discusses the critical factors for achieving absolute distance measurement. The advancement in speed, in comparison to the conventional dual-comb ranging method, has also been emphasized. In addition, some remarkable works and results are presented to visualize the system’s performance. Finally, this paper provides a perspective on potential future improvements and applications, such as in acoustic sensing, and explores the outlook for this emerging technology in the conclusion part.

We demonstrate an on-chip circulator-free narrow-bandwidth, large-dispersion delay line based on 20.11-cm-long Archimedean spiral cladding-modulated chirped Bragg gratings on a silicon nitride platform. The device achieves a 558-ps/nm dispersion over a bandwidth of 2.8 nm.