Chip-based soliton frequency microcombs combine compact size, broad bandwidth, and high coherence, presenting a promising solution for integrated optical telecommunications, precision sensing, and spectroscopy. Recent progress in ferroelectric thin films, particularly thin-film lithium niobate (LiNbO3) and thin-film lithium tantalate (LiTaO3), has significantly advanced electro-optic (EO) modulation and soliton microcombs generation, leveraging their strong third-order nonlinearity and high Pockels coefficients. However, achieving soliton frequency combs in X-cut ferroelectric materials remains challenging due to the competing effects of thermo-optic and photorefractive phenomena. These issues hinder the simultaneous realization of soliton generation and high-speed EO modulation. Here, following the thermal-regulated carrier behavior and auxiliary-laser-assisted approach, we propose a convenient mechanism to suppress both photorefractive and thermal dragging effects at once, and implement a facile method for soliton formation and its long-term stabilization in integrated X-cut LiTaO3 microresonators for the first time, to the best of our knowledge. The resulting mode-locked states exhibit robust stability against perturbations, enabling new pathways for fully integrated photonic circuits that combine Kerr nonlinearity with high-speed EO functionality.

This paper presents the design, fabrication, and characterization of a high-performance heterogeneous silicon on insulator (SOI)/thin film lithium niobate (TFLN) electro-optical modulator based on wafer-scale direct bonding followed by ion-cut technology. The SOI wafer has been processed by an 8 inch standard fabrication line and cut into 6 inch for direct bonding with TFLN. The hybrid SOI/LN electro-optical modulator operated at the wavelength of 1.55 μm is composed of couplers on the Si layer and a Mach–Zehnder interferometer (MZI) structure on the LN layer. The fabricated device exhibits a stable value of the product of half-wave voltage and length (VπL) of around 2.9V·cm. It shows a good low-frequency electro-optic response flatness and supports 96 Gbit/s data transmission for the NRZ format and 192 Gbit/s data transmission for the PAM-4 format.

The 4H-silicon carbide on insulator (4H-SiCOI) has recently emerged as an attractive material platform for integrated photonics due to its excellent quantum and nonlinear optical properties. Here, we experimentally realize one-dimensional photonic crystal nanobeam cavities on the ion-cutting 4H-SiCOI platform. The cavities exhibit quality factors up to 6.1×103 and mode volumes down to 0.63 × (λ/n)³ in the visible and near-infrared wavelength range. Moreover, by changing the excitation laser power, the fundamental transverse-electric mode can be dynamically tuned by 0.6 nm with a tuning rate of 33.5 pm/mW. The demonstrated devices offer the promise of an appealing microcavity system for interfacing the optically addressable spin defects in 4H-SiC.

Generally, a superconducting nanowire single-photon detector (SNSPD) is composed of wires with a typical width of ∼100nm. Recent studies have found that superconducting strips with a micrometer-scale width can also detect single photons. Compared with the SNSPD covering the same area, the superconducting microstrip single-photon detector (SMSPD) has smaller kinetic inductance, higher working current, and lower requirements in fabrication accuracy, providing potential applications in the development of ultralarge active area detectors. However, the study of SMSPD is still in its infancy, and the realization of its high-performance and practical use remains an open question. This study demonstrates a NbN SMSPD with a nearly saturated system detection efficiency (SDE) of ∼92.2% at a dark count rate of ∼200cps, a polarization sensitivity of ∼1.03, and a minimum timing jitter of ∼48ps at the telecom wavelength of 1550 nm when coupled with a single-mode fiber and operated at 0.84 K. Furthermore, the detector’s SDE is over 70% when operated at a 2.1 K closed-cycle cryocooler.