Whispering gallery mode resonators (WGMRs) have proven their advantages in terms of sensitivity and precision in various sensing applications. However, when high precision is pursued, the WGMR demands a high-quality factor usually at the cost of its free spectral range (FSR) and corresponding measurement range. In this article, we propose a high-resolution and wide-range temperature sensor based on chip-scale WGMRs, which utilizes a Si3N4 ring resonator as the sensing element and a MgF2-based microcomb as a broadband frequency reference. By measuring the beatnote signal of the WGM and microcomb, the ultra-high resolution of 58 micro-Kelvin (μK) was obtained. To ensure high resolution and broad range simultaneously, we propose an ambiguity-resolving method based on the gradient of feedback voltage and combine it with a frequency-locking technique. In a proof-of-concept experiment, a wide measurement range of 45 K was demonstrated. Our soliton comb-assisted temperature measurement method offers high-resolution and wide-range capabilities, with promising advancements in various sensing applications.

片上超表面是将超表面引入到集成光波导上以实现对导波的任意调制，它为导波与自由空间光波之间的转换提供了一个方便且通用的平台。尽管之前在片上全息方面已经做出了一些探索，但在扩展编码自由度和多路复用方面仍需突破。本文提出并实验验证了一种基于片上超表面的多路复用全息显示器件。通过迂回相位和几何相位的融合,使片上超表面将导波以圆偏光的形式耦合到自由空间中，以打破此前片上超表面沿传播方向上相位简并的局限性，进一步扩展了编码自由度。同时使用模拟退火相位优化算法和多路复用技术，实现了可独立编码的四通道远场全息显示复用。本文的设计方法以片上超表面的多功能集成，为具有高信息存储容量的集成光通信提供了一种新的途径。

具有高品质因子（Q 值）的光学谐振腔能够长时间将光束缚在较小的模式体积内，极大地增强了光与物质的相互作用，成为集成光学器件中具有重大潜力的重要组成部分。聚焦于目前广泛应用于集成非线性光学领域的氮化硅材料平台，为了解决大尺寸氮化硅微环腔由拼接误差、表面粗糙等因素导致的散射损耗较大的问题，进行了一系列的工艺改进以提高大尺寸氮化硅微环腔的品质因子。结果表明：通过薄膜再沉积工艺可以有效降低氮化硅波导的散射损耗，半径为560 μm的大尺寸氮化硅微环腔的本征Q值得到了平均26% 的提升。得益于提高的微腔Q 值，在氮化硅微环腔中实现了重复频率40 GHz 的光学频率梳。

The microresonator-based soliton microcomb has shown a promising future in many applications. In this work, we report the fabrication of high quality (Q) Si3N4 microring resonators for soliton microcomb generation. By developing the fabrication process with crack isolation trenches and annealing, we can deposit thick stoichiometric Si3N4 film of 800 nm without cracks in the central area. The highest intrinsic Q of the Si3N4 microring obtained in our experiments is about 6×106, corresponding to a propagation loss as low as 0.058 dBm/cm. With such a high Q film, we fabricate microrings with the anomalous dispersion and demonstrate the generation of soliton microcombs with 100 mW on-chip pump power, with an optical parametric oscillation threshold of only 13.4 mW. Our Si3N4 integrated chip provides an ideal platform for researches and applications of nonlinear photonics and integrated photonics.

Chaotic dynamics in optical microcavities, governed dominantly by manifolds, is of great importance for both fundamental studies and photonic applications. Here, we report the experimental observation of a stable manifold characterized by energy and momentum evolution in the nearly chaotic phase space of an asymmetric optical microcavity. By controlling the radius of a fiber coupler and the coupling azimuth of the cavity, corresponding to the momentum and position of the input light, the injected light can in principle excite the system from a desired position in phase space. It is found that once the input light approaches the stable manifold, the angular momentum of the light experiences a rapid increase, and the energy is confined in the cavity for a long time. Consequently, the distribution of the stable manifold is visualized by the output power and the coupling depth to high-Q modes extracted from the transmission spectra, which is consistent with theoretical predictions by the ray model. This work opens a new path to understand the chaotic dynamics and reconstruct the complex structure in phase space, providing a new paradigm of manipulating photons in wave chaos.

Dissipative Kerr solitons offer broadband coherent and low-noise frequency combs and stable temporal pulse trains, having shown great potential applications in spectroscopy, communications, and metrology. Breathing solitons are a particular kind of dissipative Kerr soliton in which the pulse duration and peak intensity show periodic oscillation. Here we have investigated the breathing dissipative Kerr solitons in silicon nitride (Si3N4) microrings, while the breathing period shows uncertainties of around megahertz (MHz) order in both simulation and experiments. This instability is the main obstacle for future applications. By applying a modulated signal to the pump laser, the breathing frequency can be injection locked to the modulation frequency and tuned over tens of MHz with frequency noise significantly suppressed. Our demonstration offers an alternative knob for the control of soliton dynamics in microresonators and paves a new avenue towards practical applications of breathing solitons.

The dissipative sensing based on a self-interference microring resonator composed of a microring resonator and a U-shaped feedback waveguide is demonstrated experimentally. Instead of a frequency shift induced by the phase shift of the waveguide or the microcavity, the dissipative sensing converts the phase shift to the effective external coupling rate, which leads to the change of linewidth of the optical resonance and the extinction ratio in the transmission spectrum. In our experiment, the power dissipated from a microheater on the feedback waveguide is detected by the dissipative sensing mechanism, and the sensitivity of our device can achieve 0.22 dB/mW. This dissipative sensing mechanism provides another promising candidate for microcavity sensing applications.