A compact and high-sensitivity Mach–Zehnder interferometer refractive index sensor is designed and fabricated on a standard 0.18 µm silicon-on-insulator process. The key is the design of a multi-slot subwavelength grating (MSGG) waveguide in the sensing arm, which synergistically combines the strong optical confinement of slot waveguides with the engineered dispersion of subwavelength gratings. By leveraging this MSSG structure, the device achieves a high experimental sensitivity of 462.4 nm/RIU for a sensing length of only 100 µm. The sensor’s compatibility with standard, low-cost CMOS fabrication positions it as a promising and scalable solution for a variety of integrated optical sensing applications.

Resonant integrated optical gyroscopes (RIOGs) could integrate multiple devices onto a single chip, further reducing the size and weight of the gyroscope and opening it up to a broader spectrum of applications. This paper conducts in-depth research on resonant optical gyroscopes. A silicon on insulator (SOI) resonator ring with a Q value of 4.65×10⁶ was designed based on the Hermite curve. A resonant micro-optical gyroscope (RMOG) was achieved using the resonator ring, traditional phase modulators, and detectors. The results show that the bias instability of the RMOG can reach 0.004°/s, and the gyroscope has the ability to detect angular velocities ranging from −600°/s to +600°/s. Furthermore, a RIOG was demonstrated by designing PIN modulators, detectors and a ring resonator on a single chip, significantly reducing the system floor space to 25 mm², and the bias instability testing is 0.06°/s.

Mode converters play a critical role in mode-division multiplexing (MDM) systems. This paper proposed and demonstrated a design method of high conversion efficiency (CE) and broadband mode converters based on cubic spline interpolation curves. The cubic spline interpolation method provides great flexibility in defining the boundaries of irregularly shaped waveguide curves. This design effectively improves the mode conversion efficiency and can be applied to different mode orders and multimode waveguide widths. For the TE0–TE1 converters, we designed different multimode waveguide widths (1 µm and 1.1 µm) to demonstrate the flexibility of the design approach. At 1550 nm, the conversion efficiencies of the TE0–TE1 converters and TE0–TE2 converters are −0.026dB (99.4%) and −0.039dB (99.1%), respectively, according to the theoretical results. The mode converters were manufactured using a standard process provided by the foundry, and the measured conversion efficiency for all devices was above −0.419dB (90.8%) in the wavelength range of 1530–1565 nm.

The noise of a resonant integrated optical gyroscope (RIOG) remains a critical bottleneck for ultra-high precision applications. This paper presents a cascaded "physics-prior and data-driven" denoising framework: fast Fourier transform (FFT) comb filtering was first employed to suppress discrete spectral lines at 0 Hz, 50 Hz, and harmonics; a lightweight convolutional neural network (CNN)-long short-term memory (LSTM) hybrid network then deeply extracted spatiotemporal noise characteristics. The network architecture is composed of: 64-point sliding windows (step=2), two 1D convolutional layers (16×8 and 32×4) for local features, a 32-unit LSTM for long-term dependencies, and a linear output layer for noise regression. Experiments on 1 kHz-sampled, 2000000 points field data show that the proposed method reduces angular random walk (ARW) to 0.28 ^∘ /h and bias instability to 2.52 °/h. These results show an approximately 50% reduction in both ARW and bias instability compared to our previously reported method, which marks a significant advance in gyroscopic noise suppression. This study demonstrates the strong generalization of "frequency-domain physical constraints and spatiotemporal deep learning" for high-performance gyroscope signal processing.

We designed a narrow-linewidth external-cavity hybrid laser leveraging a silicon-on-insulator triple Euler gradient resonant ring. The laser’s outer cavity incorporates a compact, high-Q resonant ring with low loss. The straight waveguide part of the resonant ring adopts a width of 1.6 μm to ensure low loss transmission. The curved section is designed as an Euler gradient curved waveguide, which is beneficial for low loss and stable single-mode transmission. The design features an effective bending radius of only 26.35 μm, which significantly improves the compactness of the resonant ring and, in turn, reduces the overall footprint of the outer cavity chip. To bolster the laser power and cater to the varying shapes of semiconductor optical amplifier (SOA) spots, we designed a multi-tip edge coupler. Theoretical analysis indicates that this edge coupler can achieve an optical coupling efficiency of 85%. It also reveals that the edge coupler provides 3 dB vertical and horizontal alignment tolerances of 0.76 μm and 2.4 μm, respectively, for a spot with a beam waist radius of 1.98 μm × 0.99 μm. The outer cavity, designed with an Euler gradient micro-ring, can achieve a side-mode suppression ratio (SMSR) of 30 dB within a tuning range of 100 nm, with a round-trip loss of the entire cavity at 1.12 dB, and an expected theoretical laser linewidth of 300 Hz.

We report a dispersion-controlled Yb-doped fiber chirped pulse amplification (CPA) system incorporating a tunable chirped fiber Bragg grating (CFBG) stretcher and a single-grating transmission compressor for dynamic compensation of power-dependent nonlinear effect. During the pulse amplification, the CFBG introduces adjustable third-order dispersion (TOD). By tuning the initial TOD provided by CFBG from −0.1965 ps³ at 2.37 W to −0.1791 ps³ at 9.65 W, residual TOD is efficiently compensated with the power-dependent nonlinear effect. As a result, by optimizing the dispersion balance at each output power, nearly constant femtosecond pulses with a duration of 250 fs are obtained over the entire power range, confirming effective control of nonlinear and dispersive effects in the amplification. The high-quality 1030 nm pulses enable efficient second-harmonic generation (SHG) in a type-I BBO crystal, producing 3.56 W femtosecond output at around 515 nm with a pulse duration of 190 fs, close to the Fourier transform limit. These results demonstrate a robust approach to generating high-power and temporal coherent ultrafast pulses suitable for precision micromachining and two-photon polymerization.