In this paper, we design and experimentally demonstrate an eight-channel cascaded Mach–Zehnder interferometer (MZI) based Local Area Network (LAN) Wavelength Division Multiplexing (WDM) (de)multiplexerwith channel spacing of 800 GHz on a silicon-on-insulator. By cascading a three-stage MZI, eight target wavelengths are (de)multiplexed. The length difference of the third-stage MZI delay arms is adjusted so that the output channels skip the guard band. In order to keep the central wavelength of each channel from shifting, we utilize a wide waveguide for the phase delay arm in MZI to achieve large fabrication tolerance, and the multi-mode interference (MMI) couplers as power splitters with weak dispersions. The measurement results of the fabricated device show the precise wavelength alignment over the whole working wavelength range.

Optical 3 dB power splitters are fundamental building blocks for advanced silicon photonic integrated circuits, with applications ranging from high-speed modulators to optical phased arrays and programmable photonic processors. However, 3 dB power splitters are commonly hampered by trade-offs in device dimensions, operation bandwidth, and fabrication technology. In this paper, we present a compact and ultra-broadband 3 dB power splitter based on segmented adiabatic tapered rib waveguides, with a length of 23.4 μm. The simulated splitter achieved an output transmission efficiency exceeding 48% over a large wavelength of 400 nm (1200–1600 nm). The power splitter was successfully fabricated on a commercial platform and exhibited excellent splitting ratios within 50 ± 3.8% and insertion losses below 0.38 dB over the range of 1260–1360 nm and 1525–1600 nm. Additionally, a high-speed Mach–Zehnder modulator based on the power splitter was built, demonstrating 40 Gbps NRZ signal modulations across both O-band and C-band. The proposed splitter and modulator are promising elements for large-scale and broadband integrated photonic systems.

Micro-racetrack resonators have become one of the key components for realizing signal processing, generation, and integration in microwave photonics, owing to their high Q factor, compact footprint, and tunability. However, most of the reported micro-racetrack resonators are confined to the single-mode regime. In this paper, we designed an ultra-compact multimode micro-racetrack resonator (MMRR) based on shape-optimized multimode waveguide bends (MWBs). Cubic spline curves were used to represent the MWB boundary and adjoint methods were utilized for inverse optimization, achieving an effective radius of 8 μm. Asymmetric directional couplers (ADCs) were designed to independently couple three modes into a multimode micro-racetrack, according to phase-matching conditions and transmission analysis. The MMRR was successfully fabricated on a commercial platform using a 193 nm dry lithography process. The device exhibited high loaded Q factors of 2.3 × 10⁵, 4.1 × 10⁴, and 2.9 × 10⁴, and large free spectral ranges (FSRs) of 5.4, 4.7, and 4.2 nm for ${\mathrm{TE}}_0$, ${\mathrm{TE}}_1$, and ${\mathrm{TE}}_2$ modes, with about a 19 × 55 μm² footprint.

Microring resonators have become one of the key components for realizing signal processing, generation, and integration in microwave photonics, owing to their high Q factor, compact footprint, and tunability. However, most of the reported microring resonators are confined to the single-mode regime. In this paper, we design an ultra-compact multimode microring resonator (MMRR) based on shape-optimized multimode waveguide bends (MWBs). Cubic spline curves are used to represent the MWB boundary and the adjoint methods are utilized for inverse optimization, achieving an effective radius of 8 μm. Asymmetric directional couplers (ADCs) are designed to independently couple three modes into multimode microring, according to phase-matching conditions and transmission analysis. The MMRR is successfully fabricated on a commercial platform using 193-nm dry lithography process. The device exhibits high loaded Q factors of 2.3 × 105, 4.1 × 104 and 2.9 × 104, and large free spectral ranges (FSRs) of 5.4, 4.7 and 4.2 nm for TE0, TE1 and TE2 modes, with about 19 × 55 μm² footprint.