Xin Tu

Compact PSR Based on an Asymmetric Bi-level Lateral Taper in an Adiabatic Directional Coupler

We propose a compact silicon-on-insulator polarization splitter-rotator (PSR). The PSR consists of an asymmetric bilevel lateral taper in an adiabatic directional coupler and convert TM₀ mode to TE₀ mode directly without changing the input TE₀ mode. Compared to the previously reported PSR based on TM₀ -TE₁ polarization rotator connected to a TE₁-TE₀ spatial mode order convertor in series, the proposed PSR has a one-step mode conversion, and is inherently more compact. Beside, since the conversion is fully adiabatic, it preserves the benefits of large fabrication tolerance and operation bandwidth. The simulation results show that the TM₀-TE₀ polarization conversion loss is less than 0.5 dB from 1500 to 1700 nm and even less than 0.2 dB over the whole C-band. The TE₀ -TE₀ insertion loss is less than 0.01 dB from 1450 to 1750 nm. The polarization crosstalk is below -35 dB within 300-nm bandwidth.

Low Polarization-Dependent-Loss Silicon Photonic Trident Edge Coupler Fabricated by 248 nm Optical Lithography

Trident edge couplers were fabricated using optical lithography. TE and TM coupling loss with lensed fiber were improved by 0.2 dB and 0.3 dB compared to a single-taper coupler. PDL was improved by 0.1 dB.

Silicon Photonic Switch Subsystem With 900 Monolithically Integrated Calibration Photodiodes and 64-Fiber Package

Monolithic germanium photodiodes on every cell calibrate a 32×32 silicon photonic switch of 448 Mach-Zehnders in 10 minutes. 64 fibers permanently attached through a waveguide concentrator in a wire-bonded BGA achieve 2.9dB C-band TE fiber-to-die.

2×2 multimode interference coupler with low loss using 248 nm photolithography

We demonstrate a 2×2 multimode interference coupler in 220 nm silicon photonics, with 3.8 μm by 152 μm footprint. Loss is ≤0.15±0.01 dB for 1530-1565 nm, across the 200 mm wafer using 248 nm lithography. This is the lowest loss reported for sub-micron silicon 2×2 MMI.

Compact low-loss adiabatic bends in silicon shallow-etched waveguides

We report an adiabatic bend based on silicon shallow-etched waveguide using a sine-circle-sine design. The loss per 180° turn is 0.05 dB for 5 μm bend and 0.008 dB 10 μm bend for TE polarization, which are significantly lower than that of a circular bend.