High-Speed and High-Responsivity Asymmetric Waveguide Photodiode with Low Optical Back-Reflection

We numerically demonstrate an asymmetric corner-reflector uni-traveling-carrier waveguide photodiode (UTC-WGPD) that simultaneously suppresses optical back-reflection and breaks the bandwidth-responsivity trade-off. Off-center beam coupling introduces geometric asymmetry to eliminate retroreflection while maintaining efficient light trapping. 3D optoelectronic simulations reveal that at 1550 nm, a 15-μm^2 device exhibits a 275-GHz 3-dB bandwidth, 0.68-A/W responsivity (54.5% quantum efficiency), and -29-dB back-reflection, achieving a 150-GHz bandwidth-efficiency product. This design offers a scalable, low-reflection detection scheme for sub-terahertz transceivers and dense photonic integration.