Optical and Electrical Characterization of a Compact Universal Photonic Engine

Abstract

We present the inaugural wafer-level characterization results of the TSMC Compact Universal Photonic Engine (COUPE) based on a grating coupler (GC) geometry. The optical path within the COUPE stack is meticulously designed to minimize impacts on optical properties, such as insertion loss and wavelength shift. To achieve this, features including an embedded micro-lens array, a backside metal reflector, and anti-reflective coating (ARC) layers have been developed. Following process optimization, the optical insertion loss of a GC measured on COUPE consistently remains below 1.2 dB, matching that measured on the photonics integrated circuit (PIC) wafer. This indicates that there is essentially no additional loss from transitioning the system from PIC to COUPE. The 1 dB bandwidth is approximately 25 nm, which is about 5 nm larger than that at the PIC wafer level. The central wavelength across the 300 mm wafer is tightly controlled within ± 1.7 nm of the incident wavelength in the O-band region. Electrical and reliability results are also reported. Our findings demonstrate that COUPE holds significant potential for use in pluggable transceivers or copackaged optics (CPO) for advanced networking and artificial intelligence (AI) applications.