Monolithic InP Receiver Chip With a Variable Optical Attenuator for Colorless WDM Detection

We demonstrate a monolithically integrated quadrature coherent receiver photonic integrated circuit (PIC) on an InP substrate. The PIC comprises a 90° optical hybrid, a variable optical attenuator (VOA), and four RF photodetectors. With a dynamic range of 25 dB, the VOA enables the usage of the receiver PIC for colorless WDM detection.