An integrated compact light engine configured in a on-board in-package optics assembly. The compact light engine includes a single substrate to integrate multiple optical-electrical modules. Each optical-electrical module includes an integrated optical transceiver based on silicon-photonics platform, in which a transmit path configured to output four light signals centered at four CWDM wavelengths and from four laser devices and to modulate the four light signals respectively by four modulators driven by a driver chip and to deliver a multiplexed transmission light. A receive path includes a photodetector to detect four input signals demultiplexed from an incoming light and a trans-impedance amplifier chip to process electrical signals converted from the four input signals detected. A multi-channel light engine is formed by co-integrating or co-mounting a switch device with multiple compact light engines on a common substrate member to provide up to 51.2 Tbit/s total capacity of data communication with median-or-short-reach electrical interconnect.