A method for fabricating an optical multi-chip module (MCM) includes temporarily curing an underfill material on a chip including an optical device to prevent flow of the underfill material. The chip is flip-chip mounted on a waveguide module having a mirror for directing light to or from the chip, wherein the underfill material is disposed between the chip and the waveguide module. The underfill material is cured to adhere the chip to the waveguide module.