Light turning mirrors for hybrid integration of optical waveguides in SiON technology and CMOS based photo-detectors

An efficient connection of integrated optical components and photo-detectors (PDs) is very important to realize small size and high functionality optoelectronic devices. A number of techniques have been reported to provide such a connection. One of these uses a focusing grating coupler on top of a waveguide (WG) to focus the light to the PD above the WG [1]. However, high volume production of such devices is not possible because no mask can be used to define the grating, owing to its relatively small period. Another technique uses a focused ion beam to mill total internal reflection (TIR) mirrors, but this technique is also not suitable for high volume production [2]. The third technique is based on a metal mirror, at which the desired mirror angle is fabricated by using a superficial layer in the wet etching process [3]. The efficiency of the mirrors is very high, but the thermal budget of the fabrication process is low because the melting temperature of metal layer used in the mirror is low.