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

• Published in: Optics express 2013-10, Vol.21 (20), p.24375-24384
• Main Authors: Civitci, F, Sengo, G, Driessen, A, Pollnau, M, Annema, A J, Hoekstra, H J W M
• Format: Article
• Language: English
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.21.024375

For hybrid integration of an optical chip with an electronic chip containing photo-diodes and processing electronics, light must be coupled from the optical to the electronic chip. This paper presents a method to fabricate quasi-total-internal-reflecting mirrors on an optical chip, placed at an angle of 45° with the chip surface, that enable 90° out-of-plane light coupling between flip-chip bonded chips. The fabrication method utilizes a metal-free, parallel process and is fully compatible with conventional fabrication of optical chips. The mirrors are created using anisotropic etching of 45° facets in a Si substrate, followed by fabrication of the optical structures. After removal of the mirror-defining Si structures by isotropic etching, the obtained interfaces between optical structure and air direct the output from optical waveguides to out-of-plane photo-detectors on the electronic chip, which is aimed to be flip-chip mounted on the optical chip. For transverse-electric (transverse-magnetic) polarization simulations predict a functional loss of 7% (15%), while 7% (18%) is measured.