Design and fabrication of silicon optical bench for passive-aligned optical packaging

This paper presents the design and fabrication of silicon optical benches f or passive-aligned packaging of optical transmitter and receiver submodules . The optical submodules comprise of laser diode, photodiode, and optical f iber. New features in this design and fabrication are; i) performing the mo st critical processing steps such as under bump metal (UBM) and alignment f iducials prior to V-groove etching, ii) taking the advantage of the lithogr aphic self alignment between the alignment guides. These fabrication method s are accomplished by establishing the protection technique of UBM patterns in the KOH solution. In the results, the silicon optical benches having mi salignment tolerances of about +/-0.5 mu m for both lateral and vertical di rections are achieved. The optical coupling performances accomplished by th e use of silicon optical bench and index alignment method are summarized as an excess coupling loss of 1.79+/-1.55 and a responsivity of 0.81+/-0.05 A /W, respectively for a laser-to-fiber and a photodiode-to-fiber coupling.