Efficient planar-integrated free-space optical interconnects fabricated by a combination of binary and analog lithography

Design, fabrication, and experimental testing of an integrated microoptical module for interconnection are reported. The systems integration is based on the concept of planar-integrated free-space optics. The module combines diffractive-reflective and refractive microoptics. The diffractive elements were fabricated by binary lithography and reactive ion etching. The refractive elements were made by analog lithography using a high-energy beam sensitive mask and replication in Ormocer. The fabricated module implemented a simple one-dimensional optical interconnect. Two versions were implemented for which insertion losses of approximately 8 and 4.5 dB were measured, respectively.