A packaging technique for an optical 90°-hybrid balanced receiver using a planar lightwave circuit

A new technique has been developed for packaging an optical 90°-hybrid balanced receiver using a planar lightwave circuit (PLC) for the application to an optical homodyne detection system. This receiver consists of a silica-based PLC as an optical coupler, two polarization beam splitters (PBSs), two GRIN rod lenses to achieve perfect optical interconnections, two photoreceivers that each have a preamplifier, and twin p-i-n photodiodes (PIN-PDs). The photoreceivers are fabricated using microsolder bump bonding to eliminate parasitic elements in the interconnections between the preamplifiers and the PIN-PDs. An impedance-matched film carrier technique is used to achieve impedance-matched interconnections between the preamplifiers and the ceramic packages. Experiments showed that a receiver fabricated using this packaging technique has excellent performance: a broad-band frequency response of 14 GHz and, consequently, 10-Gb/s binary phase shift keying (BPSK) homodyne detection