Fabrication of semiconductor optical switch module using laser welding technique

The 4×4, 1×2, and 1×4 semiconductor optic-switch modules for 1550 nm optical communication systems were fabricated by using the laser welding technique based on the 30-pin butterfly package. For better coupling efficiency between a switch chip and an optical fiber, tapered fibers of 10-15 μm lens radius were used to provide the coupling efficiency up to 60%. The lens to lens distance of the assembled tapered fiber array was controlled within ±1.0 μm. A laser hammering technique was introduced to adjust the radial shift, which was critical to obtain comparable optical coupling efficiencies from all the channels at the same time. The fabricated optical switch modules showed good thermal stability, with less than 5% degradation after a 200 thermal cycling. The transmission characteristics of the 4×4 switch module showed good sensitivities, providing error free transmissions below -30 dBm for all the switching paths. The dynamic ranges for the 4×4 and 1×2 switch modules were about 8 dB for a 3 dB penalty and about 17 dB for a 2 dB penalty, respectively.