Micromachining in silicon is a well established technique for manufacturing sensors and actuators. Another field is fiber
alignment components such as V-grooves and reflecting mirrors.
This work is aimed towards a batch fabricated opto coupler with the use of both V-grooves and perpendicular inflecting
mirrors on the same silicon wafer, with a maximum utilization of the single crystalline lattice structure. Since both the
(1 1 1) and (100)-etchstop planes are given by the crystal lattice structure, it is possible to obtain a well defmed 45 degree
angle between the [1 10] and -directions.
The main function of the (2x2) coupler is that a perpendicular wall has a height that covers half the fiber core. The result
is that half of the incoming light beam passes over the wall and the other half is reflected.
There will obviously be some geometrical limitations for the distance between the fibers, which introduces optical loss
that must be considered.
The measured excess loss is 4dB above the theoretical limit.