Patent ID: 7373048

Claim:
A polarization insensitive semiconductor optical amplifier (SOA), comprising an active waveguide, a passive waveguide, and a taper coupler for coupling optical signal energy from said passive waveguide into said active waveguide, said taper coupler having width W in a lateral x direction transverse to a z direction of a main axis of propagation of said SOA, said width W varying relative to position in said z direction, wherein a rate of variation (dw/dz) of said width W relative to the position in said z direction is in proportion to the minimum value of 1/C TE 01 (z) and 1/C TM 01 (z), where C TE 01 (z) represents the coupling coefficient between a fundamental mode and a first order mode for the transverse electric polarization at a position along the main axis, and C TM 01 (z) represents the coupling coefficient between a fundamental mode and a first order mode for the transverse magnetic polarization at that position.