SEMICONDUCTOR LASER TYPE OPTICAL AMPLIFYING ELEMENT

摘要

PROBLEM TO BE SOLVED: To easily form a semiconductor laser type optical amplifying element, wherein gain characteristics is hard to fluctuate even when a polarization state of input signal light fluctuates. SOLUTION: A taper waveguide channel 103a is provided at both ends in waveguide direction of an active layer 103 on a clad layer 102, while connected to an end part of the active layer 103. The taper waveguide channel 103a comprises, for example, an InGaAsP of band gap wavelength 1.3μm. The taper waveguide channel 103a is so formed as to be thinner in film thickness as going away from a joint part to the active layer 103.