Patent ID: 8081376

Claim:
A light source apparatus comprising: a front-stage optical amplifier waveguide amplifying light to be amplified by transmitting first pumping light and the light to be amplified, the first pumping light having the same transverse mode as the light to be amplified; a rear-stage optical amplifier waveguide amplifying the light to be amplified from said front-stage optical waveguide by transmitting a second pumping light and the light to be amplified, the second pumping light having a different transverse mode from the light to be amplified; a pumping light source outputting the first pumping light in a single transverse mode, the first pumping light being supplied to the front-stage optical amplifier waveguide; an optical multiplexer multiplexing the first pumping light outputted from said pumping light source and the light to be amplified, and introducing the multiplexed light into said front-stage optical amplifier waveguide; an optical output waveguide being a transmission medium optically connected to an output end of said rear-stage optical amplifier waveguide, said optical output waveguide constituting a part of a propagation path of the light to be amplified that has been emitted from said rear-stage optical amplifier waveguide; and an optical component provided on an optical path between said pumping light source and said rear-stage optical amplifier waveguide, said optical component having an insertion loss spectrum that attenuates stimulated Raman scattered light generated in said optical output waveguide but allows the first pumping light or the light to be amplified to transmit therethrough.