Efficient Optically-Pumped Semiconductor Optical Amplifier in a Coupled-Waveguide Configuration: A Novel Proposal

Abstract

We propose an efficient scheme of optical pumping and a compact design of an optically-pumped semiconductor optical amplifier (OP-SOA), with gain characteristics which are qualitatively similar to that of conventional (electrically-pumped) SOA. The optical pump is coupled into the ‘active waveguide’ from an adjacent channel waveguide, called ‘pump waveguide’; by suitably tailoring the coupling between the two waveguides, selective transfer of pump power all along the active waveguide can be achieved. We show that optical pumping through the coupled-waveguide configuration is efficient over the existing schemes of optical pumping in semiconductors. The optical pump can be coupled into the pump waveguide through a separate fiber-pigtail, just as the signal is coupled to the active waveguide in commercially available SOA. Thus, the OP-SOA would be a stand-alone 3-port integrated optical device, without any electrical connections. The proposed scheme enables optical-to-optical gain control, in place of the current-controlled gain in conventional SOA. Performance characteristics of the OP-SOA are simulated for an InGaAsP/InP heterostructure device using a well-established model. It is found that for an input optical pump power of 25 dBm at the wavelength of 1310 nm, a small signal gain >30 dB is achieved at the wavelength of 1550 nm.