Tunable multi-mode laser

摘要

A widely tunable multi-mode semiconductor laser 100 has two electrically active sections 110, 112, being an optical gain section 110 and a tunable distributed Bragg reflector 112 adapted to reflect at a plurality of wavelengths. The gain section 110 is bounded by the tunable distributed Bragg reflector and a broadband facet reflector. The tunable distributed Bragg reflector 112 may be a linearly chirped grating which comprises a plurality of discrete segments 112A-112 H capable of being selectively tuned. The reflection spectra of one or more segments of the tunable distributed Bragg reflector can be tuned lower in wavelength to reflect with the reflection spectrum of a further segment of the tunable distributed Bragg reflector to provide a wavelength range of enhanced reflectivity. An optical transmitter may comprise the widely tunable multi-mode semiconductor laser as a Raman amplification pump laser.