Promising intracavity mode-locking device: A strained GaInAs/AlInAs saturable Bragg reflector grown by molecular-beam epitaxy

A strained GaInAs/AlInAs saturable Bragg reflector (SBR) was fabricated from layers grown by molecular-beam epitaxy. The device consisted of nominally 25 periods of GaAs/AlAs Bragg structures incorporating double GaInAs/AlInAs quantum wells latticed matched to InP. The SBR was measured to be more than 99.5% reflective from 1410 to 1525 nm. The structural parameters for the sample were obtained from high-resolution x-ray diffraction rocking curves. The quantum wells exhibited partially relaxed interfaces where the relaxation was characterized by misfit dislocations. The photoluminescence measurements showed a lack of well-defined band edges and exciton structure at room temperature. Luminescence peaks were obtained at liquid-helium temperature, corresponding to heavy-hole and light-hole related exciton levels. The fast recovery of the SBR nonlinear response was explained by the misfit dislocations, which act as nonradiative recombination centers. (C) 2000 American Institute of Physics. [S0003-6951(00)01407-8].