GaInNAs SESAMs passively mode-locking 1.3-μm solid-state lasers

Abstract

A GaInNAs semiconductor saturable absorber mirror (SESAM) is demonstrated that is able to passively mode-lock a 1.3-μm Nd:YLF laser. The mirror was grown by molecular beam epitaxy and consists mainly of a GaInNAs single quantum well on an AlAs/GaAs distributed Bragg reflector. Two designs were grown: resonant and antiresonant. The first favoured optical characterisation, while the second one was more fitted to self-start passive mode-locking in the laser. Rapid thermal annealing was used to tune this wavelength closer to the desired laser wavelength of 1314 nm. Nonlinear characterisation of both designs allowed calculation of the saturation fluence of a 10-nm GaInNAs QW with photoluminescence around 1330 nm independently of design. It was measured to be 3.5±0.5 μJ/cm2. The incorporation of about 2% of N in In0.36Ga0.64As red-shifted the as-grown photoluminescence to about 1370 nm. The nonlinear optical characterisation of the antiresonant SESAM showed low saturation fluence (11.2 μJ/cm2), low nonsaturable losses and a recovery time suitable for ps-pulse generation. With this SESAM we obtained clean self-starting mode-locking with 6.7-ps pulses at a repetition rate of 117 MHz and a maximum average output power of 580 mW.