Coupled-Cavity Resonant Passive Modelocked (RPM) Nd:YLF Laser

Coupled cavity modelocking with a resonant nonlinearity in the coupled cavity is a new technique to passively modelock laser media with small gain saturation cross section and was introduced with a Ti:Sapphire laser [1,2]. As an extention of this work, we passively modelocked a cw pumped Nd:YLF laser with an InGaAs/GaAs strained layer MQW [3] resonant nonlinearity in the coupled cavity and generated 4 ps pulses at a wavelength of 1.047 µm with 390 mW average output power at a 250 MHz repetition rate, corresponding to a 1.6 nJ pulse energy. The RPM Nd:YLF laser consists of a linear folded, astigmatically compensated cw Nd:YLF cavity with a 3% coupler to an external low-Q cavity with a nonlinear InGaAs/GaAs quantum well end reflector. The overall tunable output coupler is in the coupled cavity and is typically ≈ 50%. The Nd:YLF rod is cw end- pumped with only 1.5 W at 798 nm from a Ti:Sapphire laser. RPM does not require active cavity length control for stable modelocked pulse trains [4], Diode pumping and higher repetition rates should deliver a practical high power high repetition source for photonic switching applications.