Abstract

Resonant passive mode-locking (RPM) is a new technique for picosecond to femtosecond pulse generation in solid-state lasers using a quantum well reflector in a coupled cavity. This approach has several key features for generating short pulses with a compact and reliable laser, such as one mode-locker works for any repetition rate; the RPM does not require active cavity length control, and the QW reflector is a bulk device requiring no critical alignment. The RPM was first demonstrated with a Ti:sapphire laser.¹,² Femtosecond pulses were achieved in a dispersion-compensated Ti:sapphire laser where the quantum well reflector continuously started Kerr lens mode-locking.³ An RPM Nd:YLF laser was first demonstrated with a 1.06-µm InGaAs/GaAs light modulator.⁴ We present results using improved low-temperature grown material, which produced as short as 3.7 psec with good stability. Average output power was 370–450 mW at 250-MHz repetition rate with a pump power of 1.3 W from a cw Ti:sapphire laser. Spontaneous self-Q-switching is suppressed by using an aperture to insure TEM₀₀ spatial mode. The low temperature grown InGaAs/GaAs MQW device has two advantages: no surface striation which reduces its fixed loss and a short carrier lifetime which is necessary for high repetition rates.

© 1991 Optical Society of America