Passive nonlinear technique to mode-lock, stabilize and ensure bi-directionality in a solid state ring laser

Summary form only given. We present a solution that ensures bi-directional cw mode-locked (CWML) operation, combining saturable absorbers with an energy limiter. Multiple quantum wells (MQW) grown on bulk GaAs are inserted in the cavity between two f = 22.91 mm lenses. Bi-directional operation is preferred since the quantum well saturation energy in a standing wave is effectively 1/4 of that for a travelling wave. The two-photon-induced carriers in GaAs create a negative lens, leading to beam magnification. The slit at that position acts as an energy limiter, suppressing Q-switched operation, provided the GaAs is properly positioned.