A Titanium-doped-sapphire laser source with tunable frequency, single-mode emission, and adjustable pulse duration

We present a laser source with several desirable characteristics, such as tunable wavelength in the near infrared, single-longitudinal-mode emission and variable pulse temporal duration in the nanosecond regime. The laser is based on an injection-seeded Titanium-doped-sapphire ring cavity. Our experiments show how the pulse duration can be varied in a controllable fashion either by changing the cavity length or by changing the pump energy. We present a theoretical model which successfully reproduces the experimental results by treating the operation of this type of laser as a gain-switching technique. As far as the stabilization of the laser cavity, we also present a novel solution involving the use of an avalanche photodiode.