Dual-wavelength oscillation in an electronically tuned Ti:sapphire laser

Theoretical and experimental studies are carried out on the simultaneous dual-wavelength oscillation of a gain-switched Ti:Al2O3 laser, which is electronically tuned with an acousto-optic tunable filter (AOTF). Simultaneous oscillation at two wavelengths is performed by feeding two different radio frequencies (RFs) to the AOTF, although Ti:Al2O3 is known to be homogeneously broadened. Analysis based on semiclassical theory explains the temporal behavior and stability of dual-pulse oscillation, which is achieved by controlling the cavity lifetimes for two operating wavelengths independently. The relationship between gain and cavity loss, which is controllable through the diffraction efficiency of the AOTF by adjusting RF powers, is studied. The effects of variations of the pump pulse energy and in the spontaneous emission intensity have been studied in the numerical laser model for dual-wavelength operation. Because of the competition between the dual-wavelength pulses, the fluctuations in peak power in the experiment were observed to double compared with those observed during single-wavelength operation. Most experimental results of output characteristics agreed qualitatively with those of numerical predictions except for instability, which was significantly lower than the predicted value.