Abstract

The mode-locked Nd:glass laser is of interest as a source of short pulses because of its large fluorescence bandwidth (5.3 THz). This lasing medium is particularly suited to pumping by laser-diode arrays, and the performance of several AM mode-locked laser-diode-pumped Nd:glass lasers has been reported.^1,2 We present what we believe to be the first report of an FM mode-locked laser- diode-pumped Nd:glass laser. The laser cavity used in our experiment was an astigmatically compensated 3-mirror cavity. The active medium, a 1.2 mm thick disk of highly doped LG760 glass, was inserted at the focus of the cavity at Brewster's angle. With 1.5% output coupling we have obtained a power of 35 mW for 400 mW incident on the glass. The FM modulator was a Brewster-angled LiNbO₃ crystal. Its insertion loss was determined to be 3%. The modulator was driven at a 235 MHz, by 1-2 W of rf power. The phase retardation was 0.7 rad. The pulse duration, which was measured by means of standard autocorrelation techniques, was 9 ps (assuming a Gaussian pulse shape), and the laser bandwidth when mode-locked was 71 GHz. The maximum mode-locked power output was 14 mW. Detailed performance characteristics of this laser will be presented, and future development of this system will be discussed.

© 1990 Optical Society of America