Abstract

By harmonically modelocking a Nd:YAG laser 31 ps pulses at 0.5 GHz repetition rate have been obtained.¹ By using YLF, shorter pulses, 9.1 ps, at 0.5 GHz repetition rate have been achieved. Nd:Glass has a much wider bandwidth and potentially can achieve a shorter pulsewidth. Our group had achieved a pulsewidth less than 10 ps at a repetition rate of 100 MHz. With further compression, the pulses have been shortened to 30 fs.² In this work, we have investigated the modelocking of a Nd:phosphate glass laser using high frequency gallium-phosphate (GaP) acousto-optic modulators (AOMs). We have characterized four different acousto-optic modulators. The single pass insertion losses of the four tested modulators ranges from 5% to 13%. The modulation depths of these AOMs with 0.3 W rf power are about 25%. The modulation depth and dynamic loss increase with increasing driving rf power and decrease with increasing frequency. We have achieved modelocking of a short cavity (26 cm long) cw Nd:phosphate laser at 500 MHz repetition rate with the average output power of 20 mW, generating 10 ps pulses at 1.054 µm.

© 1990 Optical Society of America