Picosecond laser source at 1 MHz with continuous tunability in the visible red band

We report the first demonstration to our knowledge of a continuously tunable picosecond laser operating around 1 MHz. The emission can be tuned from 640 to 685 nm and the repetition rate from 200 kHz to 1 MHz with a pulse duration of less than 200 ps. The system is based on a Nd:YVO4 passively Q-switched microchip laser providing a few tens of nanojoules per pulse. Two cascaded stages of amplification are then used to increase the pulse energy to several microjoules. The frequency-doubled radiation is then used to pump a periodically poled niobate lithium (PPLN)-based optical parametric generator in an all-solid-state architecture. Twenty nanojoules of tunable signal radiation are obtained. We also demonstrated 300-ps pulses generation in the UV (355 nm) at 1 MHz. (C) 2003 Elsevier Science B.V. All rights reserved.