P2-25 Comparison ofLasing Performance ofTm,Ho:YLF Laser using Single and Double Cavities

An eye-safe 2u.mTm,Ho:YLF operated in either the cw or pulse oscillation mode has the potential application in laser remote sensing. Especially, a Ho-doped laser has an advantage for suppression ofa relaxation oscillation (Elder et al., 1998). On the other hand, the YLF crystal as a host crystal has excellent characteristics such as a low thermal lens effect because of negative dn/dt (Razunova et al., 1996), and an easy polarized oscillation because of its uniaxial structure. In addition, relatively long lifetime of a Tm,Ho:YLF laser as compared with a Tm,Ho:YAG laser (Payne et al., 1992) is useful for Q-switch operation. Although there are several techniques for obtaining stable single-longitudinal mode oscillation ofTm Ho:YLF laser, adoption ofa microchip laser with the double cavity is considered to be one of the most suitable methods (Yokozawa et al., 1998). In this work we report comparison of the lasing performances of single-longitudinal mode Tm,Ho:YLF lasers using single and double cavity configurations, respectively. uncoated but merely polished. Slightly separated from the polished surface of the crystal, an output mirror having a 99% reflectivity at 2.1urn is employed. It should be noted that such a space between the output mirror and the polished surface of the laser crystal plays an important role as an etalon whose distance can be controlled easily by adding voltage directly to the mirror holder made of PZT ceramics.