Scaling and passively Q-switch operation of a Nd:YAG laser pumped laterally through a YAG prism

• Scaling of a Nd:YAG laser pumped directly through a YAG prism is reported.
• Pulses with 22.1 mJ energy are obtained in free generation regime.
• The first passively Q-switched Nd:YAG/Cr4+:YAG-YAG prism laser is realized.
• Q-switch laser pulses with 0.29 mJ energy and 11 ns duration are obtained.

We report on scaling of a laser configuration in which a YAG prism is used to couple the pump beam from a fiber-coupled diode laser directly into a Nd:YAG medium. Several resonator geometries have been investigated. In free generation regime laser pulses at 1.06 μm with energy of 22.1 mJ for the pump energy of 44.6 mJ were obtained from a 10.0 mm long, 1.0-at% Nd:YAG single crystal that had the high-reflectivity mirror coated directly on one of the laser crystal surface. The slope efficiency was 0.51. A similar uncoated Nd:YAG crystal placed in a plane–plane resonator delivered laser pulses with 17.8 mJ energy under the pump with 45.4 mJ energy, at 0.40 slope efficiency. Further, a passively Q-switched Nd:YAG/Cr4+:YAG composite ceramic laser pumped through a YAG prism has been built. Using a Cr4+:YAG saturable absorber of 0.85 initial transmission the device delivered laser pulses with 0.29 mJ energy and 11 ns duration. The output performances are compared to those obtained in a classical end-pumping scheme.