Nd:Glass Ring Regenerative Amplifier Using Telescopic Geometry for High Output Energy with Good Beam Quality

To achieve high output energy by generating a large gain mode volume, a Nd:phosphate glass ring regenerative amplifier with a built-in 1:1 telescope was proposed as a part of a terawatt chirped-pulse amplification Nd:glass laser, and its performance was characterized. In this ring regenerative amplifier, an input energy of 80 pJ could be amplified up to 33 mJ, and the output beam size was 2.3 mm in width and 2.0 mm in height. The amplified spectrum showed that high amplification could be obtained without a noticeable gain narrowing from the injected spectrum of 6 Å bandwidth.