High-power DUV picosecond pulse laser with a gain-switched-LD-seeded MOPA and large CLBO crystal

Abstract

We report the generation of a 266 nm deep ultraviolet (DUV) picosecond pulse with an average output power of 14 W by the fourth-harmonic generation (FHG) from two consecutive frequency-doubling stages of a 1064 nm pulse based on a gain-switched-laser-diode (LD)-seeded hybrid fiber/solid-state master oscillator and power amplifier (MOPA) system. Through the gain-switched operation of a narrow-spectral-linewidth distributed-feedback laser diode and by using a Yb-doped fiber and a two-stage <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">N</mml:mi> <mml:mi mathvariant="normal">d</mml:mi> </mml:mrow> <mml:mo>:</mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">Y</mml:mi> <mml:mi mathvariant="normal">V</mml:mi> <mml:mi mathvariant="normal">O</mml:mi> </mml:mrow> <mml:mn>4</mml:mn> </mml:msub> </mml:mrow> </mml:math> solid-state amplifier, we achieved an average power of 46.5 W near the Fourier transform limit for a 13 ps pulse with a repetition rate of 200 kHz. The narrow linewidth pulse characteristics enabled highly efficient frequency conversion, and the efficiency of conversion from 532 to 266 nm was 54%, and from 1064 to 266 nm was 31%. The beam quality factor <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mi>M</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:math> of the generated DUV pulse was below 1.2. The highly efficient FHG process resulted in appeasing thermal stress caused by nonlinear absorption in the crystal, and more than 5000 h of continuous operation were achieved without any power down or beam profile degradation.

Topics & Concepts