High-Energy Single-Frequency Millisecond 1336.630-nm Nd:LGGG Amplifier (April 2017)
We demonstrate a high-energy, single-frequency, and millisecond (ms) 1336.630-nm amplifier with high beam quality and narrow-linewidth simultaneously based on the Nd<sup>3+</sup>:(Lu<sub>x</sub>Gd<sub>1-x</sub>)<sub>3</sub>Ga <sub>5</sub>O<sub>12</sub> (Nd:LGGG) disordered crystal for the first time. The amplifier system consists of a polarized single-frequency 1336.630-nm LD oscillator, two-stage Raman fiber preamplifier, and four-stage Nd:LGGG main amplifier. The seed laser pulse energy is amplified up to a record high pulse energy of 2.05 J at a repetition rate of 5 Hz and a pulse duration of 1 ms with linewidth as narrower as 0.5 pm. The beam quality factor is <inline-formula><tex-math notation="LaTeX">${\rm{M}}^{2}\,= \,1.46$</tex-math></inline-formula>. The wavelength of the single-frequency amplifier can be tuned from 1336.600 to 1336.660 nm. All results indicate that the Nd:LGGG is high performance 1.3-μm laser amplification medium, especially for generating the specific wavelength at 1336.630 nm. Moreover, such laser source with the specific wavelength at 1336.630 nm is promising for the development of a high accuracy <sup>27</sup>Al<sup>+</sup> ion optical clock.