Amplification of narrow line LiF:F2+∗∗ color center laser oscillation

A nanosecond pulsed LiF:F2+∗∗ color center master oscillator and power amplifier scheme is presented. Maximum amplified pulse energies of ∼15 mJ near 930 nm are achieved, with an amplification gain of more than 35× under less than 50 mJ of absorbed pump energy. Furthermore, flexibility in the amplifier design should allow for additional improvements through steps such as saturating the passive losses in the crystal. We also discuss the optimization of color center crystal preparation, which has facilitated the growth of LiF:F2+∗∗ color center crystals with large absorption coefficients (from 2 to 8 cm−1 at the maximum near 600 nm). Passive losses in these crystals are estimated to be less than 0.08 cm−1 at the oscillation wavelength and are attributed to the presence of “F2+∗∗-like” color centers.