Abstract:
Background High-power narrow-linewidth, single-frequency 589 nm sodium guide-star lasers are essential for astronomical adaptive optics. A widely adopted approach to generating high-quality, quasi-continuous-wave (QCW) pulsed guide-star sources is sum-frequency mixing of Nd:YAG lasers operating at 1319 nm and 1064 nm.
Purpose However, parasitic self-oscillation near 1064 nm depletes the stored energy in Nd:YAG, rendering efficient high-power amplification at 1319 nm a critical challenge.
Methods To suppress this oscillation, we employ Sm,Nd:YAG as the gain medium of a partially end-pumped slab (Innoslab) amplifier, exploiting the strong absorption of samarium near 1064 nm to raise the parasitic-oscillation threshold.
Results Experimentally, the amplifier produced QCW single-frequency output at 1319 nm with an average power of 196 W and an optical-to-optical efficiency of 14.2%, operating at a repetition rate of 500 Hz with a pulse width of 155 μs. The beam-quality factors M2 were 1.57 and 1.48 in the horizontal and vertical directions, respectively.
Conclusions These results confirm Sm,Nd:YAG as an effective gain medium for efficient, high-power single-frequency amplification at 1319 nm. To our knowledge, this represents the highest output power reported for a 1319 nm single-frequency Innoslab amplifier, supporting next-generation sodium laser-guide-star adaptive-optics systems.
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