High-average-power (>20-W) Nd:YVO_4 lasers mode locked by strain-compensated saturable Bragg reflectors

Abstract

Strain-compensated double InGaAs quantum-well saturable Bragg reflectors (SBR’s) with high damage thresholds have been developed for use as mode-locking elements in high-average-power neodymium lasers. $\mathrm{Nd}:{\mathrm{YVO}}_4$ lasers have been developed with these new SBR’s, which produce transform-limited pulses of 21-ps duration at 90 MHz and an average power of 20 W in a diffraction-limited output beam. The peak pulse power at an output power of 20 W was 10.6 kW. A comparison of the operating parameters of strained single and strain-compensated double-well SBR’s indicates that the damage threshold increased by a factor of at least 2–3. Long cavity laser variants were investigated to assess the limitations of further power scaling. At a repetition frequency of 36-MHz stable mode-locked pulses with peak pulse powers of 24.4 kW and pulse energies of 0.6 µJ could be generated.