ABSTRACT
We report on an in-band pumped SESAM mode-locked Ho:CALGO bulk laser with a record-high average power of 8.7 W and an optical-to-optical efficiency of 38.2% at a central wavelength of 2.1 µm. At this power level, the bulk laser generates pulses with a duration of 369 fs at an 84.4-MHz repetition rate, corresponding to a pulse energy of 103 nJ and a peak power of 246 kW. To the best of our knowledge, this is the highest average power and pulse energy directly generated from a mode-locked bulk laser in the 2-3 µm wavelength region. Our current results indicate that Ho:CALGO is a competitive candidate for average power scaling of 2-µm femtosecond lasers.
ABSTRACT
We studied the refractive index and dispersive properties of the tetragonal rare-earth calcium aluminates, CaLnAlO4 (Ln=Gd or Y). Sellmeier equations were derived for the spectral range of 0.35-2.1 µm. The group velocity dispersion (GVD) in CaGdAlO4 is positive at â¼1 µm, 95 fs2/mm and negative at â¼2 µm, -40 fs2/mm. The GVD values for CaYAlO4 are similar. In addition, thermo-optic coefficients, dn/dT, and thermal coefficients of the optical path were determined for CaYAlO4. dn/dT is negative at â¼1 µm, dno/dT=-7.8, and dne/dT=-8.7×10-6 K-1. Thermo-optic dispersion formulas were constructed. The obtained data are of key importance to the design of high-power mode-locked oscillators at â¼1 and â¼2 µm based on such laser hosts.
