High power multi-crystal cw and femtosecond mode-locked oscillators based on Yb:KYW

Abstract

We present results from diode-pumped cw and semiconductor saturable absorber mirror (SESAM) mode-locked resonators containing multiple bulk Yb:KYW crystals. The dual-crystal resonator generated more than 24W of cw-power at a wavelength of 1042nm in a diffraction limited beam with the maximum power limited by the available pump power. Two mode-locking regimes were explored. From the soliton mode-locked oscillator we obtained Fourier limited pulses with a pulsewidth of 450fs at a repetition rate of 79MHz and with an average power of 14.6W. When operating the same resonator in the positive dispersion regime we achieved an output power of 17W. Using a grating compressor these pulses could be compressed to a pulse width of 470fs. Both mode-locked lasers were self-starting and operated stably and in turn key fashion over days and through varying lab conditions. Regarding the power scaling of this type of laser we anticipate further scalability by once again doubling the number of crystals inside the resonator.