Frustrated Total Internal Reflection Q-switched Er:YAG and CrEr:YSGG Lasers

Q-switched Er:YAG and CrEr:YSGG lasers are of great interest for many applications in laser medicine and time resolved infrared spectroscopy due to the very high absorption of the 3 µm- radiation in water. The light modulators based on the effect of frustrated total internal reflection (FTIR) [1] appear to be very well suited for Q-switching of these lasers [2, 3, 4]. In this paper, the results of Q-switching of 2.94 µm Er:YAG, 2.79 pm and 2.70 µm CrEr:YSGG lasers with a specially developed FTIR modulator [4] will be presented. The wavelength of 2.70 pm is generated with a CrEr:YSGG laser in a dispersive resonator [4]. The energy output curves of single giant pulses are shown in Fig. 1. The correlations between the pulse energy and the pulse width for these wavelengths in the Q-switching regime have been investigated (Fig. 2). Ablation rates of corneal tissue at different fluences and histological evaluation of the laser induced thermal damage will also be presented and discussed. As a result, Q-switched erbium lasers seem to be a promising tool for many applications in laser surgery. This work is supported by the BMBF (german department for education, research, and technology) within the contract 13N6346/0.