Generation of powerful 3 microns radiation and its delivery

In some last years mid-infrared Er:YAG laser radiation (2940 nm) found the exploitation in many applications in technology and especially in various medical branches (dentistry, dermatology, cardiology, ophthalmology). Most of them use the Er:YAG laser system working in free-running regime generating the pulses with the length of some hundreds of microseconds. In the presented work we concentrated on the development and optimization of electro-optically Q-switched Er:YAG laser and suitable delivery system. Er:YAG laser operated both in free-running or Q-switched regime was developed and optimized. LiNbO3 Pockels cell was utilized for Q-switching the Er:YAG laser. Single giant pulses with maximal energy 67 mJ and minimal duration 53 ns FWHM were generated for maximal pump energy 131 J and for the optimal Pockels cell parameters (high voltage value 1.4 kV, delay of Pockels cell switching after the flashlamp trigger 450 μs). The Er:YAG laser radiation was effectively delivered by the special COP/Ag hollow glass waveguides with inner/outer diameters 700/850 μm or 320/450 μm, and length from 10 cm up to 1 m. The transmission of the used waveguides was measured to be from 73% to 84% according to waveguide type. With the help of delivery systems, the Er:YAG laser radiation (in the form of long pulses for free-running regime or short pulses for Q-switched regime) was applied to various biological tissue samples to study the basic laser radiation-tissue interactions and treatment possibilities.