Abstract

Laserlight with a wavelength of about 2 μm is interesting for a variety of applications such as LIDAR and gas sensing as well as medical applications. To date, the available medical 2 μm laser systems offer either high continuous-wave (cw) powers generated by fiber lasers (LISA Laser Products OHG, IPG Photonics Corp.) or high pulse energies achieved with flashlamp-pumped systems (LISA Laser Products OHG, Quanta Systems S.p.A.). A tunable pulsed laser system operating in the window between these two extremes and generating short pulses with high energies at high repetition rates could open the way to new medical procedures. A possible design is based on Tm or Tm:Ho doped laser rods which can be side-pumped by commercially available qcw laser diodes around 785 nm. With such a design a 3 % doped diffusion-bonded Tm:YAG rod with a diameter of 3 mm and a length of 105 mm produced 120 W cw power [1], while the rod had to be cooled to −12 °C. Another approach demonstrated a pulsed operation of Tm:YAG and Tm:Ho:YAG at room temperature in a side-pumped geometry with energies up to 10 mJ at 10 Hz [2]. In general, Tm lasers are mainly operated in cw (Quanta Systems S.p.A.) and Tm:Ho lasers are usually operated in a pulsed way or by Q-switching due to their higher gain [3].

© 2013 IEEE