Temporally stretched Q-switched pulses in the 2 μm spectral range

Abstract

A Q-switched Ho:YAG laser, longitudinally in-band pumped by a thulium fiber laser at a wavelength of λ = 1920 nm was designed in order to temporally stretch the Q-switched pulses at the fundamental wavelength. This was realized by two different methods:(a) wavelengths with a small cross section for stimulated emission have been selected, which leads to a pulse duration of 162 ns at 2128 nm compared to 32 ns at a wavelength of 2098 nm with energies around 1 mJ, (b) additionally intracavity second harmonic generation in the overcoupling regime has been used to further increase the pulse duration up to 300 ns at 1 mJ.

Resection of Calcified Aortic Heart Leaflets In Vitro by Q-Switched 2 µm Microsecond Laser Radiation

“…The catheter systems used in these trials were based on the already known technology. 19,20 With the new system, an isolation of the pulmonary valve was achieved for 21 min. The blood flow was maintained by the contraction of the heart, supported by an internal microaxial pump (2.1 l/min).…”

“…Brecht et al demonstrated in porcine models that an isolation of the pulmonary valve is possible without external circulation support. The catheter systems used in these trials were based on the already known technology . With the new system, an isolation of the pulmonary valve was achieved for 21 min.…”

Gain broadening and mode-locking in overcoupled second harmonic Q-switched microsecond pulses

“…In this so called overcoupling regime the pulse energy only decreases slightly with increasing conversion efficiency while the pulse duration increases significantly. Thus the overcoupling effect provides a method to adjust the pulse duration without significant loss of energy [11][12][13]. Generation of microsecond pulses with durations of 3.2 μs at 3.4 mJ by utilizing this technique has been demonstrated at a wavelength of 527 nm [11].…”