Abstract

Optical parametric oscillators (OPOs) are attractive tools for research on tissue ablation upon infrared irradiation. Here, we report on the performance of several mid-infrared nonlinear crystals, namely type I and type II AgGaS₂ (AGS) and type I CdSiP₂ (CSP), used in synchronously-pumped OPOs tuned to a wavelength of 6.45 μm, coinciding with the amide II absorption band of proteins. CSP-based OPOs clearly exhibit better performance in comparison to AGS: First, the oscillation threshold with CSP is three (five) times lower than type II (type I) AGS. Second, the idler conversion efficiency is more favourable for CSP and allows reaching 27.5 mW of idler average power, while 13 and 6 mW are obtained with type II and type I AGS, respectively. Such performance makes CSP suitable for high power 6.45 μm surgical applications. Preliminary ablation experiments on liver tissues with our CSP-based OPO highlight the promising future of CSP in medical applications.

© 2011 OSA/SPIE