Pulsed HF chemical lasers oscillating in the midinfrared region of the spectrum where water can strongly absorb are suitable for the organic tissue ablation. For such a medical application, a flexible energy delivery system using an optical fiber is indispensable. The fluoride glass optical fiber may be used for low-loss optical energy delivery of the pulsed HF laser. Using an intracavity CO2 absorption cell, we have optimized pulsed multiline HF chemical laser spectrum for low-loss energy delivery through a fluoride glass optical fiber whose transmission loss is theoretically estimated to be minimum around 2.5 μm. The fractional output energy of P1-0(3) and P 1-0(4) lines, which are sitting in the lowest loss spectral region of the practical fluoride glass fiber, exceeded half the multiline output energy using a line selective intracavity CO2 gas cell. The P 1-0(4) line extracted from the resonator with a diffraction grating was successfully delivered through a 3-m-long commercial fluoride glass fiber (core/cladding diameter=450/500 μm). The delivered energy of 11.9 mJ was achieved with the corresponding energy fluence of 12 J/cm2 and peak intensity of 22 MW/cm2 at the exit core surface without optical damage.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)