title: High-energy pulsed Raman fiber laser for biological tissue coagulation.
abstract: We demonstrate a high-energy pulsed Raman fiber laser (RFL) with an emission wavelength of 1.44 μm, corresponding to an absorption peak of water. Microsecond pulses with >20 mJ/pulse and >40 W peak power were generated, well above the threshold for tissue coagulation and ablation. Here, we focus on the optical characterization and optimization of high-energy and high-power RFLs excited by an ytterbium fiber laser, comparing three configurations that use different Raman gain fibers, but all of which were prepared with a one-side opened, free-run mode without output mirrors. We show that the free-run configuration can generate sufficiently high energy without requiring a closed cavity design. Experimental RFL characteristics corresponded well with numerical simulations. We discuss the Stokes beam generation process in our system and loss mechanisms mainly associated with fiber Bragg gratings.
authors.forename: Hyoung Won
authors.initials: HW
authors.lastname: Baac
authors.forename: Néstor
authors.initials: N
authors.lastname: Uribe-Patarroyo
authors.forename: Brett E
authors.initials: BE
authors.lastname: Bouma
mesh_terms: D000818:Animals; D003198:Computer Simulation; D004947:Esophagus / Q000502:physiology; D017075:Laser Coagulation; D013059:Spectrum Analysis, Raman; D034421:Sus scrofa; D058067:Wavelet Analysis