Application of a quasi-continuous wave thulium fiber laser in human urinary stone fragmentation

A thulium fiber laser (TFL) operating in quasi-continuous wave (QCW) mode at 1940 nm wavelength with suppressed relaxation oscillation (RO) is presented. An all-fiber optical damper design is introduced which suppressed the RO by mechanism of reverse saturable absorption. The QCW-TFL was used for urinary stone fragmentation, where the effect of peak power and repetition rate on the fragmentation rate and stone surrounding temperature (SST) were studied. A directly proportional relation between the peak power and repetition rate with both fragmentation rate and SST was observed. To counter the SST rise different irrigation rates were used, which indicated that higher irrigation rate can allow the use of higher peak power and higher repetition rate. Which can yield a higher fragmentation rate and shorter operative time.