Thulium-Doped Fiber Laser and Its Application in Urinary Lithotripsy

Purpose Thulium-doped fiber laser (TFL)-based urological lithotripsy has emerged as a promising technology for treating urological stones in new era of endourological options. The objective of this review is to provide a comprehensive summary of the characteristics of TFL application for lithotripsy and to analyze the research progress of two crucial TFL light sources, quasi-continuous (QCW) TFL and main oscillation power amplification (MOPA) TFL. Methods The data about the potential efficiency of TFL in clinical applications and the status of pulsed TFL studies were gathered through a manual search of TFL-related literature in the SCI, SSCI, A&HCI, IE, PubMed databases to assess the performance issues associated with application of thulium laser for urinary tract stone surgery. Results TFLs can ablate stones mainly through photothermal and micro-explosive effects. In clinical trials, thulium laser has been established to be superior to holmium laser in terms of lithotripsy efficiency, tissue damage, lithotripsy retreating effect, thermal effect, intraoperative visualization, and postoperative lithotripsy-free rate, which is more widely used currently. Among the various pulsed TFLs, QCW TFL provides flexible beam waveform, high electro-optical conversion efficiency, high heat dissipation performance, and low material maintenance requirements. MOPA TFL can flexibly affect the morphology of the output pulse within a wide range while significantly increasing the output power. Conclusion TFL represents a safer, more effective and comprehensive tool for the treatment of urinary stone. Although QCW TFL is currently the mainstream laser source for lithotripsy, we anticipate that MOPA technology has the potential to offer number of advantages while it has not yet received sufficient attention. Further studies are still needed to optimize the performance of pulsed TFLs to facilitate the development of thulium laser lithotripsy.