Abstract:
Thulium-doped fiber lasers (TDFL) operating at 2 microns are usually pumped by 790 nm diodes with slope efficiency up to 70% achieved employing the “2-for-1“ process due to cross-relaxation. TDFLs in-band pumped by 1700 nm diodes or with tandem pumping by 1900 nm can provide better efficiency in theory (>80% and >90% respectively) but have not reached their potential so far. Theoretical and experimental research of in-band pumped TDFLs and holmium-doped fiber lasers (HDFLs) will focus on modeling and measurement of physical mechanisms limiting their efficiency performance such as: a) cladding (material) absorption, b) non-radiative transfers and c) spectroscopic parameters (lifetimes, absorption and emission cross-sections) dependent on concentration. Experimental campaign will test the influence of concentration on slope efficiency. Novel fiber doping methods and geometries with structured core will be studied and tested as possible way to improve the efficiency of in-band pumped TDFLs and HDFLs towards its theoretical limits.
Project Aims:
Aim is to study mechanism lowering efficiency of in-band pumped fiber lasers operating at 2 microns such as cladding absorption and phonon-assisted up-conversion. Novel fiber geometries and doping methods increasing efficiency of in-band thulium and holmium fiber lasers are to be proposed.
Co-investigator:
Ing. Richard Švejkar, PhD., Faculty of Nuclear Sciences and Physical Engineering, CTU