<title>Modeling of multiwatt cw diode-pumped double-cladded fiber lasers for medical applications</title>

Abstract

Theoretical modelling of high-power thulium-sensitised holmium fluorozirconate glass (Tm:Ho:ZBLAN) fibre lasers operating on the 2 tm transition in holmium is presented. High output power in single-mode is achieved by pumping the inner cladding of double clad fibre with single-mode core with high-power multimode cw diode lasers. The higher output powers possible with the doublecladded fibre laser (or DCFL) over the core-pumped fibre laser means that these particular lasers are suited to a number of medical applications which require output of high power and low divergence. In a preliminary step to optimise these devices, a computer model has been developed to analyse the performance ofthe device when the length ofthe fibre configuration and doping are varied. It is shown that the form of the coupling coefficient which relates the transfer of power from nonabsorbing modes to absorbing modes which propagate within the inner cladding and core ofthe fibre is paramount to the operation ofthe DCFL.