Theory and optimization of lens ducts.

Lens ducts are simple optical devices that have found application in the coupling of pump radiation from extended two-dimensional semiconductor laser diode arrays into solid-state laser gain media. The operation of these devices relies on the combined effects of lensing at their curved input surface and channeling by total internal reflection off their canted planar sides, to contain and couple semiconductor diode laser light efficiently to the input face of a solid-state laser crystal or glass. The lens duct provides a robust method for amplifying the irradiance of laser diode array pump sources and has made possible a scalable diode end-pumping architecture that offers the opportunity to expand significantly the number of ions and transitions that can be practically engaged in diode-pumped solid-state laser systems. An analytic model that describes the transfer efficiency of lens ducts and aids in the optimization of their design is presented.