Planar Waveguide Amplifiers and Lasers

Abstract

Asymmetric lasing and pumping spa al profile Cylindrical lens Waveguide PumpDiode bar Sapphire Sapphire YAG Fig. 11.4 (a) Schematic of end pumping a planar waveguide using a diode laser. Also shown is the pump laser mode in the waveguide. (b) Schematic of a double core waveguide pumping using a diode bar. 8,15 in planar waveguides needs to be two orders of magnitude greater than that for optical fibers. At higher concentration, the average spacing between Er ions decreases. At close spacings, the Er ions lose the exited energy by a nonradiative process known as up-conversion. Consider two Er ions both in their upper energy levels, in the upconversion process, one electron (in one Er ion) decays nonradiatively to the ground state, transferring its energy to the other Er ion, which gets excited to a higher energy level. The clustering of Er ions in silica glass doped to high Er concentrations accentuates this nonradiative decay mechanism. Up-conversion is less pronounced in other glass types (e.g., soda lime glass due to its cage-like structure) where the atoms in the glass surround each Er ion and prevent clustering. These types of glasses have been used in the study of PWAs. Fiber Amplifiers and Fiber Lasers Downloaded from www.worldscientific.com by UNIVERSITY OF BIRMINGHAM LIBRARY -INFORMATION SERVICES on 03/21/15. For personal use only.