Recent advances in Al-free 980-nm pump lasers

Abstract

This paper describes state-of-the-art aluminum-free 980-nm laser diodes which are intended for pumping erbium doped optical fiber amplifiers (EDFA's). There are three principal issues for these laser diodes to be considered for the EDFA applications: light output power, efficiency of coupling the power into a fiber, and reliability. It has been shown that the lasers can launch 400 mW in single transverse mode of operation into free space. A coupling efficiency of 53% and a fiber-coupled power of 58 mW have been demonstrated. Because the Al-free 980-nm lasers are new, their lifetimes have not yet been thoroughly studied. However, some tentative experiments indicate that extrapolated lifetimes may be several hundred thousand hours at reasonable power levels. Thermal roll-over tests prove that the lasers withstand high currents and temperatures without any sign of degradation.