Laser diode optical output dependence on junction temperature for high-power laser systems

Abstract

Laser diode optical output is studied and modeled. Four major diode parameters (threshold current, slope efficiency, central wavelength of output, and full-width half maximum of output), which are dependent on diode junction temperature, determine the optical output. The physics and equations representative thereof for each parameter are presented and incorporated into a multiphysics model of a high-power laser system (HPLS) to study the optical power/thermal interactions. Simulations are compared to show how optical power output of an HPLS changes when the temperature dependence of parameters are and are not accounted for in the model. The decrease in laser light intensity out of the HPLS as junction temperature changes is also studied. Intensity is sometimes a more important consideration than optical power because for most applications, laser light is only effective when the output power is focused over a very narrow wavelength range. The research provides higher fidelity diode modeling for effectively understanding optical/thermal interactions and the price to be paid for improper diode thermal management. The research supports our main goal of more accurately representing the thermal loads from the individual components of an HPLS.