Room temperature continuous-wave operated 2.0-W GaN-based ultraviolet laser diodes

Abstract

Temperature characteristics of near-UV laser diodes (LDs) with a lasing wavelength of 384 nm are investigated. The characteristic temperature of threshold current (T0) of the UV LDs is low. Thus, the performance of the UV LDs under continuous wave (CW) operation is not as good as under pulsed operation especially at a high injection current. In addition, it is found that self-heating is a key factor for CW characteristics of the UV LDs, where suppression of the self-heating by using thick waveguide layers can increase the critical current of thermal rollover of the UV LD’s operation. A high CW output power of 2.0 W is achieved for an InGaN near-UV LD with the n-side down on a sub-mount, whose threshold current density is 1.27 kA/cm2 and the highest wall plug efficiency (WPE) is approximately 15.9% at an injection current of 1.2 A.