Short cavity InGaN-based laser diodes with cavity length below 300μm

摘要

We report on a practical method for developing InGaN-based edge emitting laser diodes of cavity length down to 45 mu m. Samples consisting of one uncoated cleaved facet and one etched facet coated with a high-reflectivity (HR) dielectric distributed Bragg reflector (DBR) exhibit lasing in the continuous wave (cw) regime for cavity lengths down to 250 mu m and lasing under pulsed injection for lengths as short as 100 mu m. For samples having a second HR dielectric DBR, we could demonstrate cw lasing for a cavity length as short as 45 mu m with a threshold current below 10 mA being reported for a 75 mu m long device. Through a systematic study of the threshold current (I-th) and the slope efficiency (eta(s)) as a function of cavity length, it is proposed that the parameters underpinning the evolution of I-th and eta(s) with decreasing cavity length and their overall degradation in the short cavity regime are free carrier absorption, Auger processes and the decrease in the recombination losses due to nonuniform carrier distribution across the multiple quantum well active region.