True-Blue Nitride Laser Diodes Grown by Plasma-Assisted Molecular Beam Epitaxy

We demonstrate true-blue (450--460 nm) nitride-based laser diodes (LDs) grown by plasma-assisted molecular beam epitaxy (PAMBE) on $c$-plane GaN substrates operating in continuous wave mode. The maximum optical power measured for these LDs is 80 mW, while the lifetime at the optical power of 10 mW is longer than 2000 h. We present a new LD design consisting of a separate confinement heterostructure with GaN claddings and thick In 0.08 Ga 0.92 N waveguides. We show that the key element responsible for the improvements in performance of the true-blue PAMBE LDs is the growth of InGaN quantum wells using a high nitrogen flux.