Towards green lasing: ingredients for a green laser diode based on GaInN

Abstract

Laser structures based on GaInN quantum wells were investigated using the variable stripe length technique. Two major problems in designing a green emitting laser diode were identified. The first one is the decrease of the optical confinement for increasing wavelength. To avoid this limitation and to simultaneously maintain good optical confinement we grew samples with lattice‐matched AlInN lower cladding layers. The second major issue is to push the emission of the structures to longer wavelength by increasing the indium concentration in the quantum well. We demonstrate optical gain up to a wavelength of 480 nm (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

450 nm GaInN ridge stripe laser diodes with AlInN/AlGaN multiple cladding layers

“…As shown in Fig. 9, the LD with a cavity length of 1.5 mm demonstrated a threshold current density of 1.15 kA cm −2 , which is a lower value than those in previous reports with AlInN cladding layers 15,[20][21][22][23][24] and not far away from those of the state-of-the-art GaInN LDs (1 kA cm −2 and lower). 30,31) In addition, a 50% η ext from both the facets with a good linearity was simultaneously obtained.…”

“…So far, relatively high threshold current densities (6.7-35 kA cm −2 ) have been reported from the LDs emitting relatively short wavelength regions, 394-415 nm. 15,[20][21][22][23][24] In the meantime, the horizontal optical waveguide is realized by forming a ridge stripe structure after the epitaxial growth. 25,26) The ridge stripe structure is formed by patterning by photolithography and partly etching the top p-type layers above the QW active layer.…”

Current transport through AlInN/GaN multilayers used as n‐type cladding layers in edge emitting laser diodes

“…The reduced efficiency of optical gain at longer wavelengths has been an area of concern [1,2] and until recently green lasers were primarily produced using frequency doubling of infra-red lasers. Among other issues, the challenges in achieving direct green lasing are in incorporating high percentages of indium in the quantum wells, increasing the optical mode confinement at longer wavelengths and in decreasing the mode leakage to the substrate [3].…”

Growth optimization and characterization of lattice-matched Al0.82In0.18N optical confinement layer for edge emitting nitride laser diodes

“…As one of the potential applications, Al 1 À x In x N has been considered as an alternative to Al x Ga 1 À x N as cladding in group III-nitrides laser diodes (LDs), especially for green wavelength emission [3][4][5][6]. Indeed, the refractive index contrast between the GaN waveguide and Al 0.1 Ga 0.9 N cladding diminishes as the emission wavelength moves to the green range (Dn $ 0.053 for l¼430 nm and Dn$0.035 at l¼520 nm [7]), resulting in lower optical confinement in LD structures.…”