Improving optical and electrical properties of InGaN-based green laser diodes by graded-compositional waveguide structure

Abstract

A graded-compositional waveguide structure is proposed to improve the optical field distribution of InGaN-based green laser diodes (LDs). It is found that the optical field leaking into the GaN substrate is suppressed obviously when using the graded-compositional upper and lower waveguide. Owing to the enhancement of refractive index contrast between the waveguide layer and the cladding layer, the optical field confinement factor increases, and the optical field is more concentrated near the active region. Besides, higher output power and lower threshold current are achieved due to reduced electron leakage and increased hole injection. This work provides a theoretical design method for obtaining high-performance InGaN-based green LDs. • A new structure with graded-compositional upper and lower waveguide is proposed. • The optical field leaking into GaN substrate is obviously reduced. • High output power and low threshold current are achieved. • The photoelectric performance of green LDs is significantly improved.