High-Power GaN-Based Vertical-Cavity Surface-Emitting Lasers with AlInN/GaN Distributed Bragg Reflectors

Abstract

High-efficiency and high-power operation have been demonstrated for blue GaN-based vertical-cavity surface-emitting lasers (VCSELs) with AlInN/GaN distributed Bragg reflectors. The high-efficiency performance was achieved by introducing a novel SiO2-buried lateral index guide and adjusting the front mirror reflectivity. Lateral optical confinement has been shown to greatly lower the otherwise significant loss of transverse radiation exhibited by typical VCSELs based on GaN. Employing a long (10λ) cavity can also enhance the output power, by lowering the thermal resistance of the VCSEL and increasing the operating current associated with thermal rollover. This modification, in conjunction with optimized front mirror reflectivity and a buried SiO2 lateral index guide, results in a blue VCSEL (in the continuous wave mode with an 8 μm aperture at 20 °C) having a superior differential quantum efficiency value of 31% and an enhanced 15.7 mW output power. This unit also exhibits a relatively high output power of 2.7 mW at temperatures as high as 110 °C. Finally, a 5.5 μm aperture VCSEL was found to generate a narrow divergence (5.1°) single-lobe far field pattern when operating at an output power of approximately 5 mW.

Influence of Various Bottom DBR Designs on the Thermal Properties of Blue Semiconductor-Metal Subwavelength-Grating VCSELs

“…Due to the matching between the lattice constants of AlInN with 18% indium content and GaN [8,35,36], such mirrors are expected to show superior mechanical stability in comparison to the other two constructions. The indium content reduces the refractive index contrast and power reflectance of 99.9% can be obtained with 47 DBR pairs [1,8]. The large number of DBR layers, together with the low thermal conductivity of AlIn0.17N at 4.87 W/(m·K) [11], contributes to the significant thermal resistance of the device.…”

“…Gallium nitride-based vertical-cavity surface-emitting lasers (VCSELs) are currently under development, with potential for use as light sources in optical communication, optical storage, laser printers, and biosensors [1,2,3,4]. GaN-based VCSELs could also provide the missing green element in designs for white light emitting pico-projectors, laser headlamps, and high power displays [1,2,3,4,5]. One of the main issues hindering the commercial production of nitride-based VCSELs is the fabrication of distributed Bragg reflectors (DBRs) with satisfactory optical, thermal and electrical properties.…”

49‐2: Invited Paper: Blue and Green VCSEL for Full‐Color Display

“…Since continuous oscillation of the room temperature was first reported in 2008 [2], many studies in this field have been published. Since 2018, multiple organizations have successively announced blue VCSELs driven by a high efficiency of approximately 10% [3,4], indicating that the research phase of this device has ended and practical applications are now the focus in the field. Unlike materials composed of gallium arsenide (GaAs), which have been widely used in VCSELs and are suitable for wavelengths ranging from red to infrared, materials composed of nitride (GaN) can emit light in a wide range of wavelengths (from ultraviolet to green) due to their wide band gap.…”

Impact of the active area position in a nitride tunnel junction vertical-cavity surface-emitting laser on its emission characteristics

“…This can be one of the reasons why VCSELs with ITO achieve the highest output powers. The ITO VCSEL presented recently by the Faculty of Science and Technology from Meijo University and R&D Laboratories, Stanley Electric Co. achieved almost 16 mW output power in CW operation [7].…”