Nano-height cylindrical waveguide in GaN-based vertical-cavity surface-emitting lasers

Abstract

We have proposed a novel nano-height cylindrical waveguide in blue GaN-based vertical-cavity surface-emitting lasers (VCSELs). The proposed 5 nm step height cylindrical waveguide using simple processes provides lateral optical confinement and excellent performance in terms of light output power (LOP) and wall plug efficiency (WPE). A fabricated multi-mode VCSEL with 7 μm emission diameter achieved a LOP of 23.7 mW, maximum external differential quantum efficiency of 43.6%, and WPE of 10% under continuous wave operation at 20 °C. Additionally, a single-mode VCSEL with 3.3 μm emission diameter exhibited LOP of more than 5 mW and WPE of 9.9%.

Progress of GaN‐Based Optoelectronic Devices Integrated with Optical Resonances

“…Recent numerous GaN-based VCSELs have adopted the AlInN/GaN bottom DBRs to achieve high performances. [78][79][80][81] In 2016, Ikeyama et al proposed a GaN VCSEL with a top 8-pair Nb 2 O 5 /SiO 2 DBR and bottom 46-pair AlInN/GaN DBR. [82] The reflectivity of two DBRs were both designed to be 99.9% at the lasing wavelength of 405.1 nm.…”

“…Recent numerous GaN‐based VCSELs have adopted the AlInN/GaN bottom DBRs to achieve high performances. [ 78–81 ] In 2016, Ikeyama et al. proposed a GaN VCSEL with a top 8‐pair Nb 2 O 5 /SiO 2 DBR and bottom 46‐pair AlInN/GaN DBR.…”

Impact of p-AlGaN/GaN hole injection layer on GaN-based vertical cavity surface emitting laser diodes [Invited]

“…Lateral optical mode confinement can be realized by using the buried SiO 2 layer below indium-tin-oxide (ITO), where the design can also reduce the internal loss [9] . However, an even easier method to achieve the lateral mode confinement is locally varying the cavity length, and therefore a nano-height cylindrical waveguide structure has been reported [10] . Another obstacle that hinders the improvement for the laser power is low hole injection, which arises from the current crowding effect at the aperture periphery and the hole blocking effect by the p-AlGaN electron blocking layer (p-EBL).…”

Aperture diameter dependences in GaN-based vertical-cavity surface-emitting lasers with nano-height cylindrical waveguide formed by BCl3 dry etching

“…Very recently, Kuramoto et al have developed a nano-height cylindrical waveguide (NCW) structure which was simply formed by a chlorine-based single dry etching process in GaN-based VCSELs. 22) A 5 nm high cylindrical step at the center of the device sufficiently provides a relative refractive index contrast, Δn/n, of 0.17% as the optical confinement, and the current confinement was simultaneously achieved due to a so-called dry etching damage which was originally demonstrated by Cosendey et al 25) Even with such a simple process for the current/optical confinement in Ref. 22, the GaN-based VCSELs with 7 and 3.3 μm NCW apertures have shown superior device characteristics, a 23.7 mW maximum LOP and a 43.6% external differential quantum efficiency for the 7 μm aperture case.…”

“…22) A 5 nm high cylindrical step at the center of the device sufficiently provides a relative refractive index contrast, Δn/n, of 0.17% as the optical confinement, and the current confinement was simultaneously achieved due to a so-called dry etching damage which was originally demonstrated by Cosendey et al 25) Even with such a simple process for the current/optical confinement in Ref. 22, the GaN-based VCSELs with 7 and 3.3 μm NCW apertures have shown superior device characteristics, a 23.7 mW maximum LOP and a 43.6% external differential quantum efficiency for the 7 μm aperture case. 22) At the same time, details of the etching process and its current blocking characteristics were not described yet, and the GaN-based VCSELs with wider NCW structures more than 7 μm diameter have not been investigated.…”