In-phase supermode operation in GaN-based vertical-cavity surface-emitting laser

Abstract

A phase-locked ring-array GaN-based vertical-cavity surface-emitting laser (VCSEL) was demonstrated using a floral-patterned structure, based on a buried-SiO2 lateral optical confinement technique. This structure enabled the realization of evanescently coupled waveguides in the circumferential direction with a high differential quantum efficiency of 30%, even in a blue GaN-based VCSEL. A coupled ring array with eight optical spots produced a very narrow divergence beam of 2.8° with an on-axis far-field emission. These results, together with single-longitudinal-mode operation in the lasing spectrum, provide evidence that the proposed GaN-based VCSEL exhibits in-phase supermode operation.

Narrow Emission of Blue GaN-Based Vertical-Cavity Surface-Emitting Lasers With a Curved Mirror

“…Kuramoto et al used GaN/AlInN as the lower DBR and reported a 10 λ resonator with an aperture diameter of 5.5 μm, output power of 5 mW, and FFP divergence angle of 5.1°, with a SiO 2 buried mesa structure [10]. This structural approach has been used to fabricate coupled devices that produced a supermode with a FFP divergence of 2.8° [13]. However, the FFP of such a structure does not form an ideal Gaussian, potentially limiting coupling efficiency.…”

Spontaneously implemented spatial coherence in vertical-cavity surface-emitting laser dot array

“…They can function without subwavelength structures or multiple non-monolithic lasers. Arranging emitters in a ring configuration widens the beam waist 12 , lowers the heat generation by emptying the inner part surrounded by these emitters, and narrows emissions. One remaining drawback of a self-induced coherent array is the complexity in establishing coupling.…”

“…However, increasing the number of emitters can exponentially deteriorate their control. Thus, the maximum number of VCSELs in an array is limited 13 , with a width of approximately 10 µm 12 .…”

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

“…18) This extremely high value of 50 cm −1 represents more than two-thirds of the total internal loss in VCSELs with a lateral anti-guiding structure, leading to superior performance such as lower threshold current, higher efficiency, and higher light output power (LOP) compared to anti-guiding VCSELs. 18,23) Several research groups have developed various lateral index guide structures in GaNbased VCSELs by employing Si-diffusion confinement, 15) a photoelectrochemically etched air-gap aperture, 14,29) a SiO 2 -buried lateral index guide, 18,20,23,26,27) a Nb 2 O 5 convex structure, 19) a monolithic curved mirror, 21,25) and tunnel junction intracavity contact. 11,22,28,[30][31][32] Among them, a high LOP of 22 mW, an external differential quantum efficiency (η d ) of 40%, and a wall plug efficiency (WPE) of around 10% have been demonstrated by incorporating the SiO 2 -buried lateral index guide.…”