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

Abstract

We report a self-induced spatially-coherent dot array consisting of fourteen units of vertical-cavity surface-emitting modes that exhibit spatially uniform spectra. A 47.5 µm total beam width and 0.5° narrow emission are achieved using an oblong cavity enclosed with a flat top mirror, cylindrically curved bottom mirror, and side facet. Notably, terminating the side of the cavity with a perpendicular facet enhances the horizontal propagation, which couples with the vertical resonance in each dot, similar to the case of master lasers in injection-locked lasers that delocalize the modes. Conventional semiconductor lasers, edge-emitting lasers, and vertical-cavity surface-emitting lasers have a Fabry–Pérot cavity; furthermore, emission and resonance are in identical directions, limiting the beam width to micrometers. Though the present structure has the same scheme of propagation, the right-angled facet synchronizes the modes and drastically expands the beam width.

Highly-efficient operation and mode control in GaN-based VCSELs with a curved mirror

“…The curved mirror provided lateral optical confinement to eliminate the diffraction loss, thereby improving the laser characteristics. After the report of operation under pulsed current injection in 2018 [9], blue VCSELs with similar structures, efficient current confinement by ion implantation [10], sub-milliampere operation [11], stabilized lateral modes [12], high efficiency operation up to 13.5% [13] (see Figure 1a), long life reaching 2000 h [14], generation of spatially coherent dot array of VCSEL modes [15], and narrow emission angle of 3.9° for circular aperture [16] and 0.5 degree for oblong aperture [17] have been reported. Recently, we reported CW-operation green VCSELs [18] with milliwatt class outputs and high-efficiency operation [19] (see Figure 1b).…”

“…Figure 1. I-V/L and I-WPE curves of (a) blue [13] and (b) green VCSELs [17] with curved mirror. Insets are emission spectra obtained above threshold currents.…”

Study on Bottom Distributed Bragg Reflector Radius and Electric Aperture Radius on Performance Characteristics of GaN-Based Vertical-Cavity Surface-Emitting Laser

“…In 2003, Park et al reported the operation of a GaN-based VCSEL with monolithic curved mirrors, optically pumped [25]. Over the past few years, various VCSEL structures with curved mirrors have been demonstrated [8,9,[26][27][28][29][30][31][32][33]. Recently, it was demonstrated that upper DBR mirrors can be successfully replaced by high-index contrast gratings (HCG) and monolithic high-refractive-index contrast gratings (MHCG).…”