Mode control in long cavity VCSELs with a curved mirror

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).…”

“…Because the typical width of the gain spectrum of InGaN is longer than 10 nm, a subnanometer-wide mode spacing can easily enable multimodal operation of the device. This occasionally causes hopping of the longitudinal mode with changes in the operation current or the environmental temperature, which shift the gain spectrum of the device [14] (see Figure 2a). This instability of the emission wavelength is a critical issue for some applications sensitive to the wavelength, such as those coupled to a grating and atomic clocks.…”

“…Another modification that was observed to be effective was stabilizing the emission wavelength with this long-cavity structure [14]. We inserted a micron-thick layer into each DBR to separate it into two sub-DBRs.…”

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).…”