cw surface-emitting grating-coupled GaAs/AlGaAs distributed feedback laser with very narrow beam divergence

Abstract

Firstorder gaincoupled (Ga,In)As/(Al,Ga)As distributed feedback lasers by focused ion beam implantation and in situ overgrowth

Single-lobe, surface-normal beam surface emission from second-order distributed feedback lasers with half-wave grating phase shift

“…External-cavity controlled VCSELs have demonstrated 1,2 high coherent powers ͑Ͼ0.5 W͒, but with low efficiency and in configurations of doubtful long-term reliability. Horizontal-cavity, SE devices incorporating second-order, index-coupled, distributed-feedback ͑DFB͒ gratings have been studied since the early 1970s, [3][4][5][6][7][8][9] and were found, both theoretically 8,10,11 and experimentally, 3,12,13 to favor lasing in an antisymmetric mode ͑i.e., a two-lobed beam pattern͒, since such a mode has the least radiation losses, and subsequently is the one favored to lase. Furthermore, due to strongly nonuniform guided-field intensity profiles, such devices become multimode via gain spatial-hole burning.…”

Design for high-power, single-lobe, grating-surface-emitting quantum cascade lasers enabled by plasmon-enhanced absorption of antisymmetric modes

“…2 Research on GCSELs started in the early 1970s and was focused on near-infrared (IR)-emitting devices. [3][4][5][6] It was found for TE-polarized lasers that, in accordance with theory, 7 the longitudinal mode favored to lase is the antisymmetric one (i.e., a mode whose far-field pattern consists of two lobes) due to its inherent low radiation loss and subsequent low threshold gain. Several approaches have been proposed and demonstrated for realizing operation in a singlelobe beam 8 with the most successful ones being those involving no penalty in efficiency: central grating p phase shift [9][10][11] or chirped grating corresponding to a p phase shift.…”

Surface-Emitting Lasers with Surface Metastructures

“…Therefore, there is a vertical momentum component of the antisymmetric BIC for surface emission, as schematically shown in Figure 8. This proposed BSW-SEL with 1D or 2D periodicity has unique features compared with the 2D PCSEL [30,31] and 1D PCSEL (i.e., second-order distributed feedback laser) [32,33]. The 1D and 2D PCSELs works with the guided mode of a waveguide, whereas the BSW-SEL works with a BSW located in the band gap at kx > 0 of the dispersion of the DBR in Figure 9.…”

“…Due to the limited computational resource, the horizontal (along x direction) calculation domain of the finite-size BSW-SEL structure is 50 µm. Along the x direction, a standing wave is formed by the distributed feedback effect like in the 1D second-order distributed feedback laser [32,33,[52][53][54]. In the z direction, considerable light is diffracted upward for surface emission, and at the bottom side the field is decayed because of the BSW in the finite-pair DBR and the reflection of the finite-pair DBR, resulting in less diffracted light emitting downward.…”

“…The solitary HCG-VCSEL and VCSEL have limited single-mode output power and a large divergence angle, making them not good for sensing applications and optical interconnects. One-dimensional (1D) and 2D photonic crystal surface-emitting lasers (PCSELs) can achieve single mode operation with high power and a low divergence angle based on the 1D and 2D distributed feedback over a large area [30][31][32][33]. Since these PCSELs are based on the first-order diffraction for surface emission, the efficiency of the PCSEL is limited because theoretically the downward radiation (50%) of the first-order diffraction power is lost.…”