Theoretical investigation of static and dynamic characteristics of vertical-cavity surface-emitting lasers with incorporated two-dimensional photonic crystals

Abstract

A dynamical model of oxide-confined Vertical-Cavity Surface-Emitting Lasers (VCSELs) with two-dimensional photonic crystals (PCs) incorporated within them so called PC-VCSELs is presented and used to optimise designs for high-power single-mode operation. Three PC-VCSEL designs are considered: (I) with holes in the top DBRs, (II) with PC holes situated between their DBRs and (III) with PC holes etched through the entire VCSEL. A simulated design for a PC-VCSEL of type (I) with holes of d = 2 µm diameter, a = 4 µm lattice constant (d/a = 0.5) and 2.2 µm depth was found to improve the single mode behaviour but not enough to establish single mode behaviour for large apertures. The modulation behaviour was not degraded by the PC. Simulations of type (II) and (III) PC-VCSELs, with the same parameters, have shown multimode operation and degraded modulation properties. Simulations of PC-VCSELs of type (III) with holes of d = 0.2 µm diameter and a = 0.4 µm lattice constant (d/a = 0.5) have shown improved modulation properties and enhanced single mode power for small apertures. In simulation, PC-VCSELs incorporating multiple PC-defects have shown order of magnitude increases in the single mode output power. However, the modulation properties of these VCSELs show degradation due to gain saturation and hopping of the optical modes localized within the PC defects.

Analysis of spatial hole burning and temperature effects in vertical-cavity surface-emitting lasers with internal photonic crystal waveguide

“…1 as proposed in previous research [11][12][13][14]. The upper metal contact is fabricated on top of the p-doped DBR and the bottom metal contact is fabricated on the n-doped substrate.…”

“…We assume that the active region of VCSELs is not etched, and therefore, the effects of PC holes on carrier diffusion and carrier loss are negligible [13]. Therefore, rate equations are valid for PC-VCSELs.…”

“…We compare this equation with G i 2 Imβ j , where Imβ j is an imaginary part of the propagation constant [15] to obtain the threshold current. Using the waveguide model introduced in Ivanov and Rorison [13] and Haghighat et al [14] and taking the scattering loss into account, we have the following:…”

“…Increasing the etching depth results in larger PC effect [9], so embedding a two-dimensional (2D) PC waveguide in the entire VCSEL has been proposed and analyzed [10][11][12][13][14]. This paper analyzes spatial hole burning (SHB) and the thermal effects on the structure on which a PC is made only in the cavity region.…”

Modelling investigations of DBRs and cavities with photonic crystal holes for application in VCSELs

“…The PC is usually introduced by etching air holes into the top DBR [4][5][6][7][8][9], thereby reducing the effective reflection coefficient of this DBR. The effect of optical losses due to etched holes has been addressed in a few recent works [14][15][16][17][18]. The reflectivity of the etched DBRs is crucial in understanding effects in PC-VCSELs and their modelling because it influences the photon lifetime and optical output power.…”