Schematic of the band gap (refractive index profile), mode intensity, and waveguide layer carrier density distribution (at , , and ) in a broadened [ (a)] and nonbroadened [ (b)], symmetric (dashed) and asymmetric (solid) waveguide structures. The refractive indices used correspond (Ref. 11) to an InGaAsP waveguide, at , with material band gaps of 1.113 eV (waveguide), 1.35 eV ( cladding), and 1.184 eV (asymmetric waveguide cladding).
Dependence of the free-carrier absorption in the waveguide core region on the active layer position for the same waveguide structures and current as those shown in Fig. 1. Dashed: symmetric waveguides; solid: asymmetric waveguides. The arrows indicate the positions maximizing the active layer overlap.
Confinement factors (overlap coefficients) for the same structures as in Figs. 1 and 2 (a) cladding , (b) cladding , (c) active layer and waveguide core . Dashed: symmetric waveguides; solid: asymmetric waveguides. Shown on the right axes of (a) and (b) are cladding losses for cladding doping levels and . (c) is calculated using an active layer thickness of 120 Å.
Output efficiency for a broad symmetric (dashed line) and nonbroadened asymmetric (solid line) waveguide structures. The structure parameters are as in Figs. 1–3; outcoupling loss (cavity length , reflectances and ).
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