| Autor: |
Bissinger, Jochen, Ruhstorfer, Daniel, Stettner, Thomas, Koblmüller, Gregor, Finley, Jonathan J. |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; 6/28/2019, Vol. 125 Issue 24, pN.PAG-N.PAG, 8p, 1 Diagram, 3 Graphs |
| Abstrakt: |
The recent integration of III-V semiconductor nanowire (NW) lasers on silicon waveguides marked a key step toward their usage as coherent light sources for future silicon photonics applications. However, the low index contrast between III-V semiconductors and silicon results in a weak modal reflectivity, calling for improved design structures that enable both low-threshold lasing and good in-coupling efficiency into waveguides. Here, we perform numerical simulations to explore how the alternating refractive index of a silicon waveguide with a thin SiO2 interlayer can be used to significantly improve the reflectivity at the III-V–silicon interface to values of up to 83%. We further investigate the frequency dependencies of the end-facet reflectivity and in-coupling efficiency as a function of the nanowire and waveguide dimensions. Our results are kept general by the normalization to the nanowire radius R and show for a waveguide width of 2.75⋅ R a maximum coupling efficiency of 50%. Variations in waveguide height or SiO2 interlayer thickness by ± 0.1 ⋅ R increase the coupling efficiency by a factor of 2, with little effect on the end-facet reflectivity. Ultimately, a prototypical NW-laser structure consisting of a 1.3-μm emitting InGaAs MQW active region in a core-multishell structure was simulated, showing an optimized low-threshold gain of <500 cm−1 for a TE01 mode with a coupling efficiency of ∼13%. By simplified approximations, we illustrate that these analyses can be adapted to a variety of material systems and serve as guidelines in the construction of optimized nanowire lasers on silicon-on-insulator waveguides for future on-chip optical interconnects. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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