Electroabsorption in gated GaAs nanophotonic waveguides

Wang, Y. and Uppu, R. and Zhou, X. and Papon, C. and Scholz, S. and Wieck, A.D. and Ludwig, Ar. and Lodahl, P. and Midolo, L.

Volume: 118 Pages:
DOI: 10.1063/5.0039373
Published: 2021

We report on the analysis of electroabsorption in thin GaAs/Al0.3Ga0.7As nanophotonic waveguides with an embedded p-i-n junction. By measuring the transmission through waveguides of different lengths, we derive the propagation loss as a function of electric field, wavelength, and temperature. The results are in good agreement with the Franz-Keldysh model of electroabsorption extending over 200 meV below the GaAs bandgap, i.e., in the wavelength range of 910-970 nm. We find a pronounced residual absorption in forward bias, which we attribute to Fermi-level pinning at the waveguide surface, producing over 20 dB/mm loss at room temperature. These results are essential for understanding the origin of loss in nanophotonic devices operating in the emission range of self-assembled InAs semiconductor quantum dots toward the realization of scalable quantum photonic integrated circuits. © 2021 Author(s).

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