Non-instantaneous optical nonlinearity of an a-Si:H nanowire waveguide
Published/Posted: September 15, 2014
Authors: Wathen, J. J.; Pagán, V. R.; Suess, R. J.; Wang, K.-Y.; Foster, A. C.; Murphy, T. E.
DOI: 10.1364/OE.22.022730Abstract: We use pump-probe spectroscopy and continuous wave cross-phase and cross-amplitude modulation measurements to study the optical nonlinearity of a hydrogenated amorphous silicon (a-Si:H) nanowire waveguide, and we compare the results to those of a crystalline silicon waveguide of similar dimensions. The a-Si:H nanowire shows essentially zero instantaneous two-photon absorption, but it displays a strong, long-lived non-instantaneous nonlinearity that is both absorptive and refractive. Power scaling measurements show that this non-instantaneous nonlinearity in a-Si:H scales as a third-order nonlinearity, and the refractive component possesses the opposite sign to that expected for free-carrier dispersion.
J. J. Wathen, V. R. Pagán, R. J. Suess, K.-Y. Wang, A. C. Foster and T. E. Murphy, "Non-instantaneous optical nonlinearity of an a-Si:H nanowire waveguide", Opt. Express 22(19) 22730-22742 (2014)
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