TY - JOUR AU - Wathen, Jeremiah J. AU - Pagán, Vincent R. AU - Suess, Ryan J. AU - Wang, Ke-Yao AU - Foster, Amy C. AU - Murphy, Thomas E. TI - Non-instantaneous optical nonlinearity of an a-Si:H nanowire waveguide JO - Optics Express J2 - Opt. Express VL - 22 IS - 19 SP - 22730 EP - 22742 PY - 2014 DO - 10.1364/OE.22.022730 AB - 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. UR - http://www.opticsexpress.org/abstract.cfm?URI=oe-22-19-22730 KW - Nonlinear optical materials Nonlinear optics, devices Nonlinear optics, integrated optics Optical nonlinearities of condensed matter Nonlinear optical devices Waveguides LB - Wathen_OE_22_22730_2014 ER -