Ultrafast nonlinear effects in hydrogenated amorphous silicon wire waveguide

作者：Shoji Yuya^*; Ogasawara Takeshi; Kamei Toshihiro; Sakakibara Youichi; Suda Satoshi; Kintaka Kenji; Kawashima Hitoshi; Okano Makoto; Hasama Toshifumi; Ishikawa Hiroshi; Mori Masahiko

来源：Optics Express, 2010, 18(6): 5668-5673.

DOI：10.1364/OE.18.005668

We, for the first time, present the ultrafast optical nonlinear response of a hydrogenated amorphous silicon (a-Si:H) wire waveguide using femtosecond pulses. We show cross-phase and cross-absorption modulations measured using the heterodyne pump-probe method and estimate the optical Kerr coefficient and two-photon absorption coefficient for the amorphous silicon waveguide. The pumping energy of 0.8 eV is slightly lower than that required to achieve two-photon excitation at the band gap of a-Si:H (similar to 1.7 eV). An ultrafast response of less than 100 fs is observed, which indicates that the free-carrier effect is suppressed by the localized states in the band gap.

• 出版日期2010-3-15