Ultrafast nonlinear effects in hydrogenated amorphous silicon wire waveguide.
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 (approximately 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.
Shoji
Yuya
Y
Network Photonics Research Center, National Institute of Advanced Industrial Science and Technology, 1-1-1Umezono, Tsukuba, Ibaraki 305-8568, Japan. y-shoji@aist.go.jp
Ogasawara
Takeshi
T
Kamei
Toshihiro
T
Sakakibara
Youichi
Y
Suda
Satoshi
S
Kintaka
Kenji
K
Kawashima
Hitoshi
H
Okano
Makoto
M
Hasama
Toshifumi
T
Ishikawa
Hiroshi
H
Mori
Masahiko
M
D004867:Equipment Design; D019544:Equipment Failure Analysis; D006859:Hydrogen / Q000737:chemistry*; D017711:Nonlinear Dynamics; D012031:Refractometry / Q000295:instrumentation*; D012825:Silicon / Q000737:chemistry*
D006859:Hydrogen; D012825:Silicon