title: Photorefractive effect in undoped aluminum nitride.
abstract: We report our observation of the photorefractive effect in undoped aluminum nitride. We measured the coupling constant and the formation rate as a function of pump intensity at a wavelength of 405 nm in a two-wave mixing experiment. The photorefractive gain coefficient was 0.47 cm(-1) at I = 6.9 W/cm(2), and the actual saturated value was probably larger than this. The time constant was 59 ms at I = 1.0 W/cm(2). In addition to a refractive index grating, an absorption grating was also formed, which is attributed mainly to an ionized trap density modulation process.
authors.affiliation: Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-Ku, Tokyo 153-8505, Japan. nagai@iis.u-tokyo.ac.jp
authors.forename: Toru
authors.initials: T
authors.lastname: Nagai
authors.forename: Ryushi
authors.initials: R
authors.lastname: Fujimura
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Shimura
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kuroda