Fast photogalvanic response of a Bi_12SiO_20 crystal

Abstract

A photoelectric response of a Bi12SiO20 crystal grown in an argon atmosphere on a linearly polarized light (which is referred to as the linear photogalvanic effect) is reported for the first time in the nanosecond-time domain. Optimal geometry for detection of the photo-induced current concerning the orientation of the polarization state of the incident light in respect to the crystallographic axes of a sample was determined considering both the natural optical activity and light absorption of sillenite crystals. Spectral dependence of the photogalvanic current was measured in the visible part (410 - 610 nm) of the spectrum. Temporal shape of light-induced electric-current pulses observed at different experimental conditions is discussed. Obtained results are believed to show that sillenite crystals are very prospective for development of different ultra-fast optoelectronics devices.

Linear photogalvanic current excited in sillenite crystals by femtosecond laser pulses

“…The temporal shape of the observed electric pulses is similar to that observed in the BSO sample under illumination by nanosecond laser pulses [7]. The main physical reason of this similarity is capacitive electric coupling between the sample and the external circuit which includes electric cables and the oscilloscope.…”

“…The transfer function h(x) considering the spatial distribution of the LPG current caused by light absorption and optical rotation of the polarization plane was recently calculated for optically active sillenite crystals [7]. However, for a rough estimation of how the convolution influences the …”

“…1. As is known [7], in this geometry the photogalvanic current alternates its sign on changing the polarization state of the incident light to orthogonal. This specific feature was used for distinguishing the LPG effect from other photo-electric effects.…”

“…Experiments were carried out with a BTO sample cut from a crystal grown in normal atmosphere from nonstoichiometric (10 Bi 2 O 3 : 1 TiO 2 ) high-temperature solution and with the BSO sample used in the previous work [7]. Both samples have the same orientation shown in Fig.…”

“…Sillenite crystals, in particular Bi 12 SiO 20 (BSO) and Bi 12 TiO 20 (BTO), in which both photogalvanic effects were observed at the end of the 1970s [6], are undoubtedly good candidates. Recently, the linear photogalvanic effect (LPG) was observed in a BSO crystal (grown in argon atmosphere) under illumination by nanosecond laser pulses at wavelengths from 400 to 620 nm [7].…”