Linear photogalvanic current excited in sillenite crystals by femtosecond laser pulses

Abstract

We observe electric pulses generated in sillenite crystals (Bi 12 SiO 20 and Bi 12 TiO 20 ) by 100-fs laser pulses at the wavelength of 400 nm (below the band gaps of both crystals). The peak value of the current pulses scales linearly with the intensity of laser pulses up to ∼45 GW/cm 2 . The direction of the induced current depends on the polarization state of the laser pulse. This polarization dependence and features of the current detection via charge accumulation at the sample electrodes allow us to conclude that the electric pulses are generated due to the linear photogalvanic effect.

Amplitude autocorrelation of femtosecond laser pulses using linear photogalvanic effect in sillenite crystals

“…2. The shape and duration of these pulses were the same as in experiments with illumination of the crystal by single laser pulse of known linear polarization [8]. If the delay between the laser pulses was larger than 100 fs electrical pulses of random shapes and random posi tions with amplitudes not exceeding 3.0 μA were observed.…”

“…The response of the crystal on the ultrashort light pulse was detected by measuring tran sient electric current which appears due to accumula tion of charges on the crystal electrodes [8]. A digital oscilloscope with bandwidth of 1 GHz was directly connected to the electrodes deposited on the opposite ( ) faces of the crystal.…”

“…The photogal vanic response of both crystals was observed in a wide range of wavelengths (0.4-0.6 μm) [7]. It should be emphasized that in contrast with the experiments with semiconductors in which the LPG current was induced due to band to band electron transitions [5,9,10], in sillenite crystals the impurity band transi tions were exploited [7,8].…”

“…In this scheme two orthogonally polarized laser pulses were used for the current excitation in a GaAs crystal and the response was measured via detection of generated THz radiation. Recently we demonstrated that the LPG current excited in sillenite crystals (Bi 12 SiO 20 and Bi 12 TiO 20 ) by laser pulses in nanosecond [7,8] and femtosecond [8] time domain can be directly mea sured by means of a digital oscilloscope in samples configured as a photoconductive cell. The photogal vanic response of both crystals was observed in a wide range of wavelengths (0.4-0.6 μm) [7].…”

Electron diffraction study of the sillenites Bi12SiO20, Bi25FeO39 and Bi25InO39: Evidence of short-range ordering of oxygen-vacancies in the trivalent sillenites

“…Sillenites are technologically-interesting due to their photo-refractive, [1][2][3][4] piezo-electric, 5 electro-optical, [6][7][8][9][10] and elasto-optical properties. 11,12 The last decade has witnessed an increase in the study of these compounds for photocatalysis and novel applications.…”