Third-order nonlinearities of Bi12GeO20 crystal measured by nanosecond radiation

Abstract

Articles you may be interested inLarge femtosecond third-order optical nonlinearity of Bi3.15Nd0.85Ti3O12 ferroelectric thin films Negative nonlinear refraction is observed in the photorefractive crystal Bi 12 GeO 20 ͑BGO͒ using 7-ns, 532-nm pulsed radiation. The nonlinear refractive index of BGO is measured to be ␥ = −3.8 ϫ 10 −13 cm 2 W −1 using the z-scan technique. The self-defocusing of nanosecond pulses is attributed to the appearance of free carriers generated from defects, donors, and interband transitions. The nonlinear losses caused by two-photon absorption and self-scattering from dynamic grating are discussed. The nonlinear absorption coefficient is measured to be ␤ = 3.8ϫ 10 −8 cm W −1 . Moreover, a variation of ␥ and ␤ with intensity is observed. The comparison with self-focusing and two-photon absorption previously measured using 55-ps pulses is discussed.

Influence of femtosecond pulsed laser irradiation on bismuth germanium oxide single crystal properties

“…The five oxygen atoms compose an incomplete octahedral arrangement and the remaining two oxygen atoms are electrostatically coordinated on a side of E [1,3]. Due to its photoconductivity, photochromism, photorefractivity, piezoelectricity, as well as to electro-optic and magneto-optic effects it supports [7,8], Bi 12 GeO 20 is suitable for a broad range of applications and devices such as optical limiting, holography, spatial light modulation, optical phase conjugation, optical memories, fiber optic sensors, Pockels cells [8][9][10][11][12]. The properties of non-doped as well as doped Bi 12 GeO 20 were investigated and reported in a number of studies, for example in [13][14][15][16][17][18][19][20][21].…”

“…The properties of non-doped as well as doped Bi 12 GeO 20 were investigated and reported in a number of studies, for example in [13][14][15][16][17][18][19][20][21]. Characteristics of Bi 12 GeO 20 single crystals after exposure to thermal treatment [16][17][18][19]22], to beams of electrons [23], uranium ions [24], fluorine ions [15], g-ray [19] or light [9,18,22,[25][26][27][28] were investigated. Nonlinear properties of Bi 12 GeO 20 crystals were measured with pulsed laser beams in the nanosecond range in [9], whereas in [26][27][28] BGO crystals were irradiated by picosecond laser pulses.…”

“…Characteristics of Bi 12 GeO 20 single crystals after exposure to thermal treatment [16][17][18][19]22], to beams of electrons [23], uranium ions [24], fluorine ions [15], g-ray [19] or light [9,18,22,[25][26][27][28] were investigated. Nonlinear properties of Bi 12 GeO 20 crystals were measured with pulsed laser beams in the nanosecond range in [9], whereas in [26][27][28] BGO crystals were irradiated by picosecond laser pulses. Transmission, absorption [16,19], and Raman spectra [19] were found to be significantly influenced by doping and annealing.…”

Optical properties of crystalline and ion-beam amorphized Bi12GeO20: Relevance for waveguide applications

“…It consists of the Bi 3+ ions coordinated heptahedrally by oxygen [2]. It has high electro-optic coefficients (3.3 pm/V), making it useful in nonlinear optics, for building Pockels cells, as well as for the fabrication of photorefractive devices with applications in optical limiting, spatial light modulation and online holographic recording [3,4]. However, it is striking that so far its optical properties have been determined only for a limited region of the visible spectrum [5,6].…”

Characterisation of optical waveguides in BGO crystals fabricated by N⁺ ion implantation

“…Thanks to its very good radiation length, short decay time, emission efficiency and response linearity, it is widely used as scintillator material for radiation detectors in high-energy physics and in medical diagnostic systems such as PET (positron emission tomography) [1]. It also has a relatively high large electro optic coefficient (3 .3 pm/V) and second and third order non linear properties have been reported [2], which make this material also suitable for many applications in the field of opto-electronic devices.The possibility of fabricating guided-wave structures in this material is therefore of great interest, since it can allow the development of miniaturised radiation detectors for PET or, exploiting the optical confinement and long interaction length offered by integrated optics, optical devices based on nonlinear effects.Among the available waveguide fabrication processes, ion implantation has been proved as a universal technique in order to produce integrated optical guiding structures in many glassy [3] and crystalline materials thanks to its high versatility and good controllability, so that the fabrication of optical waveguides in BOO crystals by He+ ion implantation has indeed already been reported [4].In this paper we describe the fabrication and characterisation of slab optical waveguides in eulytine BOO crystal obtained by N+ high energy ion implantation. Utilising heavier ions for the implantation process has been proved to produce the same refractive index change at smaller doses than when light ions such as He + are used [5] and we therefore intended to assess the effects of N+ ions implantation in order to demonstrate the feasibility of this process and optimise it with the future aim of developing waveguide based optical devices.…”