Abstract
For a long time that optical damage was renamed as photorefraction, here we find that the optical damage resistance and photorefraction can be simultaneously enhanced in MgO and Bi2O3 co-doped LiNbO3 (LN:Bi,Mg). The photorefractive response time of LN:Bi,Mg was shortened to 170 ms while the photorefractive sensitivity reached up to 21 cm2/J. Meanwhile, LN:Bi,Mg crystals could withstand a light intensity higher than 106 W/cm2 without apparent optical damage. Our experimental results indicate that photorefraction doesn’t equal to optical damage. The underground mechanism was analyzed and attributed to that diffusion dominates the transport process of charge carriers, that is to say photorefraction causes only slight optical damage under diffusion mechanism, which is very important for the practical applications of photorefractive crystals, such as in holographic storage, integrated optics and 3D display.
Highlights
For a long time that optical damage was renamed as photorefraction, here we find that the optical damage resistance and photorefraction can be simultaneously enhanced in MgO and Bi2O3 co-doped LiNbO3 (LN:Bi,Mg)
The photorefractive response time constant tr and the saturated diffraction efficiency ηs are described by the function η = sin2(πdΔ n/λcosθ), where λ of is tηhte=freηes-(s1pa−ceew−ta/vtre)l2e.nTghteh,cdhaisngtheeolfetnhgethreofrfagcrtaitvienignwdeitxhΔin nthies calculated from sample, and θ is ltihgehBt irnatgegnasnitgylae.nTdhleispthhoetothreicfrkancetsivseosfecnrsyisttiavlitpylaistedse.fFinoerddeatsaSil=exp((e∂rimηe)n/ta∂lts)et=tu0p/sIla,nwdhperaeraImisettheer total recording definition, one can see ref. 21
Compared with the famous iron doped LN (LN:Fe)[22], the response time of LN:Bi,Mg is more than two orders of magnitude shorter while the diffraction efficiency is only several times lower, so the photorefractive sensitivity was greatly enhanced. These results indicate that LN:Bi,Mg crystals are more suitable for the practical applications in holographic processing
Summary
For a long time that optical damage was renamed as photorefraction, here we find that the optical damage resistance and photorefraction can be simultaneously enhanced in MgO and Bi2O3 co-doped LiNbO3 (LN:Bi,Mg). Optically-induced refractive index inhomogeneities were firstly observed in LiNbO3 (LN) and LiTaO31 This effect, interesting in its own right, poses serious limitations in the use of these crystals in nonlinear devices requiring high light intensity, such as frequency doubler, optical parametric oscillator, Q-switcher, and integrated optics[2,3,4,5,6], so later was called as optical damage. This same effect can be used to advantage to form a holographic recording in the applications where a material gives refractive index change directly upon exposure, so it was renamed as photorefraction (PR), and LN was found as an extremely interesting holographic media[7]. It was found that LN:Bi,Mg crystals have simultaneously enhanced PR with high optical damage resistance, and the mechanism about this phenomenon was discussed
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