光折变光栅在超短脉冲光照射下衍射的研究

Study of Diffraction Effect of a Photorefractive Volume Holography UnderUltrashort Pulsed-Laser Beam Illumination

利用Kogelnik单色光在体光栅中衍射效率公式推导出超短脉冲光读出稳态光折变体光栅时的衍射光频谱表达式,并在此基础上导出了脉冲光读出时的总衍射光强及总光强衍射效率·研究发现衍射光的频谱分布、总光强及衍射效率与光栅周期Λ、光栅厚度d和读出光脉冲宽度Δτ有密切的关系·通过调整这些参量,光折变光栅可以对入射的超短脉冲光实现不同程度的滤波作用·该结论可用于超短脉冲的整形研究·

Using Kogelnik＇s equation of diffraction efficiency of monochrome light from thick hologram gratings, an expression for calculating the diffraction intensity spectrum of a photorefractive volume hologram under ultrashort-pulsed light illumination was derived. Then total diffraction intensity and diffraction efficiency were deduced. Study showsd that the diffraction intensity spectrum, total diffraction intensity and diffraction efficiency were in close connection with grating spacing ∧, grating thickness d, and readout pulse width △τ. Through modulating these parameters, different extent of filtering for the incident ultrashort pulse can be realized. The results can be utilized to study the shaping of ultrashort pulse.