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arXiv · 1303.0496

Enhancement of 3rd-harmonics generation during ultrashort pulse diffraction in multi-layer volume-grating

Tan Yizhou·Yang Yisheng·Liao Jiali·Zhang Ming
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Abstract

Successful phase-matching methods for Third Harmonics Generation (THG) include phase-matching in birefringent crystal and quasi-phase-matching (QPM) in crystal with periodically poled domains. However, these methods are not feasible in some isotropic materials (e.g. fused silica and photosensitive silicate glass). It was known that volume-grating in isotropic materials can independently generate frequency-converted waves. One of disadvantages of single-layer volume-grating is that the brightness of harmonic emission can not be enhanced by increasing the grating thickness. In this paper, a THG device with stratified sub-gratings was designed to enhance THG in isotropic materials: several sub-gratings were arranged parallel, and the grating-figures misalignment between neighboring sub-gratings was pre-fabricated. In terms of extension of interaction length in THG, our multi-layer sub-grating is formally equivalent to the multi-layer periodically poled crystal (e.g. lithium niobate) in conventional QPM approach. According to the calculation results, the N-layer (N >2) can, in principle, generate TH output intensity of N*N times stronger than single-layer volume-grating does, also compared to N times stronger than N-layer without figures-misalignment. The effect of random fabrication error in grating thickness on normalized conversion efficiency was discussed.

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Tan Yizhou, Yang Yisheng, Liao Jiali, Zhang Ming. 2013-07-23. Enhancement of 3rd-harmonics generation during ultrashort pulse diffraction in multi-layer volume-grating. https://arxiv.org/abs/1303.0496

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