Variation of the band structure in DKDP crystal excited by intense sub-picosecond laser pulses

Xiaocong Peng,Yuanan Zhao,Zhen Cao,Yueliang Wang,Guohang Hu,Jianda Shao

doi:10.1017/hpl.2018.35

Abstract

The nonlinear absorption (NLA) properties of potassium dideuterium phosphate crystals at 515 nm under different excitation laser intensities are investigated with the Z-scan technique. Two critical intensities are highlighted: the critical intensity for exciting the NLA and the critical intensity of the multiphoton absorption mechanism transition. Experimental results indicate the existence of defect states located in the band gap, which can be manipulated by varying laser intensity. A model based on the change of multiphoton absorption mechanism induced by the transformation of defect species is proposed to interpret the experiments. Modeling results are in good agreement with the experiment data.

Highlights

Potassium dihydrogen phosphate (KDP) and its deuterated analog, potassium dideuterium phosphate (DKDP) crystals are remarkable multifunctional crystal materials, which are widely applied in fields such as frequency conversion, electro-optic modulation and optical rapid switches[1]
A model based on the change of multiphoton absorption mechanism induced by the transformation of defect species is proposed to interpret the experimental data
To confirm the above-mentioned analysis and further interpret the experimental data, we propose a model based on the change of multiphoton absorption mechanism induced by the transformation of defect species

Summary

Introduction

Potassium dihydrogen phosphate (KDP) and its deuterated analog, potassium dideuterium phosphate (DKDP) crystals are remarkable multifunctional crystal materials, which are widely applied in fields such as frequency conversion, electro-optic modulation and optical rapid switches[1]. Several theoretical and experimental studies have suggested that point defects in bulk crystals can provide states in the band gap[8,9,10,11] and assist in the multiphoton absorption process[12,13,14,15,16]. Duchateau et al developed a model with two defect states in the band gap, which reduced the order of the multiphoton process to interpret the physical mechanisms of two relaxation dynamics in the KDP/DKDP crystals at 800 nm[14]. The NLA properties of DKDP crystals have been characterized by some authors with the picosecond Z-scan method[17, 18] These experiments were performed under low laser irradiation intensities. A model based on the change of multiphoton absorption mechanism induced by the transformation of defect species is proposed to interpret the experimental data

Methods

Results

Conclusion