中国物理B ›› 2015, Vol. 24 ›› Issue (9): 94203-094203.doi: 10.1088/1674-1056/24/9/094203

• ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS • 上一篇    下一篇

Coupled thermal-optic effects and electrical modulation mechanism of birefringence crystal with Gaussian laser incidence

周吉, 贺志宏, 马宇, 董士奎   

  1. School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China
  • 收稿日期:2014-12-09 修回日期:2015-03-21 出版日期:2015-09-05 发布日期:2015-09-05
  • 基金资助:

    Project supported by the National Natural Science Foundation of China (Grant No. 51176039).

Coupled thermal-optic effects and electrical modulation mechanism of birefringence crystal with Gaussian laser incidence

Zhou Ji (周吉), He Zhi-Hong (贺志宏), Ma Yu (马宇), Dong Shi-Kui (董士奎)   

  1. School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China
  • Received:2014-12-09 Revised:2015-03-21 Online:2015-09-05 Published:2015-09-05
  • Contact: Zhou Ji, Dong Shi-Kui E-mail:zhouji174@163.com;dongsk@hit.edu.cn
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Grant No. 51176039).

摘要:

We study the Gaussian laser transmission in lithium niobate crystal (LiNbO3) by using the finite element method to solve the electromagnetic field's frequency domain equation and energy equation. The heat generated is identified by calculating the transmission loss of the electromagnetic wave in the birefringence crystal, and the calculated value of the heat generated is substituted into the energy equation. The electromagnetic wave's energy losses induced by its multiple refractions and reflections along with the resulting physical property changes of the lithium niobate crystal are considered. Influences of ambient temperature and heat transfer coefficient on refraction and walk-off angles of O-ray and E-ray in the cases of different incident powers and crystal thicknesses are analyzed. The E-ray electrical modulation instances, in which the polarized light waveform is adjusted to the rated condition via an applied electrical field in the cases of different ambient temperatures and heat transfer coefficients, are provided to conclude that there is a correlation between ambient temperature and applied electrical field intensity and a correlation between surface heat transfer coefficient and applied electrical field intensity. The applicable electrical modulation ranges without crystal breakdown are proposed. The study shows that the electrical field-adjustable heat transfer coefficient range becomes narrow as the incident power decreases and wide as the crystal thickness increases. In addition, it is pointed out that controlling the ambient temperature is easier than controlling the heat transfer coefficient. The results of the present study can be used as a quantitative theoretical basis for removing the adverse effects induced by thermal deposition due to linear laser absorption in the crystal, such as depolarization or wave front distortion, and indicate the feasibility of adjusting the refractive index in the window area by changing the heat transfer boundary conditions in a wide-spectrum laser.

关键词: birefringence, electro-optic modulators, thermo-optic effects

Abstract:

We study the Gaussian laser transmission in lithium niobate crystal (LiNbO3) by using the finite element method to solve the electromagnetic field's frequency domain equation and energy equation. The heat generated is identified by calculating the transmission loss of the electromagnetic wave in the birefringence crystal, and the calculated value of the heat generated is substituted into the energy equation. The electromagnetic wave's energy losses induced by its multiple refractions and reflections along with the resulting physical property changes of the lithium niobate crystal are considered. Influences of ambient temperature and heat transfer coefficient on refraction and walk-off angles of O-ray and E-ray in the cases of different incident powers and crystal thicknesses are analyzed. The E-ray electrical modulation instances, in which the polarized light waveform is adjusted to the rated condition via an applied electrical field in the cases of different ambient temperatures and heat transfer coefficients, are provided to conclude that there is a correlation between ambient temperature and applied electrical field intensity and a correlation between surface heat transfer coefficient and applied electrical field intensity. The applicable electrical modulation ranges without crystal breakdown are proposed. The study shows that the electrical field-adjustable heat transfer coefficient range becomes narrow as the incident power decreases and wide as the crystal thickness increases. In addition, it is pointed out that controlling the ambient temperature is easier than controlling the heat transfer coefficient. The results of the present study can be used as a quantitative theoretical basis for removing the adverse effects induced by thermal deposition due to linear laser absorption in the crystal, such as depolarization or wave front distortion, and indicate the feasibility of adjusting the refractive index in the window area by changing the heat transfer boundary conditions in a wide-spectrum laser.

Key words: birefringence, electro-optic modulators, thermo-optic effects

中图分类号:  (Birefringence)

  • 42.25.Lc
78.20.Jq (Electro-optical effects) 78.20.nb (Photothermal effects) 42.79.Hp (Optical processors, correlators, and modulators)