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

Abstract

We study the Gaussian laser transmission in lithium niobate crystal (LiNbO 3 ) 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.

Influences on oxidation voltage and holding time on poly(3-methylthiophene) film for electrochromic stability

“…[21][22][23][24][25][26][27][28][29][30][31][32][33][34] Combination of EC con-ducting polymers and carbon nanomaterials (graphene oxide and functionalized graphene) have exhibited good long-term optical stability, [35,36] which can be better improved by selecting a right electrolyte. [37][38][39][40][41][42] The electrolyte and electrode modification can enhance the operating voltages control efficiency to achieve satisfactory stability in EC process, with inappropriate voltage often causing irreversible EC reaction and undermining the EC material stability. [43] However, although many valuable studies have been explored about the above stability issues, the regulation of driving voltage has not been investigated in detail.…”