Thermal-birefringence-induced depolarization in Nd:YAG ceramics

Abstract

The thermal-birefringence effect in Nd(3+) -doped YAG ceramics has been investigated. The amount of depolarization induced by thermal birefringence in Nd:YAG ceramics is nearly the same as that in (111)-cut single crystals at the same Nd(3+) concentration. However, depolarization becomes larger as the Nd(3+) concentration increases, even at the same absorbed pump power.

Polarization Properties of Laser-Diode-Pumped Microchip Nd:YAG Ceramic Lasers

“…Therefore, polarization eigendirections are imposed by such a thermally induced crystal birefringence, and DPOs are considered to exceed unpolarized emissions, as expected in the case of small gain anisotropy. In micro-grained ceramic lasers, on the other hand, the averaging of thermal birefringence effect in Nd:YAG ceramics due to random distributions of crystal axes of grains reported by Shoji et al, 2002 is considered to become significant because of the extremely small grain sizes comparable to the lasing wavelength. Furthermore, in general, the thermally induced internal strain can be relaxed at grain boundaries in ceramics consisting of grains whose crystal axes are randomly distributed.…”

Numerical approach to temperature and thermal stress in direct-liquid-cooled Nd:YAG thin disk laser medium

“…Absorption coefficient α 18 cm -1 [7,8] Thermal conductivity of Nd:YAG λ 10 W/(m· K) [9] Coefficient of heat generation η 0.58 [8] Young modulus 3.1×10 10 kg/m 2 [10] Poisson ratio 0.30 [10] Linear expansion coefficient 7.8×10 -6 K -1 [10] Refractive index of liquid (water) nl 1.33…”

A silicon carbide face cooled ceramic Nd:YAG laser

“…Pump power, P was chosen to be 30W and to have an effective absorption coefficient, α = 6 cm -1 . The value of η h = 0.35 ± 0.05 was determined from the quantum defect of pumping Nd:YAG at 808 nm and lasing at 1064 nm and the radiative quantum efficiency for 4% Nd:YAG ceramic of η r = 0.25 ± 0.05 according to the formula [5],…”