Analytical model for thermal lensing and spherical aberration in diode side-pumped Nd:YAG laser rod having Gaussian pump profile

Abstract

In this paper, according to the temperature and strain distribution obtained by considering the Gaussian pump profile and dependence of physical properties on temperature, we derive an analytical model for refractive index variations of the diode side-pumped Nd:YAG laser rod. Then we evaluate this model by numerical solution and our maximum relative errors are 5% and 10% for variations caused by thermo-optical and thermo-mechanical effects; respectively. Finally, we present an analytical model for calculating the focal length of the thermal lens and spherical aberration. This model is evaluated by experimental results.

Pump pulse characteristics of quasi-continuous-wave diode-side-pumped Nd:YAG laser

“…Compared with diode-end-pumped lasers with the characteristics of the high absorption, the excellent overlap between pump volume and laser mode, and the high pump densities, the diode-side-pumped lasers have the advantages of compactness, high reliability and flexibility, and easily integrated. [16] Moreover, side-pumped device can offer simplicity by eliminating coupling optics while providing the potential for scaling the solid-state lasers to a much higher power level. The cross section schematic configuration of homemade laser diode (LD) side-pumped Nd:YAG laser module is illustrated in Fig.…”

Modeling of thermal lensing in a [1 1 1]-cut Nd:YAG rod with temperature-dependent parameters and different pumping profiles

“…. The experimental data analyzed recently in [33] is well fitted by ξ = 1.0 in the temperature range between 160 and 500 K. Sometimes, the coefficient ξ = 0.7 is used in calculations [16,21,22]. Additionally, different values of the coefficient of thermal conductivity k 0 at the reference temperature T r were used previously.…”

“…was used in [16,21,22] instead of ( ) α Σ r . Therefore, equations ( 15) are deliberately presented in the form, which is close to equation (B.7) in [16] and to equations ( 23)-( 25) in [21].…”

“…One of the main causes for the occurrence of thermal aberrations and the enhancement of thermal lensing is nonuniform radial pump distribution [1][2][3][4][5][6]. However, the temper ature dependence of the thermal, mechanical and optical parameters of AE is also a very important factor influencing the values of optical power and thermal aberrations [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23].…”

“…The temperature dependence of the thermal conductivity and of other parameters of the YAG is also very important for a consistent description of thermal lensing because it causes the radial temperature distribution to have higher nonparabolic terms, even for homogeneous heat loading in the AE [7][8][9][15][16][17][18][19][20][21][22][23]. It has been shown [8] that the spherical aberration induced due to the temperature-dependent thermal conductivity of AE can be compensated by a proper choice of parabolic pumping distribution.…”