Thermally-induced lens in an end-pumped cesium laser

Diode-pumped alkali lasers (DPALs) have attracted a lot of attentions in the recent years for their high Stocks efficiency, good beam quality, compact size and near-infrared emission wavelengths. In this study, we analyze the thermally-induced lens in an end-pumped cesium cell by using the evaluated parameters such as the population density distribution, the transition rates of pump photon absorption, and the transition rates of laser photon emission, which had been obtained in our previous study. After dividing a cylindrical vapor cell into many cylindrical annuli, we calculate the refractive index n and the thermal-optic coefficient dn/dT in every annule. And then, we carry out the ray-trace to describe the propagation of an incident ray inside the vapor cell. Assuming that the incident plane-wave has a flat-top distribution, the intensity distribution of the outputted beam can be deduced. We adopted the second-moment calculation to evaluate the beam size after the ray passes through a pumped cell. Finally, the effective focal length of a thermally-induced lens was obtained for the end-pumped laser configuration. The research will be helpful to improve the beam quality of a DPAL.

[1]  Xiaojun Xu,et al.  Modeling, numerical approach, and power scaling of alkali vapor lasers in side-pumped configuration with flowing medium , 2011 .

[2]  Gordon D. Hager,et al.  A study of collisional quenching and radiation-trapping kinetics for Rb(5p) in the presence of methane and ethane using time-resolved fluorescence , 2009 .

[3]  Glen P. Perram,et al.  Investigation of radial temperature gradients in diode pumped alkali lasers using tunable diode laser absorption spectroscopy , 2012, LASE.

[4]  Bailiang Pan,et al.  Thermal Effects in High-Power Double Diode-End-Pumped Cs Vapor Lasers , 2012, IEEE Journal of Quantum Electronics.

[5]  Walter Koechner,et al.  Solid-State Laser Engineering , 1976 .

[6]  Karol Waichman,et al.  Computational fluid dynamics modeling of subsonic flowing-gas diode-pumped alkali lasers: comparison with semi-analytical model calculations and with experimental results , 2014 .

[7]  Randall J. Knize.  Diode Pumped Alkali Laser for Defense , 2016 .

[8]  Wei Zhang,et al.  Algorithm for evaluation of temperature distribution of a vapor cell in a diode-pumped alkali laser system: part I. , 2014, Optics express.

[9]  Koichi Inoue,et al.  A MOPA with double-end pumped configuration using total internal reflection , 2010 .

[10]  V Keith Kanz,et al.  Resonance transition 795-nm rubidium laser. , 2003, Optics letters.

[11]  Gordon D. Hager,et al.  Collisional quenching and radiation trapping kinetics for Rb(5p) in the presence of ethane , 2008, High-Power Laser Ablation.

[12]  Herwig Kogelnik,et al.  Imaging of optical modes — resonators with internal lenses , 1965 .

[13]  Boris V Zhdanov,et al.  Rubidium vapor laser pumped by two laser diode arrays. , 2008, Optics letters.

[14]  Boris V. Zhdanov,et al.  Multiple laser diode array pumped Cs laser with 48W output power , 2008 .

[15]  Wei Zhang,et al.  Theoretical study on temperature features of a sealed cesium vapor cell pumped by laser diodes. , 2014, Applied optics.

[16]  Boris D. Barmashenko,et al.  Detailed analysis of kinetic and fluid dynamic processes in diode-pumped alkali lasers , 2013 .

[17]  V. K. Kanz,et al.  End-pumped continuous-wave alkali vapor lasers: experiment, model, and power scaling , 2004 .

[18]  G. Perram,et al.  A three-level analytic model for alkali metal vapor lasers: part I. Narrowband optical pumping , 2010 .

[19]  Boris V. Zhdanov,et al.  Optically pumped potassium laser , 2007 .

[20]  Hirofumi Miyajima,et al.  Cesium vapor laser pumped by a volume-Bragg-grating coupled quasi-continuous-wave laser-diode array , 2006 .

[21]  Qi Zhu,et al.  Analysis of temperature distributions in diode-pumped alkali vapor lasers , 2010 .

[22]  Jian Jiao,et al.  Thermal Effects of High-Power Side-Pumped Alkali Vapor Lasers and the Compensation Method , 2014, IEEE Journal of Quantum Electronics.