Numerical modeling of alkali vapor lasers

Abstract

Detailed numerical analyses are presented of a continuous wave (cw), single spatial mode alkali vapor laser pumped by a diffraction-limited Ti: Sapphire laser. These analyses provide insight into the operation of alkali vapor lasers to aid in the development of high power, diode laser pumped alkali vapor lasers. It is demonstrated that in the laser considered the laser spatial pattern is significantly changed after each pass through the gain medium, and the laser spatial pattern in steady state operation is also very different from that of the passive cavity mode. According to the calculation, lasing significantly improves the pump absorption efficiency and changes the absorbed pump distribution. The effect of varying the transverse size of the pumped region is also analyzed and an optimum pump beam waist radius is demonstrated. In addition, the shift of the pump beam waist location is also studied. The computation method and its convergence behavior are also described in detail.

Laser resonator modeling by field tracing: a flexible approach for fully vectorial transversal eigenmode calculation

“…The most common techniques, including the Gaussian beam propagation [10,11], the Collins integral [11,12,25], and the BPM [20,21], are based on the combination of the Fresnel integral [34] for free-space propagation with TEA [22] for the component modeling. In the round-trip operator notation this means…”

“…Therefore they used Kirchhoff's diffraction formula to propagate the field repeatedly along the resonator cavity. Sziklas and Siegman [16,17] already showed that replacing Kirchhoff's diffraction formula by a combination of the angular spectrum of plane waves (SPW) diffraction integral and the thin element approximation (TEA) leads to the beam propagation method (BPM) [18,19], which can be used to simulate resonator cavities containing inhomogeneous complex refractive index distributions, such as thermal lenses and active media [20,21]. However, this approach is also restricted due to the approximative character of TEA.…”