Inside-pumped Nd:YAG tube laser

Abstract

A novel type of solid-state laser with a tubular active element made of Nd:YAG is presented. Using the tube geometry, one can achieve higher efficiency and higher output power per laser crystal than by using a rod or slab geometry. Our tube laser is pumped from the inside by four flash lamps. The slope efficiency of 9% and the total efficiency of 7.5% at as much as 400 W of output power are, to our knowledge, the highest values reported for flash-lamp-pumped Nd:YAG lasers. At 15 kW, 75% of the maximum available pumping power, the output power is 1000 W. Thermal lensing is five times lower than for an equivalent rod laser.

Array of unstable resonators for a laser with an annular gain geometry

“…The number of resonators N to cover the whole cross-section of the active medium is equal to the first integer greater than π φ 2 / . For example, a group of four resonators, with φ π = /2 each, can be used with the Nd:YAG tube with the outer diameter of 53 mm and the inner diameter of 35 mm, described in [8].…”

Coupling efficiencies and mode discrimination in coaxial waveguide laser resonators

“…where R is the radius of curvature of the toric mirror, A and B are the outer and inner radii of the integral area on the mirror and r m is the central radius of the coaxial waveguide r m = (a + b)/2. When deriving (10) the integral expression (11) for Bessel function has been used:…”

“…where the highly oscillatory term has been dropped due to its much smaller contribution to the integral [7][8]. For d = R, the Fourier optical transform gives [11]…”

<title>Simple annular resonators with toric and helical mirrors</title>

“…3D-calculations are necessary because the resonators do not exhibit rotational symmetry. A Fourier expansion of the transverse electric field is used E(r, ,z) = l:1 1 (r, z) e1 (2) Since the beams are azimuthally guided high azimuthal mode orders 1 are involved. Proper truncation of the sum is necessary for numerical calculations and the induced error has to be monitored.…”

“…These advantages include highly efficient diffusion cooling [1], efficient laser excitation by internal pumping sources [2] or great gain volumes with short axial dimensions.…”