Stability and beam divergence of multimode lasers with internal variable lenses

Abstract

A resonator with an internal lens can be characterized by its equivalent g-parameters which give the regions of stability if the lens has variable focal length. However, other properties are not given by this equivalence and have to be investigated by means of the resonator matrix method. Beam diameter, divergence angle, number of transversal modes, positions of beam waists, stability, and the correlations of these parameters with position and focal length of the internal lens are discussed. Regions of low sensitivity to variations of the focal length are evaluated and compared with experimental results. For some special resonator configurations numerical results are presented.

A highly efficient 5kW peak power Nd:YAG laser with time-shared fiber optic beam delivery

“…The modified g à i -parameters and an equivalent resonator length L* with an internal variable lens are given by [7][8][9][10] …”

Laser diode pumped solid state lasers

“…We will express the fraction of energy extracted by TEX" Optical losses L in the resonator due to scattering, absorption or reflection further diminishes the laser output. It is 1 17 R • (16) where RI is the reflectivity of the output mirror. The efficiency factors discussed above can be grouped together…”

“…Almost all laser applications require a small beam divergence, ei [6][7][8][9][10][11][12][13][14][15][16][17][18] to obtain a small spot size at a large range, or a high power density at the focal plane of a bias. Therefore, the challenge in designing a stable resonator is to maximize low order mode power extraction.…”

Computer simulation of thermal focal length of laser crystal and thermally-near-unstable resonator

“…So it is the effective means by measuring the thermal focal length of gain medium to investigate the thermal effect. General experimental methods of measuring thermal focal length include: probe beam method [2][3][4], interference detecting method [5], unstable-resonator method [6][7], and transverse mode beat frequency [8]. But experimental steps are usually complex and time-consuming.…”