Justin L. Blows

Heat generation in Nd:YVO 4 with and without laser action

We present quantitative interferometric measurements of thermal lensing in a diode-pumped Nd:YVO/sub 4/ crystal with and without laser action. The thermal loading increased by two times when laser action was inhibited. The thermal loading was strongly dependent on upper laser-level loss mechanisms (e.g. nonradiative decay, quenching, and Auger recombination).

Thermal lensing measurements in line-focus end-pumped neodymium yttrium aluminium garnet using holographic lateral shearing interferometry

Thermal lensing in compact neodymium yttrium aluminium garnet slabs and rods end pumped with a beam brought to a line focus has been measured using holographic lateral shearing interferometry. This powerful technique enabled us to directly measure thermal lenses with focal lengths in the range 0.02–12 m with an accuracy of 12% and good spatial resolution. It was found that the line focused pump beam resulted in severe astigmatic thermal lensing. The measured thermal lens strongly deviated from the ideal parabolic profile along both axes, introducing an important additional consideration for laser-diode end-pumped laser resonator design. The degree of longitudinal heat flow was found to strongly influence thermal lens power. It is anticipated that results obtained from the measurement technique presented here will enable optimal design of high-power end-pumped solid-state laser cavities.

Mode characteristics of twisted resonators composed of two cylindrical mirrors.

We examine the optical resonator composed of two astigmatic elements, in a twisted configuration. These cavities have mode cross-sections with principal axes that rotate on propagation. Explicit cavity mode equations are derived for the case of identical mirrors. Such a resonator is appropriate for a solid-state laser that is end-pumped with the output of a laser-diode array brought to a line focus. We present a simple analysis of the significance of rotational misalignment, which effects the pump-to-mode power coupling, beam quality, and cavity stability.

Cavity modes in diode-array end-pumped planar lasers with aberrated thermal lenses

The effects of an aberrated thermal lens on the cavity mode profile and on diffraction losses are investigated numerically for end-pumped solid-state lasers. Planar crystals are considered because they naturally compliment the line-like beam output from diode arrays in addition to offering good thermal management. The aberrations result in a non-Gaussian cavity mode that is significantly broader and thus can cause an increase in the cavity losses. Planar laser geometries can give excellent beam quality. This is a strong function of the degree of the thermal lensing. Thermal lensing must be used to control the overall resonator stability and mode size but diffraction effects, in addition, shape the mode strongly so as to give surprisingly good beam quality for a particular range of thermal lenses.

A simple, thermally-stabilised, diode end-pumped, planar Nd:YAG laser

Abstract We report a simple planar Nd:YAG laser design that produces over 3 W of TEM 00 output at 1.064 μm, end-pumped by a single laser-diode array. The diode output is brought to a line focus within the laser crystal, producing a planar gain volume. The laser cavity incorporates a single cylindrical lens providing a highly elliptical mode and giving good pump and cavity mode overlap. The strong thermal lensing, which is an unavoidable feature of multi-Watt end-pumping, is exploited in the present cavity design.

Thermal conductivity of a self-frequency-doubling laser crystal measured by use of optical methods

We present a new all-optical technique to measure the thermal conductivity of laser crystals. This technique can be used for crystals that are too small for direct measurement of thermal conductivity. We used this technique to measure the thermal conductivities of Nd:LYAB, with the result of 44 +/- 6% compared with that of Nd:YAG thermal conductivity.

Thermal lensing measurements in an intracavity LiIO 3 Raman laser

We present measurements of thermal lensing in a crystalline Raman laser, with negative focal lengths as short as 24cm measured for a Raman power ~1W.

A highly astigmatic diode end-pumped solid-state laser

A simple linear highly astigmatic laser cavity design has been analysed theoretically and demonstrated experimentally with Nd:YVO4. This cavity design is appropriate for high-power diode-laser-array end-pumping. The cavities presented are capable of generating Gaussian beams with general astigmatism, which have principal axes which rotate on propagation.

Influence of laser action on thermal loading in diode-pumped Nd:YVO4.

We present quantitative interferometric measurements of thermal lensing in diode-pumped Nd:YVO4 crystals with and without laser action. When laser action was inhibited the thermal loading was increased significantly. The fraction of absorbed power deposited as heat was found to be strongly dependent on upper laser-level loss mechanisms (ie. non-radiative decay, concentration-dependant quenching and Auger recombination).

1.1 W CW green self-frequency-doubled diode-pumped Yb:YAl(sub)3(BO(sub)3)(sub)4 laser

Infrared and self frequency doubled operation of the new laser material Yb:YAB has been reported. Laser operation in both cw and Q-switched regimes have been possible. In this report we investigate the road to higher power operation in this efficient laser material.