D. Mudge

Thermally induced birefringence in Nd:YAG slab lasers

We study thermally induced birefringence in crystalline Nd:YAG zigzag slab lasers and the associated depolarization losses. The optimum crystallographic orientation of the zigzag slab within the Nd:YAG boule and photoelastic effects in crystalline Nd:YAG slabs are briefly discussed. The depolarization is evaluated using the temperature and stress distributions, calculated using a finite element model, for realistically pumped and cooled slabs of finite dimensions. Jones matrices are then used to calculate the depolarization of the zigzag laser mode. We compare the predictions with measurements of depolarization, and suggest useful criteria for the design of the gain media for such lasers.

Power scalable TEM/sub 00/ CW Nd:YAG laser with thermal lens compensation

We present finite-element analysis and experimental results to validate our approach for building high-power single-mode Nd:YAG lasers. We show that the thermooptical and thermomechanical properties of a slab laser can be controlled. This is essential for the use of the proposed unstable resonator, We include demonstration of an efficient subscale laser operating at 20 W TEM/sub 00/.

Compensation of Strong Thermal Lensing in High-Optical-Power Cavities

In an experiment to simulate the conditions in high optical power advanced gravitational wave detectors, we show for the first time that the time evolution of strong thermal lenses follows the predicted infinite sum of exponentials (approximated by a double exponential), and that such lenses can be compensated using an intracavity compensation plate heated on its cylindrical surface. We show that high finesse approximately 1400 can be achieved in cavities with internal compensation plates, and that mode matching can be maintained. The experiment achieves a wave front distortion similar to that expected for the input test mass substrate in the Advanced Laser Interferometer Gravitational Wave Observatory, and shows that thermal compensation schemes are viable. It is also shown that the measurements allow a direct measurement of substrate optical absorption in the test mass and the compensation plate.

Observation of three-mode parametric interactions in long optical cavities

C. Zhao, L. Ju, Y. Fan, S. Gras, B. J. J. Slagmolen, H. Miao, P. Barriga, and D. G. Blair, D. J. Hosken, A. F. Brooks, P. J. Veitch, D. Mudge, and J. Munch

High-power diode-laser-pumped CW solid-state lasers using stable-unstable resonators

We present a novel design for an efficient, high power (>100 W), continuous-wave (CW) Nd:YAG laser with diffraction-limited performance. It uses side-pumped, sidecooled, zigzag slab which is incorporated in a stable-unstable resonator that has a variable reflectivity output coupler. A geometric magnification of at least 1.3 in the unstable direction can be achieved. Modeled performance characteristics are presented.

A compact injection-locked Nd:YAG laser for gravitational wave detection

We have designed and characterized a diode-pumped injection-locked Nd:YAG laser suitable for precision metrology. The laser uses a simple side-pumped laser architecture and is compact, efficient, stable, and scalable. The frequency stability of the injection-locked slave laser is shown to be limited by the monolithic master oscillator and its intensity noise is 4/spl times/10/sup -6/ Hz/sup -1/2/ at 1 kHz.

ACIGA's high optical power test facility

Advanced laser interferometer detectors utilizing more than 100 W of laser power and with ~106 W circulating laser power present many technological problems. The Australian Consortium for Interferometric Gravitational Astronomy (ACIGA) is developing a high power research facility in Gingin, north of Perth, Western Australia, which will test techniques for the next generation interferometers. In particular it will test thermal lensing compensation and control strategies for optical cavities in which optical spring effects and parametric instabilities may present major difficulties.

High-power Nd:YAG lasers using stable–unstable resonators

The development of a power-scalable diode-laser-pumped continuous-wave Nd:YAG laser for advanced long-baseline interferometric detectors of gravitational waves is described. The laser employs a chain of injection-locked slave lasers to yield an efficient, frequency-stable, diffraction-limited laser beam.

Gingin High Optical Power Test Facility

The Australian Consortium for Gravitational Wave Astronomy (ACIGA) in collaboration with LIGO is developing a high optical power research facility at the AIGO site, Gingin, Western Australia. Research at the facility will provide solutions to the problems that advanced gravitational wave detectors will encounter with extremely high optical power. The problems include thermal lensing and parametric instabilities. This article will present the status of the facility and the plan for the future experiments.

Status of the Australian Consortium for Interferometric Gravitational Astronomy

We report the status of research and development being undertaken by the members of the Australian Consortium for Interferometric Gravitational Astronomy.