Raman Laser Technology Research Program
Overview
Diode-pumped Raman lasers are practical and efficient sources of laser output at otherwise "hard to reach" wavelengths. Based on conventional Nd laser technology, they use stimulated Raman scattering (SRS) in nonlinear crystals to shift the output wavelength further into the infrared, with conversion efficiencies typically as high as 70%. When combined with frequency doubling, efficient conversion to the yellow orange spectral regions, and the UV region can occur.
In recent years, we have enjoyed great success in targeting the yellow-orange spectral region for medical and defence applications, developed techniques for obtaining wavelength-selectable output across the green-yellow-red spectral region, and most recently demonstrated cw Raman laser-based devices operating in the infrared and yellow spectral regions.
The main focus of our research program over the next 2years are the development of continuous-wave Raman lasers, the development of UV Raman-based laser sources, pulse energy scaling of Raman lasers, and employing novel resonator configurations for Raman lasers.
Key Research Areas
Raman lasers are unique in a number of ways and the physics involved gives rise to interesting and unusual effects. It is an understanding of this physics which has enabled us to develop such innovative laser devices and novel ways of operating them. We have research projects aimed at understanding the optical field dynamics of Raman lasers, through a combination of experimental studies and quite recently through numerical modelling studies (with David Spence).
Continuous-wave Raman lasers
We have recently made advances which enable us to obtain cw operation of yellow lasers. The best results to date are 320mW fully cw output at 588nm, and 700mW output at 588nm (50% duty cycle). These lasers are practical, efficient diode-pumped devices, with diode to yellow efficiency up to 3.2%. Ongoing research is aimed at improving improve the conversion efficiency, power scaling, device miniaturisation and demonstrating wavelength-selectable output between green, yellow and red wavelengths.
UV Raman-based laser sources
This program concerns the development of crystalline Raman laser-based sources which operate in the UV spectral region. Based on well-established, robust Nd laser technology, these sources will operate at discrete wavelengths in the UV spectral regions. It is anticipated that around 30 different wavelengths in the range 266nm to 400nm can be generated by appropriate choice of laser and Raman media and resonator design. We will also explore means by which output can be easily switched between two or more of these wavelengths
In preliminary experiments we have achieved 250mW at 289nm. Lower powers up to 50mW at 8 wavelengths between 266nm and 308nm by frequency conversion of a Q-switched green laser producing 1.2W at 532nm
Pulse energy scaling of Raman lasers
This proposed project aims to demonstrate pulse energy scaling of all-solid-state intracavity crystalline Raman lasers to joule levels in the infrared and, by way of intracavity frequency-doubling, to sub-joule (hundreds of millijoules) levels in the visible. Operation in both high-energy quasi-CW (100s ms) single pulses and pulse trains, and high-energy nanosecond (1-10ns) pulses at low pulse rates will be encompassed. Nonlinear frequency-doubling of high-energy visible outputs will be used to generate ultraviolet wavelengths with pulse energies up to 10mJ .
Key aspects of this project include materials optimisation for high pulse energy Raman lasers, critical assessment of physical processes affecting pulse-energy scaling, and novel resonator designs for efficient high pulse-energy Raman lasers
Numerical modelling of Raman lasers
Raman lasers are unique in a number of ways and the physics involved gives rise to interesting and unusual effects. It is an understanding of this physics which has enabled us to develop innovative laser devices and novel ways of operating them.
Recent numerical modelling studies of cw Raman lasers have been highly beneficial at elucidating the optical field dynamics of Raman lasers, with verification by experimental studies. We propose to expand these modelling studies further to address various issues relating to the performance and features of a range of cw and pulsed Raman lasers.
Emphasis on Collaboration
Many of our research programs have involved a strong collaboration aspect with industry partners who have an interest in co-developing laser sources with output characteristics to match the requirements for their applications. Devices have been developed in partnership with DSTO (Defence Science and Technology Organisation), a European medical laser manufacturer (un-named), and we have also seen the formation of a spin-off company, Lighthouse Technologies to commercialise some of our Raman laser technology.
We will continue to establish collaborative links with research organisations and companies who have an interest in developing laser sources, laser applications or laser-based instrumentations, and invite expressions of interest from such organisations.
Projects for Students
A range of projects within the key research areas described above are available for interested students, including honours, masters and PhD and also exchange scholars. These can be tailored to suit applicants strengths or particular interests (eg. theoretical, experimental, industry-related).
Acknowledgements
Our Raman laser research has been supported under the Australian Research Council's Discovery Project Scheme since 2001.
Contacts
| Phone | Name | Room | Position | |
| 8927 | Dekker, Peter | dekker @ ics.mq.edu.au | E7B 235 | Research Fellow |
| 8965 | Mildren, Richard | rmildren @ ics.mq.edu.au | E7A 207 | Research Fellow |
| 8929 | Lee, Andrew | alee @ ics.mq.edu.au | E7B 225 | Research Fellow |
| 8932 | Pask, Helen | hpask @ ics.mq.edu.au | E7A 316 | Research Fellow |
| 8645 | Piper, Jim | jim.piper @ vc.mq.edu.au | E11A 153 | Deputy Vice-Chancellor (Research) Professor of Physics |
| 8973 | Spence, David | dspence @ ics.mq.edu.au | E7A 322 | Research Fellow |