Novel Light Sources
Developing, fibre, solid-state, planar waveguide, supercontinuum lasers and fibre-based nonlinear devices such as frequency inverts and optical switches. Using state of the art laser technology to perform measurements of extreme accuracy and precision.
- Novel Light Sources Overview
IPAS novel light sources research combines fundamental and applied physics to generate and deliver tailored light for medicine, national security, environmental monitoring and fundamental physics applications. Our world leading research includes:
- Fibre and planar waveguide lasers
- High stability lasers
- Fibre-based nonlinear devices and super-continuum sources
- Solid-state lasers
- Frequency standards
- Frequency combs and spectroscopy
- Quantum atom-fibre photonics.
Real world applications for these sources include:
- High-speed and high-resolution molecular spectroscopy for trace-gas detection and biological sensing
- Frequency reference for optical and radio astronomy
- Magnetic sensor for detecting heart beats
- World leading temperature measurements
- Atmospheric and coherent laser radars
- Laser-based electronic warfare systems.
- Precision Measurement
A defining feature of our technological society is a hunger for more accurate and precise measurement and sensing. Important real world applications such as: the Global Positioning System (GPS), magnetic imaging, radar, optical fibre communications and even mobile phones, all rely on developing ever more accurate and precise measurements.
The Precision Measurement Group works to build instruments to meet this technological demand. We develop and extend measurement platforms of high value to fundamental physics; with an increasing focus on industrial, medical and defence contexts.
- Laser and Optical Systems Research for Precision Sensing
The light sources are a key component in an active sensing system. Depending on the application a new light source can open new paradigms in laser based active remote sensing. This can be because the source has new spectral properties, increased robustness or considerably reduced costs.
To fully capitalize on new light sources, we also research how to integrate these sources into laser based active remote sensing platforms. We have extensive experience in lidar development and deployment, an example of which is shown below. These images are from an upper atmosphere temperature profiler that is used to study the temperature of the atmosphere up to 90 km above the Earth’s surface. This is highest energy collecting area product lidar in the Southern Hemisphere. Currently, we are focusing our efforts on developing lidar using Er:YAG and Erbium ZBLAN lasers.
Mid Infrared Fibre Lasers
In recent years there has been considerable interest in the shorter end of the mid-infared spectrum ie wavelengths between 2.5 µm and 6 µm because many compounds exhibit strong absorption features that can be used to identify species. Of particular interest is the functional group absorption region between 2.5 µm and 4 µm which offers opportunities for sensing and the precise and highly reproducible modification of industrial and biomedical materials [5, 6]. This region can also provide absorption features relevant to combination and overtone absorptions from the fingerprint region and benefits from the wide availability of fast and more sensitive photodiode detection.
Convenient sources in the wavelength band between 3 -5µm have until very recently proven quite difficult to obtain. Quantum Cascade Lasers (QCLs) have proven to be extremely successful at generating significant power in convenient packages at longer wavelengths but this performance has proven difficult to translate to shorter wavelengths. Fibre lasers have produced very high power levels (~10 kW) at shorter wavelengths but to date this has not been replicated at longer wavelengths. In fact, prior to 2014 the highest power level reported from a mid-infrared fibre laser was 10 mW.
In early 2014 we reported that the efficiency of mid-infrared transitions can be dramatically enhanced by utilizing so called dual-wavelength pumping. Using this technique, we initially demonstrated that 0.25 watts of laser emission and then followed this up with a 1.5 W demonstration in early 2016. We have also demonstrate a light source that is tuneable from 3.35 µm and 3.8 µm.
These important demonstrations are just the beginning we believe that we can demonstrate convenient pulsed mid-infrared lasers with rep-rates above 30 kHz with peak powers approaching 1 kW. The transition on which these lasers are based have extremely broad emission bandwidth so once mode-locked operation has been achieved it is not inconceivable to generate pulses with sub 100 fs performance. Further, some initial power scaling estimates suggest that at least 10 Watts of power should be achievable. Dual-wavelength pumping opens the intriguing possibility of enabling convenient sources that emit between 4-5µm using other transitions.
Erbium based crystal lasers is the only direct laser source that operates in the peak of the eye-safe band and can generate significant peak power. Our recent results have shown that 10 mJ pulses with 4nS duration are possible. The resulting peak power is the highest ever demonstrated from an Er:YAG platform. This development opens a pathway for new simple eye-safe range finders.
A fortunate coincident of nature means this erbium transition aligns with one of the strongest overtones of methane absorption. Methane is the major constituent in natural gas which if completely combusted has the lowest greenhouse footprint of any of the fossil fuels. Leaks from natural gas infrastructure undermine this advantage and potentially create a significant hazard. Based on our existing laser systems we are designing a new laser architecture that will be incorporated into a world leading methane lidar system.
- Fibre and Planar Waveguide Lasers
Our Fibre and Planar Waveguide Lasers research is focussed on developing and optimising new concepts in fibre and planar waveguide lasers. Our research is driven by the challenge to develop lasers that operate in fringe regimes and possess extreme capabilities from compact architectures. This work drives the development of unique rare-earth doped glasses and fibres at IPAS.
- Nonlinear Optics
Our expertise in modelling nonlinear processes in nanoscale waveguides could provide future solutions for high-speed optical switches, laser sources and sensing architectures. The ongoing development of fundamental theory has led to new models that predict a novel ‘self-flipping of polarization states’ that are being explored via two new collaborations. We hold high hopes for some very interesting new light sources in the near future.
- Solid State Lasers
Solid State Laser research at IPAS focuses on the development of low
noise and high-power systems for specific applications including ultra high precision measurement, spectroscopy, and remote sensing. This year we have demonstrated a laser that produced the shortest pulses ever achieved by an Er:YAG laser pumped by inexpensive laser diodes. This is approaching the pulse durations needed for this laser to replace more complicated non- linear optics based solutions for long distance laser range finders.