The Computational Nonlinear Optics group, headed by Dr Peter Horak, is interested in the theoretical and numerical investigation of a wide range of photonics systems.
On all projects we collaborate closely with other research groups, and the interaction between our modelling work and corresponding experiments is a main driving force in our research.
Our main partner groups within the ORC are:
P. Horak, W. Stewart, and W. H. Loh, Continuously tunable optical buffer with a dual silicon waveguide design, Opt. Express 19, 12456 (2011)
S. Dasgupta, F. Poletti, S. Liu, P. Petropoulos, D. Richardson, L. Grüner-Nielsen, and S. Herstrøm, Modeling Brillouin Gain Spectrum of Solid and Microstructured Optical Fibers Using a Finite Element Method, J. Lightwave Technol. 29, 22 (2011).
F. Poletti, Hollow core fiber with an octave spanning bandgap, Opt. Lett. 35, 2837 (2010)
A. Xuereb, T. Freegarde, P. Horak, and P. Domokos, Optomechanical cooling with generalized interferometers, Phys. Rev. Lett. 105, 013602 (2010)
R. T. Chapman, T. J. Butcher, P. Horak, F. Poletti, J. G. Frey, and W. S. Brocklesby, Modal effects on pump-pulse propagation in an Ar-filled capillary, Opt. Express 18, 13279 (2010)
F. Poletti and P. Horak, Dynamics of femtosecond supercontinuum generation in multimode fibers, Opt. Express 17, 6134-6147 (2009)
F. Poletti and P. Horak, Description of ultrashort pulse propagation in multimode optical fibers, J. Opt. Soc. Am. B 25, 1645 (2008)
F. Xu, P. Horak, and G. Brambilla, Optical microfiber coil resonator refractometric sensor, Opt. Express 15, 7888 (2007) and Opt. Express 15, 9385 (2007)
M. L. V. Tse, P. Horak, J. H. V. Price, F. Poletti, F. He, and D. J. Richardson, Pulse compression at 1.06um in dispersion-decreasing holey fibers, Opt. Lett. 31, 3504 (2006)
Current and recent research projects
Nonlinear Fibre Optics (Dr Horak, Dr Poletti)
The main focus of our current research is in the area of nonlinear optics in microstructured holey fibres. We investigate their unique capability to modify the nonlinear propagation of short laser pulses with the aim to understand and exploit pulse shaping techniques in space, time, and frequency. We use computer simulations as well as approximate analytical models to study a range of applications such as supercontinuum (white light) generation, soliton pulse compression, and red-green-blue (RGB) generation. In particular, we recently proposed a theoretical model to describe nonlinear mode-to-mode coupling which become significant for more complex and large-scale fibre structures and high laser powers. Applications of this work range from the scientific (medical and biological imaging, short-pulse spectroscopy), to the commercial (telecommunications, environmental sensing, laser welding), and to general purpose lightening.
High Harmonic Generation (Dr Horak)
Ultrafast laser pulses today can produce fields large enough to rip electrons out of the atoms of a neutral gas and then to accelerate these electrons so hard that they emit ultrashort wavelength radiation. Exploiting this effect, it will ultimately be able to build table-top coherent X-ray sources that are of fundamental interest for structural imaging on the nanoscale and even down to the molecular level. A particularly interesting geometry is to combine laser propagation, ionisation, and X-ray emission inside a single gas-filled capillary. We are currently investigating the delicate, highly nonlinear interaction between pump laser, gas, and X-rays to gain better understanding and, in due course, better control over such systems.
Design of Novel Hollow Core Microstructured Fibres (Dr Poletti)
Hollow core glass fibres, confining light by total external reflection, optical antiresonance or photonic bandgap effects, have recently opened up new routes for generating efficient nonlinear effects in gaseous or liquid media. The tremendous potential of these novel gas or liquid filled nonlinear waveguides for both pure science and device applications has generated significant interest in the fibre optics community. We investigate theoretically and numerically the physical waveguiding mechanisms of these fibres, to develop novel microstructured fibre designs with tailored spectral transmission bandwidths and group velocity dispersion for application in nonlinear processes at high field intensities in gases and liquids. We work in close collaboration with fibre fabricators and experimental groups at the ORC and across Europe.
Acousto-Optical Phenomena in Fibres (Dr Dasgupta)
Besides guiding light, optical fibres can also simultaneously guide acoustic waves, i.e., sound. In the nonlinear optical regime, the propagating light and sound waves interact with each other leading to many interesting acousto-optic phenomena. Amongst these, Brillouin scattering is perhaps the most important phenomenon that has vital implications for a wide range of applications in telecommunications, distributed sensing, fibre lasers, slow light generation etc. We have recently developed a finite-element based model for calculating the Brillouin gain characteristics of optical fibres with arbitrary refractive index profiles, and we are now studying and designing solid and microstructured optical fibres with tailored Brillouin gain characteristics suitable for various applications.
Quantum Optics and Optomechanics (Dr Horak)
In collaboration with the Quantum Control group at the School of Physics and Astronomy we are investigating the optical interaction of dilute, ultracold gases of atoms or molecules with microstructured surfaces. For example, we have recently identified novel optical cooling mechanisms which rely solely on the polarisability of the particles and do not require spontaneous emission. Generalisations of these schemes can even be exploited to optomechanically cool mesoscopic objects, such as micromirrors or micromechanical cantilevers. Such technologies will enable future generations of lab-on-the-chip, integrated atomic clocks, atom interferometers, quantum information processors, and portable ultra-precision sensors.
Please contact Dr Peter Horak if you would like any further information about the work of our Computational nonlinear optics group or would be interested to work with us.