Archive for October 2009

CoEP research featured again in AdelaideNow

October 22, 2009

Research being undertaken at Adelaide to provide in-situ sensing of chemicals using optical fibres has attracted a great deal of interest from the wine industry.

The technology, being developed at the University of Adelaide, will allow them to monitor and fix problems as they arise, without interfering with wine that should have been left in the barrel.

For more information, read the full article.

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The world is more nonlinear than we think

October 16, 2009

A team of scientists from the Institute for Photonics and Advance Sensing (IPAS) led by Dr. Shahraam Afshar have recently shown that optical fibres are more optically nonlinear than it was thought before. Through a fundamental study of optical nonlinear processes in optical fibres, Shahraam Afshar and his team have shown that the standard theories of nonlinear optical processes in waveguides have serious limitations when it comes to waveguides with sub-wavelength structures (nano-scale structures) made from high refractive index materials.

Theoretical simulation of a fibre mode

Theoretical simulation of a fibre mode

By developing a new and general theory of nonlinear optical processes, they have not only addressed these limitations but have also predicted new processes or effects that could have not been observed with the standard theories. The most important prediction of the new theory is that the light can be confined within an area twice smaller than fundamentally thought to be the minimum area. This results in higher light intensity, which in turn leads to higher nonlinearity of optical waveguides, which is described through a parameter called effective nonlinear coefficient.

gVsDiam

Variation in the nonliear coefficent as a function of core diameter as perdicted by the different models. SM: Standard Model, ASM: , VNSE: , VNSE ORTH:

Afshar’s new theory predicts that the effective nonlinear coefficient of optical waveguides, can be factor 2 or more higher than what is expected according to the standard theory. Such prediction greatly affects the design and performance of nonlinear photonic devices. Utilizing the fabrication facility of IPAS, a newly formed institute led by Pro. Tanya Monro, the team has recently been successful to fabricate the world’s smallest core fibre with record nonlinear coefficient. Using these fibres Afshar’s team has recently confirmed experimentally the prediction of their new theory. The results of these fundamental theoretical and experimental breakthroughs have been published in prestigious journals and attracted a lot of interest among the experts in the field.

Experimental confirmation of the change in nonlinearity as a function of core diameter, as predicted by the new model.

Experimental confirmation of the change in nonlinearity as a function of core diameter, as predicted by the new model.

The IPAS institute of the University of Adelaide has become a pioneer in establishing that:

The world is more nonlinear than we think

References

(1) S. Afshar V. and T. M. Monro, “ A full vectorial model for pulse propagation in emerging waveguides with subwavelength structurespart I:Kerr nonlinearity, ” Optics Express 17, 2298–2318 (2009).

(2) M. D. Turner, T. M. Monro and S. Afshar V., “ A full vectorial model for pulse propagation in emerging waveguides with subwavelength structures part II: Stimulated Raman Scattering, ” Optics Express 17, 11565–11581 (2009).

(3) S. Afshar V., W. Zhang and T. M. Monro, “ Experimental confirmation of a generalized definition of the effective nonlinear coefficient in emerging waveguides with subwavelength structures” CThBB6, CLEO Conference, Baltimore, USA (2009).

(4) T. M. Monro, W. Zhang, H. Ebendorff-Heiperiem, and S. Afshar V., “Emerging Nonlinear Optical Fibers: Revised Fundamentals, Fabrication and Access to Extreme Nonlinearity”, IEEE Journal of Quantum Electronics, Nov. Issue (2009)

(5) S. Afshar V., W. Zhang, H. Ebendorff-Heiperiem, and T. M. Monro, “Small core optical waveguides are more nonlinear than expected; Experimental confirmation”, Optics Letters, Accepted for publication.

Book Chapter:
(6) S. Afshar V., M. D. Turner and T. M. Monro, “Nonlinear optics in emerging waveguides: revised fundamentals and implications” in Supercontinuum Generation in Optical Fibers, edited by J. M.
Dudlley and J. R. Taylor, Cambridge University Press, under publication