New Age Fiber Crystals

Dr. Philip Russell, Max-Planck Research Group, Institute for Optics, Information & Photonics, University of Erlangen-Nüremberg, Germany

Abstract

Photonic crystal fibres (PCFs) have been the focus of increasing scientific and technological interest since the first working example was reported in 1996 (for reviews see [1-4]). Although superficially similar to a conventional hair-thin glass optical fibre, PCF has a unique microstructure, consisting of an array of microscopic hollow channels running along its entire length. These channels act as optical barriers or scatterers, and suitably arranged can "corral" light within a central core (either hollow or made of solid glass). PCF can trap light in two different ways: by a modified form of total internal reflection, when the core must have a higher average refractive index than the photonic crystal cladding; and by a two-dimensional photonic bandgap, when the index of the core is uncritical - it can be hollow or filled with material. Light can be controlled and transformed in these fibres with unprecedented freedom, allowing for example precision guidance of light in a narrow hollow core, the creation of highly nonlinear PCFs with accurately controlled dispersion profiles, the design of fibres that guide only one mode at all wavelengths, and the observation of stimulated Raman scattering in hydrogen at threshold powers six orders of magnitude lower than ever seen before in single-pass geometries. Recently in Erlangen we have been using PCF as a means of realizing ultra-long silica-air nanostructures, both empty and selectively filled with metal or semiconductor. The photonic and phononic characteristics of these structures turn out to be very intriguing. For example, the microwave sound can be trapped in a nanostructured glass core, permitting the creation of artificial "Raman-active molecules" that can be used to produce low-threshold spectral broadening of laser light [5], and light can be coupled into guided surface plasmon waves on metallic nanowires [6]. These are just a few examples of how the PCF concept has ushered in a new and more versatile era of fibre optics, with a multitude of different applications spanning many areas of science.

Extruded SF6 glass ("holey") fiber for producing a super-continuum out to 2300nm.
[1] P. St.J. Russell, Science 299, 358 (2003).
[2] P. St.J. Russell, Journal of Lightwave Technology 24, 4729 (2006).
[3] P. St.J. Russell, Optics and Photonics News 18, 26 (2007).
[4] P. St.J. Russell, IEEE Lasers & Electro-Optics Society Newsletter 21, 11 (2007).
[5] M. S. Kang et al., submitted to Nature Physics (2008).
[6] H. W. Lee et al., Applied Physics Letters 93, 111102 (2008).

Biography

Philip Russell is Director of the Max-Planck Research Group for Optics, Information & Photonics at the University of Erlangen, Germany. In January 2009 he will become a founding Director of the new Erlangen-based Max-Planck Institute for the Science of Light. From 1996 to 2005 he founded and led the Photonics & Photonic Materials Group at the University of Bath. He specializes in periodic structures, nonlinear optics, waveguides and their applications. A Fellow and Director-At-Large of the Optical Society of America, in 2000 he won its Joseph Fraunhofer Award/Robert M. Burley Prize for the invention of photonic crystal fibre. In 2005 he was elected Fellow of the Royal Society and received the Thomas Young Prize of the UK Institute of Physics and the Körber Prize for European Science.