Post-processing offers new ways to control and manipulate the loss, dispersion, polarization state and nonlinear interaction of light in optical fibres. Over the past years, we have developed CO2 laser techniques to fabricate many different kinds of tapered and thermally processed structures, as well as novel side-scattering technique to characterize them [1]. Recently we have shown that, in a continuously twisted “endlessly single-mode” photonic crystal fibre (PCF), leaky ring-shaped orbital angular momentum states are excited in the cladding, causing dips at certain wavelengths in the transmission spectrum [2]. In addition to their fundamental scientific interest as guided wave devices in “twisted space,” helical PCF has many potential applications in wavelength filtering and dispersion control. As a PhD student you would become expert at all these techniques, as well as developing methods for producing low loss splices between fibres with different cross-sectional structures, and for rapid optical characterisation of the processed structures.


  1. L. Y. Zang, T. G. Euser, M. S. Kang, M. Scharrer and P. St.J. Russell, Structural analysis of photonic crystal fibers by side scattering of laser light, Opt. Lett. 36, 1668-1670 (2011).
  2. G. K. L. Wong, M. S. Kang, H. W. Lee, F. Biancalana, C. Conti, T. Weiss and P. St.J. Russell, Excitation of orbital angular momentum resonances in helically twisted photonic crystal fiber, Science 337, 446–449 (2012).

Figure: Perspective view of a helically twisted PCF.


Dr. Gordon Wong (