Optomechanical nonlinearities

Optomechanical interactions in various types of photonic devices have been recently attracting a lot of interest [1]. The aim of this project is to investigate novel nonlinear optomechanical effects on a fibre platform, in which light causes nanostructures to move and then act back on the light so as to modulate it. To this end we have designed a new type of a microstructured fibre - a “dual-nanoweb“ fibre, consisting of two ultrathin and closely spaced glass membranes, attached to the inner wall of a fibre capillary (Fig. 1(a) - (c)). This fibre exhibits a giant optomechanical nonlinearity, exceeding the electronic Kerr nonlinearity by many orders of magnitude (Fig. 1(d)). We think it may trigger new developments in the fields of nonlinear optics, optical metrology and sensing [2,3]. As a PhD student you would get involved in dreaming up new nanostructures and fabricating them in our state-of-the-art fabrication cleanroom, as well as characterizing them optically and carrying out detailed theoretical studies.


  1. T. J. Kippenberg and K. J. Vahala, Cavity Optomechanics: Back-Action at the Mesoscale, Science 321, 5893, 1172 (2008).
  2. A. Butsch, C. Conti, F. Biancalana and P. St.J. Russell, Optomechanical Self-Channeling of Light in a Suspended Planar Dual-Nanoweb Waveguide, Phys. Rev. Lett. 108, 093903 (2012).
  3. A. Butsch, M. S. Kang, T. G. Euser, J. R. Koehler, S. Rammler, R. Keding and P. St.J. Russell, Optomechanical Nonlinearity in Dual-Nanoweb Structure Suspended Inside Capillary Fiber, Phys. Rev. Lett. 109, 183904 (2012).

Figure: (a) Scanning electron micrograph (SEM) of the dual-nanoweb fibre cross-section (diameter 100 ?m). (b) Near-field optical micrograph of the light emerging from the fibre end-face when white light is launched into the core. (c) The two nanowebs are ~440 nm thick and 22 μm wide, and the air gap is ~550 nm wide. (d) Frequency response of the optomechanical nonlinearity and its phase delay close to a 7 MHz resonance. The optomechanical nonlinearity is ~20,000 times larger than the Kerr nonlinearity at resonance.


Dr. Anna Butsch (