The University of Southampton

Scanning Near-Field Optical Microscopy

Scanning near-field optical microscopy (SNOM) is an imaging technique that can work beyond the diffraction limit. It can do this by collecting the non-propagating evanescent field, which exists up to a few nanometres away from a sample’s surface. This is achieved by positioning a very small aperture (usually a glass fibre heated and pulled down to form a sharp tip) just a few nanometres from a sample’s surface. 

Surpassing the resolution of standard optical microscopes, SNOM can investigate the local electric field properties of devices that have features much smaller than the wavelength of light under study. The resolution of SNOM is limited by the aperture size of the collector, rather than the wavelength of light used to image.

Our group uses SNOM’s unique ability of collecting the evanescent wave to investigate the properties of waveguides. We have studied the electric field behaviour inside fibre Bragg gratings, the mode profiles in micro-structured fibres, supercontinuum generation in highly nonlinear waveguides, and the inter-modal delay of pulses inside waveguides. Within the group, we have the unusual ability to combine ultra-fast science with the high-spatial resolution of SNOM. This ability enables us to investigate phenomena with femtosecond time resolutions and nanometre spatial resolutions.

Recently completed projects

Recent work has demonstrated the ability to track and measure the inter-modal delays of pulses propagating inside a waveguide. Using the Optoelectronics Research Centre’s (ORC)’s FAST lab, the group experimentally observed the delays between pulses belonging to separate waveguide modes, as a function of position down the waveguide. 

The group also developed a numerical model to investigate the properties that influence the evolution of a supercontinuum in a highly-nonlinear waveguide. This has been compared with data taken from the SNOM setup where the evolution of supercontinua was directly observed using a spectrally resolving configuration.


To search for more publications visit our publications database

3767 — T.Chaipiboonwong, P.Horak, J.D.Mills, W.S.Brocklesby, Numerical study of nonlinear interactions in a multimode waveguide, Optics Express 2007

3741 — T.Chaipiboonwong, P.Horak, J.D.Mills, W.S.Brocklesby, Numerical simulation of continuum generation in a multimode nonlinear waveguide, CLEO/Europe-IQEC 2007 Munich 17-22 Jun 2007 CD10-2-FRI (accepted)

3451 — J.D.Mills, T.Chaipiboonwong, W.S.Brocklesby, J.J.Baumberg, M.D.B.Charlton, M.E.Zoorob, M.C.Netti, Spectral evolution of femtosecond pulses in nonlinear waveguides: measing continuum generation and group velocity with NSOM, NFO-9 Lausanne 10-15 Sep 2006 312 

3395 — J.D.Mills, T.Chaipiboonwong, M.D.B.Charlton, M.E.Zoorob, C.Netti, J.J.Baumberg, W.S.Brocklesby, Observation of the developing optical continuum along a nonlinear waveguide, Optics Letters 2006 Vol.31(16) pp.2459-2461

3394 — J.D.Mills, T.Chaipiboonwong, M.D.B.Charlton, C.Netti, M.E.Zoorob, J.J.Baumberg, W.S.Brocklesby, Group velocity measurement using spectral interference in near-field scanning optical microscopy, Applied Physics Letters 2006 Vol.89 pp.051101/1 - 051101-3

3356 — J.D.Mills, T.Chaipiboonwong, M.D.B.Charlton, M.E.Zoorob, M.C.Netti, J.J.Baumberg, W.S.Brocklesby, Waveguide group velocity determination by spectral interference measurements in near-field optical scanning microscopy, CLEO/QELS 2006 Long Beach, California 21-25 May 2006 QTuA1 

3355 — T.Chaipiboonwong, J.D.Mills, M.D.B.Charlton, M.E.Zoorob, M.C.Netti, J.J.Baumberg, W.S.Brocklesby, Visualization of optical continuum evolution along a nonlinear waveguide, CLEO/QELS 2006 Long Beach, California 21-25 May 2006 QFE5 

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