ORC Seminar Series

“Optical superresolution without evanescent fields”

Date: Wednesday 8 August 2007
Venue: Lecture Theatre B, Building 46, University of Southampton
Time: 2pm

The resolution of a conventional optical microscope is generally believed to be limited to about half the wavelength of light, due to the loss of evanescent fields in the far-field. Many existing approaches for achieving optical superresolution are based on the idea to recover evanescent fields, such as superlens. Here we demonstrate that evanescent fields are actually not necessary elements to form subwavelength fields. Subwavelength field structures can be constructed only by propagating fields, therefore superresolution in the far-field is achievable using conventional optical microscope. Using an array of nanoholes drilled on a metal screen, we observed subwavelength spots in the far-field both by a scanning aperture optical microscope and a conventional optical microscope. These observations are confirmed by theoretical simulations without involving evanescent fields. The results are linked to a phenomenon called superoscillation. It provides a complete new way to achieve superresolutions and may open a flood gate for many novel applications in optics.

Dr Fu Min Huang is a Research Fellow at the EPSRC Nanophotonics Portfolio Centre, Optoelectronics Research Centre, University of Southampton. He was awarded a MSc by Peking University, China in 1997. He received a PhD degree from the University of London, Kings College in 2005. His expertise is in Scanning Near-Field Optical Microscopy and Raman Spectroscopy.