Optical waves without diffraction
Conventional optical devices have an inherent limitation: the level of feature detail is limited to half the wavelength of the radiation. Feature size and spacing between patterns are determined by the diffraction limit of light; therefore, shorter wavelengths are required to achieve better resolution. The incorporation of metals could contribute significantly to the development of near-field optical devices.The EU-funded project 'Active and passive exploitation of light at the nanometre scale' (APEX-SPP) is investigating the use of metals that will act as waveguides for electromagnetic energy below the diffraction limit of visible light. Specifically, APEX-SPP focuses on merging silicon photonics with plasmonics for designing silicon-based active or passive plasmonic devices. Silicon plasmonics offers optical mode sizes down to a fraction of the diffraction limit. These field enhancements can be used to boost optical linear and non-linear effects. To tailor linear and non-linear responses, the project focus is on identifying suitable plasmonic waveguide geometry.Project partners have produced new plasmonic lasers. Generating modes smaller than the diffraction limit, they managed to sustain excitation indefinitely by amplification. A study of dynamics on these short-time scales revealed that these short-pulse lasers can be used in ultrafast spectroscopy. APEX-SPP also plans to introduce surface plasmon nanolasers designed to operate with III-V semiconductor materials.A technology that squeezes electromagnetic waves into minuscule structures may yield a new generation of superfast computer chips and ultra-sensitive sensors for health care, defence and security.