Breaking the Diffraction Barrier: Optical Microscopy on a Nanometric Scale

Abstract

In near-field scanning optical microscopy, a light source or detector with dimensions less than the wavelength (lambda) is placed in close proximity (lambda/50) to a sample to generate images with resolution better than the diffraction limit. A near-field probe has been developed that yields a resolution of approximately 12 nm ( approximately lambda/43) and signals approximately 10(4)- to 10(6)-fold larger than those reported previously. In addition, image contrast is demonstrated to be highly polarization dependent. With these probes, near-field microscopy appears poised to fulfill its promise by combining the power of optical characterization methods with nanometric spatial resolution.

Enhanced transmission versus localization of a light pulse by a subwavelength metal slit

“…The most impressive features of the optical elements are resonant enhancement and spatial localization of optical fields by the excitation of electron waves in the metal (for an example see, e.g. [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25]). Recently, some nanostructures namely a single subwavelength slit, a grating with subwavevelength slits and a subwavelength slit surrounded by parallel deep and narrow grooves attracted a particular attention of researchers.…”

“…Recently, some nanostructures namely a single subwavelength slit, a grating with subwavevelength slits and a subwavelength slit surrounded by parallel deep and narrow grooves attracted a particular attention of researchers. The study of resonant enhanced transmission and collimation of waves in close proximity to a single subwavelength slit acting as a microscope probe [1,2,3] was connected with developing near-field scanning microwave and optical microscopes with subwavelength resolution [4,5,6,7]. The resonant transmission of light by a grating with subwavevelength slits and a subwavelength slit surrounded by grooves is an important effect for nanophotonics [8,9,10,11].…”

Near-Field Spectroscopic Studies of Fluorescence Quenching by Charge Carriers

“…(7,5,9) This approach provides a highly sensitive mechanism for tip-sample control, and eliminates the need for the more cumbersome shear-force feedback mechanism in which an additional laser and photodiode are required. (5,10,11) …”

Focusing and Scanning Microscopy with Propagating Surface Plasmons

“…As the basic constituents of cells and nanotechnological devices are smaller than the wavelength of visible light, a variety of methods [1,2], including scanning near-field nanoprobes [3][4][5], have been developed for imaging below the diffraction limit. Current far-field methods exploit either the high refractive index of immersion media [6] or the photophysics of molecules [7][8][9][10]] to obtain high resolution images. Plasmonic structures are envisioned to enable surface-bound imaging with a resolution much below the optical wavelength, and indeed stationary hot spots [11][12][13] of subwavelength size can be generated from plasmons propagating in such structures.…”