Raman spectroscopy using a fiber optic probe with subwavelength aperture

Abstract

Raman spectroscopy with subwavelength spatial resolution of a diamond sample was recorded using a tapered fiber optical probe in conjunction with a conventional Raman spectrometer. The experiment demonstrates the potential of suboptical wavelength resolution analytical spectroscopy. The tapered fiber optical probe with an aperture of around 100 nm, served as the means for delivering pump radiation while simultaneously collecting the Stokes radiation from the diamond specimen. Comparing the magnitude of the Raman scattering measured with the submicron single mode fiber probe to similar signals obtained with a nontapered probe made of the same type of fiber, illustrates the potential increase in effective optical aperture resulting from the close approach of the fiber to the surface.

Characterization of light collection through a subwavelength aperture from a point source

“…1(b)). While our focus is to apply our findings to design better type-II ABIDs, this geometry may also be of relevance to research areas, such as near field Raman scattering [18] and near field radiation force [19]. In Section 2, we will report on our experimental measurements of the collection mode point spread functions (CPSFs) (formally defined in Section 2) for different aperture sizes.…”

Tip-Enhanced Raman Spectroscopy

“…However, for practical reasons, it would be more difficult to detect the weak signals in the nanoscale since smaller apertures make the near-field signal smaller. This is crucial particularly for Raman applications since Raman scattering cross section is extremely small, which results in the use of large aperture (poor resolution) or unrealistic long acquisition time [9,10]. On the other hand, additional signal enhancement can be expected in the case of apertureless-type probes especially when the probes are made of a metal.…”

Imaging and spectroscopy through plasmonic nano-probe

“…Near-field experiments have mostly been developed and operated in the visible wavelength region [9][10][11][12][13][14][15][16][17][18][19][20]. In this wavelength range, ANSOM techniques combined with Raman and fluorescence spectroscopy are commonly used.…”

“…With the aid of the STM invention, scanning probe microscope technique matured, and in 1984, Pohl et al reported the fundamental technique of NSOM [4], where they used an aperture type probe coated with thin metal films. Following this, NSOM has been exploited for many applications, such as spectroscopy and optical memory, by using an aperture type probe [9,10]. The early stage of NSOM has accessed the chemical properties of samples mainly by a e-mail: yuika@ap.eng.osaka-u.ac.jp fluorescence spectroscopy.…”