Near-field scanning technique for profiling single-mode fibres

1983 ◽  
Vol 19 (6) ◽  
pp. 190 ◽  
Author(s):  
D.H. Irving
Keyword(s):  
Near Field ◽  
Single Mode ◽  
Scanning Technique ◽  
Near Field Scanning

Near-Field Scanning Optical Microscopy Studies of Materials and Devices

MRS Bulletin ◽  
1997 ◽  
Vol 22 (8) ◽  
pp. 27-30 ◽  
Author(s):  
J.W.P. Hsu
Keyword(s):  
Optical Microscopy ◽  
Light Source ◽  
Optical Fibers ◽  
Force Feedback ◽  
Near Field ◽  
Single Mode ◽  
Field Zone ◽  
Research Activities ◽  
Scanning Optical Microscopy ◽  
Near Field Scanning

Near-field scanning optical microscopy (NSOM) provides a means to study optical and optoelectronic properties of materials at the nanometer scale. The key to achieving resolution higher than the diffraction limit is to place a subwavelength-sized light source—e.g., an aperture—within the near-field zone of the sample. In this case, the area of the sample illuminated is determined by the aperture size and not by the wavelength (see Figure 1). An image can then be formed by moving the sample and light source with respect to each other. While the principle of near-field optics is straightforward, its realization at visible-light wavelengths was not achieved until the invention of scanning-probe techniques in the 1980s. Since Betzig et al. demonstrated in 1991 that bright subwavelength apertures can be made by tapering and metal-coating single-mode optical fibers, research activities involving NSOM have increased tremendously. The later incorporation of shear-force feedback to regulate tip-sample separation adds another strength to NSOM. Using this distance regulation, a topographic image similar to that obtained by a conventional scanning force microscope is acquired simultaneously with the optical image. This provides a way to correlate structural and physical properties at the same sample positions and greatly simplifies interpretation of the NSOM data.

Characterization of Materials and Devices by Near-Field Scanning Optical Microscopy

1995 ◽  
Vol 406 ◽  
Author(s):  
B. B. Goldberg ◽  
H. F. Ghaemi ◽  
M. S. Ünlü ◽  
W. D. Herzog
Keyword(s):  
Low Temperature ◽  
Optical Microscopy ◽  
Near Field ◽  
Single Mode ◽  
Sample Surface ◽  
High Energy ◽  
Semiconductor Layer ◽  
Photocurrent Spectroscopy ◽  
Scanning Optical Microscopy ◽  
Near Field Scanning

AbstractNear field scanning optical microscopy (NSOM) is a recent technique where a tapered single-mode optical fiber probe is scanned over a sample surface at a height of a fraction of the wavelength. The tapered fiber provides a tiny aperture (a, ˜ 70nm) through which light is coupled and can yield resolutions as high as ˜, λ/40. We have used both room and low-temperature NSOM to study the local spectroscopic characteristics of a wide variety of material systems, from quantum dots and wires, to ordered GaInP, to heterojunctions and optoelectronic devices.Low temperature near-field photoluminescence spectroscopy was used to study spectral emission maps of a set of samples of GaInP epilayers with varying degrees of ordering. The samples exhibit two peaks, a low energy (LE) and a high energy (HE) peak. Our data are inconsistent with expectations that the LE peak is due to emission from domain boundaries and alternative models will be discussed. NSOM spectral maps can yield information about the spatial dependence of the local optical matrix elements. NSOM data on the emission mode structure of strained (In, Ga)As quantum well lasers has yielded new information on the source kinks in the light response at high currents, while local photocurrent spectroscopy using the tip as a point source of photons provides analysis of the semiconductor layer composition.

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