AVS 45th International Symposium
    Nanometer-scale Science and Technology Division Thursday Sessions
       Session NS-ThP

Paper NS-ThP14
Electromagnetic Coupling Efficiency of a Metal Coated Optical Fiber Tip

Thursday, November 5, 1998, 5:30 pm, Room Hall A

Session: Nanometer-Scale Science and Technology Division Poster Session
Presenter: L. Alvarez, CICESE, Mexico
Authors: L. Alvarez, CICESE, Mexico
M. Xiao, UNAM, Mexico
Correspondent: Click to Email
The optical coupling of a metal coated optical fiber tip is calculated by using the direct moment method. The purpose of the calculation is to study the transmission efficiency of the near field probe tips widely used in the scanning near field optical microscopy. In the scanning near field optical microscopy, the near field probe is often made of tapped optical fiber tip which is coated with a metallic thin layer to form a subwavelength aperture at the very end of the tip. It is of great importance to study the transmission efficiency of the tip as functions of the size of the aperture, the thickness of the metal coat as well as the shape and optical characters of the fiber tip. One wants to know that for a given incident light, how much light would effectively contribute to the final readout of the microscope. In the literature in near field optics, the tip transmission was studied with various two dimensional simulations and with microscopic discretional theories. In the present work, a general three dimensional electromagnetic theory is however proposed. As examples, numerical results of the coupled electromagnetic waves as functions of the aperture size, the coat thickness and the materials properties of the fiber tip are presented for the simplified case where the incident light is assumed to be a plane wave, and the results are discussed with regards to the imaging of the scanning near field optical microscope. Finally, it is pointed out that the proposed model calculation would be useful to provide guidances for the manufacture of the probe tip in the scanning near field optical microscopy.