SINGLE-MODE DIELECTRIC WAVEGUIDE

• US 3,659,916 A
• Filed: 07/28/1970
• Issued: 05/02/1972
• Est. Priority Date: 07/28/1970
• Status: Expired due to Term

• Current Assignee: Enrique Alfredo Jose Marcatili
• Original Assignee: Enrique Alfredo Jose Marcatili
• Inventors: Marcatili, Enrique Alfredo Jose
• Primary Examiner(s): Corbin, John K.
• Application Number:
  US05/059,014
• Time in Patent Office: 644 Days
• Field of Search: 350/96WG
• US Class Current: 385/132
• CPC Class Codes: G02B 6/122 Basic optical elements, e.g. light-guiding paths
• CPC Class Codes: H01P 1/161 sustaining two independent orthogonal modes, e.g. orthomode transducer combining or separating polarisations and frequencies H01P1/2131

Abstract

This application describes a single-mode dielectric waveguide for guiding electromagnetic wave energy. The guide comprises a low-loss dielectric substrate in which a thin, low-loss, dielectric strip of higher refractive index is embedded. In general, such a guide is capable of supporting a plurality of modes of two orthogonally-polarized families of modes. To limit the waveguide to single-mode operation, the cross-sectional dimensions are limited so that the guide is incapable of supporting modes higher than the fundamental mode of each of the two families of modes. One of two fundamental modes is then supported by either placing a lossy material along one surface of the guiding strip, thereby making the guide much lossier to one of the two fundamental modes or, alternatively, by placing a higher refractive index material along the strip, thereby destroying the guiding capability of the waveguide with respect to one of the two fundamental modes.

Claims

1. A waveguide for guiding electromagnetic wave energy comprising:

an elongated, low-loss dielectric guiding strip, having a refractive index n and an essentially rectangular cross section, embedded in a low-loss dielectric substrate of lower refractive index;

said substrate contacting the two narrow surfaces and one of the wide surfaces of said strip; and

a high admittance material having a refractive index whose magnitude is larger than the refractive index of said strip contacting the other wide surface of said strip;

characterized in that;

the narrow dimension t and the wide dimension w of said strip are given by and where the refractive index of the portion of substrate in contact with said narrow surfaces is n(1 - Delta '"'"''"'"'), the refractive index Of the portion of substrate in contact with said one wide surface is n(1 - Delta ), and lambda is the free space wavelength of said wave energy.

2. The waveguide according to claim 1 wherein Delta '"'"''"'"' is smaller than Delta .

3. The waveguide according to claim 1 wherein Delta '"'"''"'"' Delta .

4. The waveguide according to claim 1 wherein said material is a metal.

5. The waveguide according to claim 1 wherein said material is a semiconductor