Optical wavelength-divison multi/demultiplexer

• US 5,107,359 A
• Filed: 11/22/1989
• Issued: 04/21/1992
• Est. Priority Date: 11/25/1988
• Status: Expired due to Fees

• Current Assignee: Ricoh Company Limited A Joint-Stock Company of Japan
• Original Assignee: Ricoh Company Limited
• Inventors: Ohuchida, Shigeru
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): NEGASH, KINFE MICHAEL
• Application Number:
  US07/440,275
• Time in Patent Office: 881 Days
• Field of Search: 370/3, 370/1, 350/96.16, 350/96.19, 359/124, 359/130
• US Class Current: 398/79
• CPC Class Codes: G02B 6/29311 Diffractive element operating in transmission
• CPC Class Codes: G02B 6/2938 for multiplexing or demultiplexing, i.e. combining or separating wavelengths, e.g. 1xN, NxM

Abstract

An optical wavelength-division multi/demultiplexer for use in an optical multiplex communication, comprises a transparent substrate having opposite sides. A transmission off-axis diffraction grating is formed on one side of the substrate, for passing light incident thereon while diffracting and converging the same. A light reflecting element such as a transmission off-axis diffraction grating or flat specular reflection surface is provided on the other side of the substrate, for reflecting the light diffracted by the transmission off-axis diffraction grating toward the transmission off-axis diffraction grating.

Claims

1. An optical wavelength-division multi/demultiplexer for use in an optical multiplex communication, comprising:

a transparent substrate having opposite sides;

a transmission off-axis diffraction grating, provided on one side of the opposite sides of said substrate, for passing light incident thereon at a Bragg angle while diffracting and converging said incident light; and

a light reflecting means, provided on an other side of the opposite sides of said substrate, for reflecting said light, diffracted and converge by said transmission off-axis diffraction grating, toward said transmission off-axis diffraction grating so that said incident light passes through said transmission off-axis diffraction grating twice.

2. A multi/demultiplexer according to claim 1, wherein said light reflecting means is a reflection type diffraction grating formed on said other side of said substrate.

3. A multi/demultiplexer according to claim 2, wherein said reflection type diffraction grating has a shape for correcting chromatic aberration created by said transmission off-axis diffraction grating.

4. A multi/demultiplexer according to claim 1, wherein said light reflecting means is a flat specular reflection surface formed on said other side of said substrate.

5. An optical wavelenght-division multi-demultiplexer for use with a first optical fiber for transmitting a multi-wavelength light including a plurality of light signals having different wavelengths, respectively, and with a plurality of second optical fibers for transmitting respective light signals having different wavelengths, respectively, comprising:

a transparent substrate having opposite sides;

a transmission off-axis diffraction grating, provided on one side of the opposite sides of said substrate, for passing light incident thereon at Bragg angle while diffracting and converging said incident light; and

a light reflecting means, provided on an other side of the opposite sides of said substrate, for reflecting said light, diffracted and converged by said transmission off-axis diffraction grating, toward said transmission off-axis diffratction grating so that said incident light passes through said transmission off-axis diffraction grating twice, p1 wherein said first and second optical fibers are disposed at said one side of said substrate.

6. A multi/demultiplexer according to claim 5, wherein said optical wavelength-division multi/demultiplexer is connected with said first and second optical fibers through a waveguide element comprising a base substrate and a waveguide layer formed thereon, said wavelength layer being formed with a slab guide adjacent to said transmission off-axis diffraction grating and with light wavelength passages each extending between said slab guide and one of said first and second optical fibers.