Optical demultiplexers with grating reflectors

• US 5,825,520 A
• Filed: 08/11/1995
• Issued: 10/20/1998
• Est. Priority Date: 07/27/1992
• Status: Expired due to Term

• Current Assignee: Level 3 Communications LLC (Lumen Technologies, Inc.)
• Original Assignee: Ciena Corporation, General Instrument Corporation (CommScope Holding Company, Inc.)
• Inventors: Huber, David R.
• Primary Examiner(s): PASCAL, LESLIE C
• Application Number:
  US08/514,422
• Time in Patent Office: 1,166 Days
• Field of Search: 359/127, 359/130, 385/37, 385/24
• US Class Current: 398/87
• CPC Class Codes: G02B 6/2932 comprising a directional router, e.g. directional coupler, circulator
• CPC Class Codes: G02B 6/2938 for multiplexing or demultiplexing, i.e. combining or separating wavelengths, e.g. 1xN, NxM
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems
• CPC Class Codes: H04J 14/0206 Express channels arrangements
• CPC Class Codes: H04J 14/0209 Multi-stage arrangements, e.g. by cascading multiplexers or demultiplexers
• CPC Class Codes: H04J 14/0213 Groups of channels or wave bands arrangements

Abstract

The present invention provides an optical demultiplexer for demultiplexing an input signal containing a group of optical signals each at a different wavelength into at least two optical signals. The demultiplexer comprises a first optical transfer system comprising an optical circulator having at least three circulator ports for circulating optical signals from one port to the next port in a circulating direction. An input signal containing a group of optical signals is coupled to each at a different wavelength to a first of the circulator ports. A second circulator port optical path is coupled to the second circulator port, the second circulator port being the next circulator port in the circulating direction from the first circulator port. The second circulator port optical path includes a grating reflector for reflecting one of the group of optical signals back to the second circulator port. The reflected optical signal is circulated from the second circulator port to the third circulator port which is the next port in the circulating direction from the second circulator port while the unreflected optical signals from the group of optical signals passes through the grating reflector and continuing on the second circulator port optical path. A second optical transfer system comprising an optical circulator having at least three ports for the input and output of optical signals is optically coupled to the second circulator port optical path of the first optical transfer system at a position downstream of the grating reflector. An output line is coupled to the third circulator port of the first optical transfer system for receiving the reflected optical signal from the second circulator port, i.e., the demultiplexed optical signal.

Claims

1. An optical demultiplexer comprising:

an optical circulator having a plurality of ports, a first one of said plurality of ports being configured to be coupled to an optical communication path carrying a first plurality of optical channels, said first one of said plurality of ports receiving said plurality of optical channels, said plurality of optical channels being circulated from said first one of said plurality of ports to a second one of said plurality of ports;

a plurality of first in-fiber Bragg gratings connected in series and being coupled to said second one of said plurality of ports, said plurality of optical channels being output from said second one of said plurality of ports, each of said plurality of first in-fiber Bragg gratings respectively reflecting a selected first one of said plurality of optical channels back to said second port for output through a third one of said plurality of ports, at least a second one of said plurality of optical channels being different than said first ones of said plurality of optical channels being transmitted through said first plurality of in-fiber Bragg gratings; and

at least a second in-fiber Bragg grating coupled to said third one of said plurality of ports, said at least said second in-fiber Bragg grating reflecting a third one of said plurality of optical channels back to said third one of said plurality of ports for output through a fourth port, and transmitting at least a fourth one of said plurality of optical channels, a number of said in-fiber Bragg gratings respectively coupled to said second and third ones of said plurality of ports decreasing in a direction from said second one of said plurality of ports to said third one of said plurality of ports.