Optical energy selector apparatus and method

• US 6,014,480 A
• Filed: 11/21/1997
• Issued: 01/11/2000
• Est. Priority Date: 11/21/1997
• Status: Expired due to Fees

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Baney, Douglas M.
• Primary Examiner(s): NGO, HUNG NHAT
• Application Number:
  US08/976,187
• Time in Patent Office: 781 Days
• Field of Search: 359/130, 385/46, 385/24, 385/37, 385/15, 385/10
• US Class Current: 385/24
• CPC Class Codes: G02B 6/29319 With a cascade of diffractive elements or of diffraction operations forming interferometer by splitting and recombining G02B6/29347 - G02B6/29358
• CPC Class Codes: G02B 6/29322 Diffractive elements of the tunable type G02B6/02195 takes precedence; optical modulation devices based on a change of the optical properties of the medium G02F1/00
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems
• CPC Class Codes: H04Q 11/0005 Switch and router aspects
• CPC Class Codes: H04Q 2011/0009 using wavelength filters
• CPC Class Codes: H04Q 2011/0022 using fibre gratings

Abstract

A channel selection method and apparatus accommodate the dynamic reconfiguration of channels that are passed through parallel waveguides by selectively tuning Bragg gratings along the waveguides. In the preferred embodiment, the waveguides are output optical fibers connected to an optical splitter having an input of a wavelength division multiplexed (WDM) optical signal. The number of channels in the WDM signal is equal to the number of output fibers, which is in turn equal to the number of tunable Bragg gratings along each of the output fibers. The series of Bragg gratings on a particular output fiber is structurally identical to the other series, with each tunable Bragg grating being dedicated to passing or rejecting one of the channels of the WDM signal. Thus, the series of Bragg gratings along a particular output fiber may be tuned to isolate any of the channels or may be tuned to pass two or more channels. In addition to use in a demultiplexing application, the method and apparatus may be used in a multiplexing application to enable channel selection along each of a number of different input waveguides.

Claims

1. An optical selector comprising:

a plurality of bidirectional first optical waveguides, each first optical waveguide having a plurality of first Bragg gratings that are tunable with respect to selectively defining wavelength bands of low transmissivity;

N bidirectional second optical waveguides, N being a number greater than one, said second optical waveguides including generally identical configurations of M second Bragg gratings that are tunable with respect to selectively defining wavelength bands of low transmissivity;

a bidirectional coupler optically coupling said first and second optical waveguides for enabling bidirectional optical transmissions between each of said first optical waveguides and each of said N second optical waveguides; and

at least one Bragg grating tuner connected to independently manipulate said tunable first and second Bragg gratings.

2. The optical selector of claim 1 wherein the number of second optical waveguides, N, is equal to the number of second Bragg gratings along each second optical waveguide, M.

3. The optical selector of claim 2 wherein each said first and second optical waveguide is connected to receive a wavelength division multiplexed (WDM) signal having a number of channels equal to N, said coupler being configured to continuously couple each of said first optical waveguides to each of said second optical waveguides.

4. The optical selector of claim 3 wherein each of said M Bragg gratings is tunable and a first said Bragg grating tuner is operatively associated with each of said tunable second Bragg gratings for independently manipulating said tunable second Bragg gratings.

5. The optical selector of claim 1 wherein each said second optical waveguide is connected to a first source of WDM signals having M channels, where M is equal to N, each of said second M Bragg gratings being tunable.

6. The optical selector of claim 5 wherein each said first optical waveguide is connected to a second source of WDM signals having M channels, said at least one Bragg grating tuner being operatively associated with said tunable first and second Bragg gratings for independently manipulating said tunable first and second Bragg gratings.

7. A method for isolating optical carriers in an optical selector having pluralities of first bidirectional waveguides and second bidirectional waveguides comprising the steps of:

providing a plurality of tunable first filter gratings along each first waveguide;

inputting first optical signals having a plurality of optical carriers into first ends of each said first waveguide;

splitting optical energy of said first optical signals at second ends of said first waveguides, thereby forming a plurality of split first optical signals;

routing said split first optical signals into said plurality of second waveguides;

selectively tuning said wavelength tunable first filter gratings such that said routed split first optical signals are a selected arrangement of target optical carriers;

providing a plurality of tunable second filter gratings along each said second waveguide;

inputting second optical signals having a plurality of optical carriers into first ends of said second waveguides;

splitting optical energy of said second optical signals at second ends of said second waveguides, thereby forming a plurality of split second optical signals;

routing said split second optical signals to said plurality of first waveguides; and

selectively tuning said tunable second filter gratings such that said routed split second optical signals are a selected arrangement of target optical carriers.

8. The method of claim 7 wherein said step of providing said plurality of tunable first filter gratings along each said first waveguide is a step of providing an identical arrangement of wavelength tunable filter gratings along each of said first waveguides.

9. The method of claim 8 wherein said step of providing said plurality of tunable first filter gratings includes establishing a one-to-one correspondence between said wavelength tunable first filter gratings along each of said first waveguides and said plurality of optical carriers of said first optical signals.

10. The method of claim 7 wherein said step of tuning said wavelength tunable first filter gratings is implemented such that each plurality of first filter gratings passes only one optical carrier of said first plurality of optical carriers.