WDM optical communication systems with wavelength-stabilized optical selectors

• US 6,341,025 B1
• Filed: 01/08/2001
• Issued: 01/22/2002
• Est. Priority Date: 02/23/1996
• Status: Expired due to Term

• Current Assignee: Ciena Corporation
• Original Assignee: Ciena Corporation
• Inventors: Mizrahi, Victor, Harmon, Stephen R.
• Primary Examiner(s): NEGASH, KINFE MICHAEL
• Application Number:
  US09/756,159
• Time in Patent Office: 379 Days
• Field of Search: 359/130, 359/124, 385/37, 356/345
• US Class Current: 398/87
• CPC Class Codes: G02B 6/02204 using thermal effects, e.g. heating or cooling of a temperature sensitive mounting body optical modulation using thermo-optic effect G02F1/0147
• 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 6/2932 comprising a directional router, e.g. directional coupler, circulator
• 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: G02B 6/29356 Interference cavity within a single light guide, e.g. between two fibre gratings G02B6/29347 - G02B6/2935 take precedence; evanescent coupling to a resonator cavity G02B6/29335
• CPC Class Codes: G02B 6/29361 Interference filters, e.g. multilayer coatings, thin film filters, dichroic splitters or mirrors based on multilayers, WDM filters
• CPC Class Codes: G02B 6/2938 for multiplexing or demultiplexing, i.e. combining or separating wavelengths, e.g. 1xN, NxM
• CPC Class Codes: G02B 6/29395 configurable, e.g. tunable or reconfigurable switching G02B6/35
• CPC Class Codes: G02B 6/29398 Temperature insensitivity
• CPC Class Codes: G02B 6/4246 Bidirectionally operating package structures
• CPC Class Codes: H01S 5/0687 Stabilising the frequency of the laser
• CPC Class Codes: H01S 5/4025 Array arrangements, e.g. constituted by discrete laser diodes or laser bar H01S5/42 takes precedence
• CPC Class Codes: H04B 10/505 using external modulation
• CPC Class Codes: H04B 10/5057 using a feedback signal generated by analysing the optical output
• CPC Class Codes: H04B 10/506 Multiwavelength transmitters
• CPC Class Codes: H04B 10/572 Wavelength control
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems

Abstract

The present invention provides a wavelength division multiplexed optical communication system with dynamically stabilized wavelength selectors. To accurately correlate the wavelength of a wavelength selector to the wavelength emitted by an optical transmission source, the present invention uses an optical detector and feedback loop to optimize the wavelength of an optical selection element in accordance with a wavelength of an incident optical channel. In one embodiment, the optical selection element is a Bragg grating associated with a grating wavelength controller, such as a temperature regulator or strain tuning system, to adjust the wavelength band of maximum reflectivity of the grating. The feedback loop communicates with the optical detector and the wavelength controller to modify the grating'"'"'s reflection wavelength band in accordance with the wavelength of an incident optical channel.

Claims

1. An optical device comprising:

a Bragg grating for coupling to an optical waveguide, said Bragg grating having an optical wavelength characteristic and interacting with light transmitted along said optical waveguide;

an optical tap having an input and first and second outputs, said input of said optical tap being coupled to said Bragg grating;

a detector coupled to said first output of said optical tap, said detector generating a sense signal in response to a first portion of said interacted light;

a control element coupled to said detector and said Bragg grating, said control element adjusting said wavelength characteristic in response to said sense signal; and

a receiver circuit coupled to said second output of said optical tap, said receiver being configured to receive a second portion of said interacted light.

2. An optical device in accordance with claim 1, wherein said control element further comprises:

a strain adjustment element coupled to said Bragg grating; and

a regulator circuit having an input receiving said sense signal, and an output coupled to said strain adjustment element for controlling a strain on said Bragg grating in response to said sense signal.

3. An optical device in accordance with claim 1, wherein said detector is coupled to said optical waveguide to sense light reflected from said Bragg grating.

4. An optical device in accordance with claim 1, wherein said detector is coupled to said optical waveguide to sense light transmitted through said Bragg grating.

5. An optical device in accordance with claim 1, wherein said control element further comprises:

a temperature adjustment circuit coupled to said Bragg grating; and

a regulator circuit having an input receiving said sense signal, and an output coupled to said temperature adjustment element for controlling a temperature of said Bragg grating in response to said sense signal.