Wavelength division multiplexing methods and apparatus for constructing photonic beamforming networks

• US 6,828,934 B2
• Filed: 07/15/2002
• Issued: 12/07/2004
• Est. Priority Date: 06/14/2000
• Status: Expired due to Fees

• Current Assignee: HRL Laboratories LLC (The Boeing Co.)
• Original Assignee: HRL Laboratories LLC (The Boeing Co.)
• Inventors: Stephens, Ronald Regis
• Primary Examiner(s): PHAN, DAO LINDA
• Application Number:
  US10/196,444
• Publication Number:
  US 20020180637A1
• Time in Patent Office: 876 Days
• Field of Search: 342/368, 342/373, 342/374, 342/375
• US Class Current: 342/373
• CPC Class Codes: H01Q 3/2676 Optically controlled phased array
• CPC Class Codes: H04J 14/02 Wavelength-division multiplex systems
• CPC Class Codes: H04J 14/0307 Multiplexers; Demultiplexers

Abstract

Methods and apparatus for constructing phased array antenna beamforming networks are provided, that allow to scan multiple beams and select appropriate sets of delay lines simultaneously. The beamforming networks disclosed herein generate less losses than conventional ones and in some cases, do not require active switching, making them completely passive. Three main methods are comprised in the invention: (1) laser wavelength hierarchies, (2) arrangements of Wavelengths Division Multiplexing (WDM) components, (3) re-use of laser wavelengths. Multiple laser wavelengths are arranged in groups and subgroups (wavelength hierarchies) in the wavelength domain. By switching between these wavelength groupings, the arrangements of WDM components disclosed herein enable the beamforming network to direct the beam signals to the proper time delay lines, and to differentiate multiple beams. The method of laser wavelength re-use permits to significantly reduce the number of wavelengths utilized, and thus to limit them to the standard wavelengths specified by the ITU.

Claims

1. A method of beamforming comprising the steps of:

(a) synthesizing a plurality of optical wavefronts each comprising of plurality of optical wavelengths;

(b) receiving a plurality of incoming electrical wavefronts with an antenna;

(c) mixing said plurality of optical wavefronts with said plurality of incoming electrical wavefronts by optical modulation to provide a plurality of resultant optical wavefronts;

(d) directing each resultant optical wavefront to a predetermined set of delay lines; and

(e) separating each resultant optical wavefronts in order to direct each one to a different output.

2. The method of beamforming as in claim 1 wherein the step of synthesizing a plurality of optical wavefronts, includes the steps of:

(a) specifically selecting a subset of said plurality of optical wavelengths in accordance with the set of delay lines desired; and

(b) specifically selecting a subset of said plurality of optical wavelengths in accordance with the output desired.

3. The method of claim 2 wherein the step of directing each resultant optical wavefront to a predetermined set of delay lines, includes providing WDM filters capable of channeling each resultant optical wavefront into the predetermined delay line, by dispersing the wavelengths contained in each resultant optical wavefronts.