The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 06, 1979
Filed:
Sep. 27, 1976
Vellayan Ramaswamy, Lincroft, NJ (US);
Robert D Standley, Shrewsbury, NJ (US);
Bell Telephone Laboratories, Incorporated, Murray Hill, NJ (US);
Abstract
Optical signal processing devices, primarily intended for use in integrated optical communication systems, include 3 dB coupled strip guide directional couplers. Each coupler is formed in a body of electrooptic material and includes electrodes bracketing at least one of the guides in the coupled region. Each coupler is fabricated so as to be overcoupled (i.e., greater than 3 dB coupling) when the coupling is synchronous. Voltage bias, supplied to the electrodes of each coupler, produces sufficient asynchronism to independently adjust each coupler to the desired 3 dB coupling condition. Permutation switches are produced by including a switchable phase shifter between two couplers. Channel drop filters are produced by including reflection gratings between two couplers. Differential phase detectors, for a pulse code modulation system, are produced by including a selected path length difference between the two strip guides connecting two couplers. A photolithographic technique for producing the required electrodes in precise registry with the strip guide couplers (typically characterized by 3 micrometer spacings) includes the use of the primary strip guide mask and a secondary mask to produce a photolithographic mask for defining the electrodes.