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:
Jul. 02, 1996
Filed:
Jun. 06, 1995
Robert R Hayes, Calabasas, CA (US);
William B Bridges, Pasadena, CA (US);
Hughes Aircraft Company, Los Angeles, CA (US);
Abstract
A circuit and method for actively stabilizing the DC bias voltages applied to passive sections of a linearized directional coupler modulator. A reference electrical signal is applied to the active section of a linearized directional coupler modulator, thereby modulating an input optical beam. An optical detector is used at the output end of the modulator to monitor the modulated optical beam. The output of the detector is sent to one or more synchronous detectors that select the one or more harmonic frequency components that one wants to suppress. The synchronous detector output is sent to a filter that converts the harmonic frequency component to a DC bias voltage, which is integrated and used to bias the passive section of the modulator. The resulting negative-feedback loop minimizes the magnitude of the particular harmonic that is selected by the filter. In a preferred embodiment, the present stabilization circuit is used to stabilize the bias voltages in a three-section linearized directional coupler modulator, resulting in a stable modulator with low second harmonic distortion and low third-order intermodulation distortion.