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:
Jun. 18, 1991
Filed:
Nov. 16, 1989
Pochi A Yeh, Thousand Oaks, CA (US);
John H Hong, Moorpark, CA (US);
Rockwell International Corporation, El Segundo, CA (US);
Abstract
Nonlinear optical devices and techniques are used to provide heterodyne detection for coherent optical communications. Heterodyne detection is achieved by matching the wave front of a local oscillator beam with the wave front of a received optical signal. Precise wave front matching provides high heterodyne efficiency and a wide field of view. In one embodiment, the received signal and a reference beam of the same frequency are directed into a nonlinear medium to form a volume hologram that contains the spatial information of the received signal. The reference beam is alternated with a local oscillator beam that has the same wave front and is parallel to the reference beam but at a different frequency. The hologram matches the wave fronts of the signal beam and the local oscillator beam to produce a large heterodyne signal. In an alternative embodiment, the received signal beam and the local oscillator beam are directed into a mutually pumped phase conjugator (MPPC). The MPPC generates a spatial phase conjugate of the oscillator beam that carries the temporal characteristics of the signal beam. A beam splitter combines the information carrying phase conjugate beam with a phase conjugate of the pure local oscillator beam returned by a phase conjugate mirror. The two phase conjugate beams arrive at the plane of a photodetector with precisely the same wave front and direction. The matched wave fronts produce high heterodyne efficiency, and the automatic tracking feature of the phase conjugators provides a wide field of view.