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. 03, 1998
Filed:
Feb. 27, 1996
Michael J LaGasse, Seattle, WA (US);
The Boeing Company, Seattle, WA (US);
Abstract
A phase-modulated fiber optic communication link (9) with carrier signal filtering is disclosed. The phase-modulated fiber optic communication link (9) includes a laser (11) that produces a optical carrier signal that is conveyed by an optical fiber (13) to a phase modulator (15). A modulated RF signal phase modulates the optical carrier signal and produces a phase-modulated signal comprising a carrier component (27), an upper sideband (29), and a lower sideband (31). The upper and lower sidebands are out of phase by 180 degrees. The phase-modulated signal is conveyed by an optical fiber to a delay line filter (21). In one embodiment of the invention, the delay line filter (21) attenuates the power of the optical carrier signal and passes the sidebands substantially unattenuated. One of the sidebands is phase shifted by 180 degrees by the delay line filter. The output of the delay line filter is applied to a photodiode detector (23), which recovers the RF modulated signal. In an alternative embodiment of the invention, the delay line filter (76) divides the phase-modulated signal into two signals, each containing a part of the optical carrier signals and one of the sidebands. One of the two signals is phase shifted with respect to the other signal, whereby the sidebands contained in the two signals are in phase. The signals are applied to two photodiodes (88, 89) whose outputs are combined in a differential detector (90) resulting in the recovery of the RF modulated signal.