Martin Marietta Corporation

Michael S Margulis

Thomas William Karras

Harvey L Wagner

An optical demultiplexer includes an electrooptic modulator (410) which modulates a beam of light (418) in response to frequency-multiplexed radio-frequency (RF) information signals, to produce diverging beamlets of light (420). The diverging beamlets are separated by a spatial separator arrangement (426), and each beamlet (420), including the information of its RF carrier, is coupled to a separate optical detector (428). The detector (428) can extract amplitude modulation from the signal. In order to reconstruct the RF signal as well as the amplitude modulator, an optical 'local oscillator' signal (OLO) is coupled to each detector together with its information signal. Signal loss due to vibration or misalignment is avoided, and heterodyne mixing efficiency is maximized in an embodiment of the invention, by propagating the OLO and information signals through a single-mode optical fiber to the detector. In a particular embodiment of the invention, the OLO signal is applied to a first fiber (622), the information signal is applied to a second fiber (610), and the first and second fibers are coupled together by a fiber-optic coupler (612). In another embodiment of the invention, the OLO signal results from generating an RF L.O. signal, and combining the RF L.O. local signal with the information signals before application to the electrooptic modulator, to generate an OLO beamlet (720) which is subject to the same vibration and misalignment as the signal beamlets.

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Yardley, PA, United States of America

Michael S Margulis