Bae Systems Aerospace Electronics, Inc.

Tracor Aerospace Electronic Systems, Inc.

John T Gallo

The present invention provides a photonic local oscillator signal generator. The generator includes a plurality of waveguides fabricated in a single substrate. The waveguides are fabricated with a lateral separation that enables an evanescent tail of an optical mode field generated in one waveguide to overlap with an evanescent tail of an optical mode field generated in an adjacent waveguide. The overlap of the evanescent tails produce cross-coupling between the laser light generated in the adjacent waveguides. The generator uses a common pumping element to pump laser cavities of both of the waveguides. The use of a common pumping element and the cross-coupling produces phase locking between the laser light generated in the plurality of waveguides. As a result of the phase locking, mutual optical coherence between the laser light is achieved. The mutual optical coherence provides an interference signal upon photodetection. This interference signal is the offset between the center frequency of the laser light produced in the adjacent waveguides and serves as the local oscillator signal.

Photonic local oscillator signal generator and method for generating a local oscillator signal

An N-bit analog to digital converter for converting optical signals into digital form is disclosed. The converter comprises N optical signal channels, one channel for each significant bit of the N-bit digital representation of the optical signal. Each optical channel comprises optical waveguides and photodetectors for converting the optical signal into electronic signals. The sensitivity of the photodetectors in each channel varies from most significant to least significant bit in the digital conversion. The electronic signals drive high-speed switching devices, each of which is set to a different threshold depending on which bit of the digital conversion the switch delivers. There are N switching devices directly driven by the N photodetector channels yielding N digital bits representing the magnitude of the optical input signal.

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Lansdale, PA, United States of America

John T Gallo