John A Gallo

6434294, Aug 13, 2002

Sep 2, 1998

09/145908

John T. Gallo - Lansdale PA

BAE Systems Aerospace Electronics Inc. - Lansdale PA

G02B 634

385 27, 385 12, 385 15, 385 28, 385 30, 372 20, 372 64

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.

61883425, Feb 13, 2001

Nov 2, 1998

9/184666

John T. Gallo - Lansdale PA

Tracor Aerospace Electronic Systems, Inc. - Lansdale PA

H03M 100
H03M 112

341137

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.