Northrop Grumman Systems Corporation

Wenshen Wang

David C Scott

Elizabeth Twyford Kunkee

David V Forbes

Timothy A Vang

Thomas Jin-Ming Jung

Joseph Morais

The present photonic RF generation and distribution system provides a system and method for distributing an RF output signal. The photonic RF distribution system includes two optical sources for generating optical signals. A first optical source () is operable to generate a first optical signal having an operating frequency. A second optical source () is operable to generate a second optical signal having an operating frequency. A modulator () is operable to impress an RF modulation signal on a tapped portion of the first optical signal such that a modulated signal is generated. A first coupler () combines the modulated signal with a tapped portion of the second optical signal, thereby forming a combined signal having a difference frequency component. A control photodetector () is responsive to the combined signal to generate a tone signal. An offset locking circuit (), responsive to the tone signal, controls the operating frequency of the optical sources (and) such that the first optical signal and the second optical signal are frequency locked.

Photonic RF distribution system

A PIN electro-optical traveling wave modulator () including diffraction gratings () positioned at opposing sides of an optical waveguide () that act to change the propagation pattern of the waveguide (). The modulator () includes an N-type layer (), a P-type layer () and an intrinsic layer () acting as the waveguide (). A metal electrode () is in electrical contact with the N-type layer (), and a metal electrode () is in electrical contact with the P-type layer (). The electrodes () define an RF transmission line. An optical wave () propagates along the waveguide () and interacts with the gratings () which slow the optical wave () to match its speed to the speed of the RF wave in the transmission line. In one embodiment, the gratings () are 2-D gratings formed by vertical holes () in the waveguide ().

Slow wave optical waveguide for velocity matched semiconductor modulators

A coupled quantum well Mach-Zehnder modulator that employs a push-pull structure to reduce the modulation voltage. The Mach-Zehnder modulator includes a first arm having a first PIN semiconductor device and a second arm having a second PIN semiconductor device. The intrinsic layers of the PIN devices include a coupled quantum well structure to provide an opposite index of refraction change for different DC bias voltages. An RF signal used to modulate the light beam is applied to the two arms in phase and causes the index of refraction in the intrinsic layers of the two PIN devices to change in opposite directions so that a push-pull type drive is achieved without requiring 180&#xb0; out-of-phase RF drive signal.

Growing community of inventors

Torrance, CA, United States of America

Wenshen Wang