Photonic Based Cross-Correlation Homodyne Detection with Low Phase Noise

• US 20090208205A1
• Filed: 11/13/2008
• Published: 08/20/2009
• Est. Priority Date: 11/13/2007
• Status: Active Grant

• Current Assignee: Oewaves Incorporated
• Original Assignee: Oewaves Incorporated
• Inventors: Maleki, Lute, Eliyahu, Danny, Morozov, Nikolai
• Granted Patent: US 8,155,913 B2
• Time in Patent Office: Days
• US Class Current: 398/25
• CPC Class Codes: G01R 31/2824 testing of oscillators or resonators
• CPC Class Codes: H04B 10/61 Coherent receivers
• CPC Class Codes: H04B 10/63 Homodyne , i.e. coherent receivers where the local oscillator is locked in frequency and phase to the carrier signal

Abstract

In one aspect, this document provides an implementation of a system for characterizing an oscillator. This system includes an input port that receives an oscillation signal from an oscillator under test; an input port signal splitter that splits the received oscillation signal into a first oscillation signal and a second oscillation signal; a first photonic signal processing branch circuit that processes the first oscillation signal to produce a first branch output signal; a second photonic signal processing branch circuit that processes the second oscillation signal to produce a second branch output signal; a dual channel signal analyzer that receives the first and second branch output signals to measure noise in the received oscillation signal; and a computer controller that controls the first and second photonic signal processing branch circuits and the dual channel signal analyzer to control measurements of the noise in the received oscillation signal.

Claims

1. A system for characterizing an oscillator, comprising:

an input port that receives an oscillation signal from an oscillator under test;

an input port signal splitter that splits the received oscillation signal into a first oscillation signal and a second oscillation signal;

a first photonic signal processing branch circuit that processes the first oscillation signal to produce a first branch output signal;

a second photonic signal processing branch circuit that processes the second oscillation signal to produce a second branch output signal;

a dual channel signal analyzer that receives the first and second branch output signals to measure noise in the received oscillation signal; and

a computer controller that controls the first and second photonic signal processing branch circuits and the dual channel signal analyzer to control measurements of the noise in the received oscillation signal.

2. The system as in claim 1, wherein:

the first photonic signal processing branch circuit comprises;

a first signal splitter to splits the first oscillation signal into a first branch signal and a second branch signal;

a photonic branch that receives the first branch signal and comprises a laser that produces a laser beam, an optical modulator that modulates the laser beam in response to the first branch signal to produce a modulated laser beam that carries the first branch signal, an optical delay unit that transmits the modulated laser beam to produce a delay in the modulated laser beam, and an optical detector that converts the modulated laser beam into a detector signal;

an electrical branch that receives the second branch signal and comprises a voltage controlled phase shifter that receives the second branch signal and to changes a phase of the second branch signal to produce an output signal; and

a signal mixer that mixes the detector signal and the output signal to produce the first branch output signal.

3. The system as in claim 2, wherein:

the optical delay unit comprises a fiber delay line.

4. The system as in claim 2, wherein:

the voltage controlled phase shifter is under a control of the computer controller.

5. The system as in claim 4, wherein:

the computer controller controls the voltage controlled phase shifter to set a phase of the signal mixer at a quadrature condition.