US 2017/0012705 A1Published application

Stabilized microwave-frequency source

AssigneesCalifornia Institute of Technology, Government of the United States of America as Represented by the Secretary of Commerce, The Nati

InventorsKerry VAHALA, Scott DIDDAMS, Jiang LI, Xu YI, Hansuek LEE

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Abstract

A microwave-frequency source at frequency fM comprises: a dual optical-frequency reference source, an electro-optic sideband generator, an optical bandpass filter, an optical detector, a reference oscillator, an electrical circuit, and a voltage-controlled oscillator (VCO). The sideband generator modulates dual optical reference signals at v2 and v1 to generate sideband signals at v1±n1fM and v2±n2fM. The bandpass filter transmits sideband signals at v1+N1fM and v2−N2fM. The optical detector generates a beat note at (v2−N2fM)−(v1+N1fM). The beat note and a reference oscillator signal are processed by the circuit to generate a loop-filtered error signal to input to the VCO. Output of the VCO at fM drives the sideband generator and forms the microwave-frequency output signal. The resultant frequency division results in reduced phase noise on the microwave-frequency signal.

Claims47

Dependent claims

A microwave-frequency source for generating an output electrical signal at an output frequency fM, the microwave-frequency source comprising:

(a) a voltage-controlled electrical oscillator arranged so as to generate a VCO output electrical signal at the frequency fM, a first portion of which forms the output electrical signal of the microwave-frequency source;
(b) a dual optical-frequency reference source arranged so as to generate (i) a first optical reference signal at a first optical reference frequency v1 and (ii) a second optical reference signal at a second optical reference frequency v2>v1;
(c) an electro-optic sideband generator arranged so as to (i) receive a second portion of the VCO output electrical signal at the frequency fM, (ii) receive the first optical reference signal and generate therefrom a first set of multiple sideband optical signals at respective sideband optical frequencies centered at v1 and spaced by fM, and (iii) receive the second optical reference signal and generate therefrom a second set of multiple sideband optical signals at respective sideband optical frequencies centered at v2 and spaced by fM;
(d) an optical bandpass filter arranged so as to transmit at least one sideband optical signal from the first set and at least one sideband optical signal from the second set;
(e) an optical detector arranged so as to (i) receive the transmitted sideband optical signals and (ii) generate an optical detector electrical signal at a beat frequency that is a difference between the corresponding sideband optical frequencies of one transmitted sideband optical signal of the first set and one transmitted sideband optical signal of the second set;
and
(f) an electrical circuit arranged so as to (i) generate an electrical error signal dependent on relative phase of the optical detector electrical signal and a reference oscillator electrical signal, and (ii) couple the voltage-controlled oscillator and the electro-optic sideband generator in a negative feedback arrangement based on the electrical error signal.

4 more elements

A method for generating a microwave-frequency output electrical signal at an output frequency fM, the method comprising:

(a) using a voltage-controlled electrical oscillator, generating a VCO output electrical signal at the frequency fM, a first portion of which forms the output electrical signal of the microwave-frequency source;
(b) using a dual optical-frequency reference source, generating (i) a first optical reference signal at a first optical reference frequency v1 and (ii) a second optical reference signal at a second optical reference frequency v2>v1;
(c) using an electro-optic sideband generator, (i) receiving a second portion of the VCO output electrical signal at the frequency fM, (ii) receiving the first optical reference signal and generating therefrom a first set of multiple sideband optical signals at respective sideband optical frequencies centered at v1 and spaced by fM, and (iii) receiving the second optical reference signal and generating therefrom a second set of multiple sideband optical signals at respective sideband optical frequencies centered at v2 and spaced by fM;
(d) using an optical bandpass filter, transmitting at least one sideband optical signal from the first set and at least one sideband optical signal from the second set;
(e) using an optical detector, (i) receiving the transmitted sideband optical signals and (ii) generating an optical detector electrical signal at a beat frequency that is a difference between the corresponding sideband optical frequencies of one transmitted sideband optical signal of the first set and one transmitted sideband optical signal of the second set;
and
(f) using an electrical circuit, (i) generating an electrical error signal dependent on relative phase of the optical detector electrical signal and a reference oscillator electrical signal, and (ii) coupling the voltage-controlled oscillator and the electro-optic sideband generator in a negative feedback arrangement based on the electrical error signal.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 15/235,075Filed 11 Aug 2016
Priority: 24 Jan 2014
Published: 12 Jan 2017
Term ends: Not estimatedThe source records don’t support an estimate.

Classification14 codes

H04B 10/2507
Arrangements specific to fibre transmission: for the reduction or elimination of distortion or dispersion
H03B 17/00
Generation of oscillations using radiation source and detector
H03L 7/08
Using a reference signal applied to a frequency- or phase-locked loop: details of the phase-locked loop
H03L 7/16
Using a reference signal applied to a frequency- or phase-locked loop: indirect frequency synthesis, i.e. generating a desired one of a number of…

Family

Application61/931,060Us provisional application · filed 24 Jan 2014
Application61/982,749Us provisional application · filed 22 Apr 2014
Application14/605,977Continuation · filed 26 Jan 2015
Application15/235,075Continuation
US 10,009,103 B2Related patent
US 2015/0236784 A1Published application
US 9,450,673 B2Related patent
US 2017/0012705 A1This patent

From the US filing history. Foreign family members aren’t listed.