Frequency tuning of photonic oscillator using amplifier bias voltage

• US 7,457,489 B2
• Filed: 01/04/2006
• Issued: 11/25/2008
• Est. Priority Date: 09/16/2003
• Status: Expired due to Fees

• Current Assignee: HRL Laboratories LLC (The Boeing Co.)
• Original Assignee: HRL Laboratories LLC (The Boeing Co.)
• Inventors: Sayyah, Keyvan
• Primary Examiner(s): Kianni; K. Cyrus
• Application Number:
  US11/325,913
• Publication Number:
  US 20060239695A1
• Time in Patent Office: 1,056 Days
• Field of Search: 385/14, 385/15, 385/3, 398/193
• US Class Current: 385/14
• CPC Class Codes: G02F 1/0121 Operation of devices; Circuit arrangements, not otherwise provided for in this subclass
• CPC Class Codes: H03B 17/00 Generation of oscillations using radiation source and detector, e.g. with interposed variable obturator
• CPC Class Codes: H03L 7/099 concerning mainly the controlled oscillator of the loop

Abstract

In one implementation, a method is provided for frequency tuning of a photonic oscillator. The method includes supplying an optical signal, for example laser light, which is modulated, delayed, and then converted to an electrical signal. The electrical signal is amplified, and used in modulating the optical signal. With this implementation, the frequency of the an output signal of the photonic oscillator is shifted by adjusting a bias voltage of the amplifier. In some implementations, shifting the frequency of the output signal further includes using a frequency lock loop circuit. In some implementations, shifting the frequency of an output signal of the photonic oscillator further comprises adjusting at least one of an phase shifter in series with the amplifier, an optical fiber stretcher, or a bias voltage of a second amplifier.

Claims

1. A method for frequency tuning of a photonic oscillator comprising:

a) supplying an optical signal;

b) modulating the optical signal;

c) delaying the modulated optical signal;

d) converting the modulated optical signal to an electric signal after delaying the optical signal;

e) amplifying the electric signal;

f) wherein modulating the optical signal comprises using the electric signal after amplifying; and

g) shifting a frequency of an output signal of the photonic oscillator by adjusting a bias voltage of a first amplifier amplifying the electric signal.

2. The method of claim 1 wherein shifting the frequency of the output signal of the photonic oscillator further comprises using a frequency lock loop circuit.

3. The method of claim 2 wherein delaying the modulated optical signal comprises passing a portion of the optical signal through a long loop delay path and a portion of the modulated optical signal through a short loop delay path.

4. The method of claim 1 wherein delaying the modulated optical signal comprises passing a portion of the modulated optical signal through a long loop delay path and a portion of the modulated optical signal through a short loop delay path.

5. The method of claim 4 further comprising:

a) selecting a tone from a multi-tone output signal;

b) dividing a frequency of the selected tone;

c) providing a low frequency reference signal; and

d) locking the frequency of the tone after dividing, to the low frequency reference signal by adjusting the bias voltage of the first amplifier.

6. The method of claim 4 wherein shifting the frequency of an output signal of the photonic oscillator further comprises adjusting at least one of (1) an electrical phase shifter in series with the first amplifier;

(2) an optical fiber stretcher;

or (3) a bias voltage of a second amplifier coupled in series with the first amplifier.

7. A method for frequency tuning of a photonic oscillator comprising:

a) providing an optical signal;

b) passing the optical signal through an optical delay path via a modulator;

c) producing an electrical signal from an output of the optical delay path;

d) amplifying the electrical signal using a first amplifier;

e) modulating the optical signal using the electrical signal from the first amplifier; and

f) adjusting a bias voltage of the first amplifier in response to an output signal of the photonic oscillator so as to shift a frequency of the output signal of the photonic oscillator.

8. The method of claim 7 wherein shifting the frequency of the output signal of the photonic oscillator further comprises using a frequency lock loop circuit.

9. The method of claim 8 wherein passing the optical signal through the optical delay comprises passing a portion of the optical signal through a long loop delay path and a portion of the optical signal through a short loop delay path.

10. The method of claim 9 wherein using the frequency lock loop circuit comprises:

a) selecting a tone from a multi-tone output signal;

b) dividing a frequency of the selected tone;

c) providing a low frequency reference signal; and

d) locking the frequency of the tone after dividing, to the low frequency reference signal by adjusting the bias voltage of the first amplifier.

11. The method of claim 10 wherein shifting the frequency of the output signal of the photonic oscillator further comprises adjusting at least one of:

(1) an electrical phase shifter in series with the first amplifier;

(2) an optical fiber stretcher;

or (3) a bias voltage of a second amplifier coupled in series with the first amplifier.

12. The method of claim 7 wherein passing the optical signal through an optical delay comprises passing a portion of the optical signal through a long loop delay path and a portion of the optical signal through a short loop delay path.

13. The method of claim 12 further comprising:

a) selecting a tone from a multi-tone electrical output signal;

b) dividing a frequency of the selected tone;

c) providing a fixed low frequency signal; and

d) locking the divided frequency of the selected tone with the fixed low frequency signal by adjusting the bias voltage of the first amplifier.

14. The method of claim 12 wherein shifting the frequency of an output signal of the photonic oscillator further comprises adjusting at least one of (1) an electrical phase shifter in series with the first amplifier;

(2) an optical fiber stretcher;

or (3) a bias voltage of a second amplifier coupled in series with the first amplifier.