Cavity stabilized laser drift compensation

• US 10,050,407 B1
• Filed: 07/12/2017
• Issued: 08/14/2018
• Est. Priority Date: 07/12/2017
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Fernandez, Javier H., Clatterbuck, Todd O., Price, Gabriel N., Daniele, Andrew N., Lackey, Michael S., Thai, Chon, Bibb, Darcy
• Primary Examiner(s): Park, Kinam
• Application Number:
  US15/647,772
• Time in Patent Office: 398 Days
• CPC Class Codes: G04F 5/14 using atomic clocks
• CPC Class Codes: H01S 3/0014 Monitoring arrangements not otherwise provided for photometry G01J1/00, e.g. G01J1/4257; radiation pyrometry G01J5/00; measuring coherence of light G01J9/00; measuring wavelength of light G01J9/00, e.g. G01J9/0246; measuring optical pulses G01J11/00; calorimetrically measuring power of laser beams G01K17/003
• CPC Class Codes: H01S 3/13 Stabilisation of laser output parameters, e.g. frequency or amplitude
• CPC Class Codes: H01S 3/1303 by using a passive reference, e.g. absorption cell H01S3/139 takes precedence
• CPC Class Codes: H01S 3/1304 by using an active reference, e.g. second laser, klystron or other standard frequency source H01S3/139 takes precedence; automatic control of electronic generators H03L7/00
• CPC Class Codes: H01S 3/1305 Feedback control systems
• CPC Class Codes: H01S 3/1307 Stabilisation of the phase
• CPC Class Codes: H01S 3/136 by controlling devices placed within the cavity
• CPC Class Codes: H01S 3/137 for stabilising of frequency
• CPC Class Codes: H01S 5/06817 Noise reduction
• CPC Class Codes: H01S 5/06825 Protecting the laser, e.g. during switch-on/off, detection of malfunctioning or degradation
• CPC Class Codes: H01S 5/0683 by monitoring the optical output parameters
• CPC Class Codes: H01S 5/0687 Stabilising the frequency of the laser

Abstract

Generally discussed herein are systems, devices, and methods for providing a frequency stabilized optical frequency comb, including frequency stabilizing the optical frequency comb to a laser that is frequency stabilized to an optical reference cavity, generating a low frequency electrical signal from the optical frequency comb, comparing the generated low frequency electrical signal to a reference low frequency electrical signal, determining an optical reference cavity drift based on the comparison, and then adjusting a frequency of the laser in response to the determined optical reference cavity drift.

Claims

1. A method for providing a frequency stabilized optical frequency comb, the method comprising:

frequency stabilizing the optical frequency comb to a laser that is frequency stabilized to an optical reference cavity;

generating a low frequency electrical signal from the optical frequency comb;

comparing the generated low frequency electrical signal to a reference low frequency electrical signal;

determining an optical reference cavity drift based on the comparison; and

then adjusting a frequency of the laser in response to the determined optical reference cavity drift.

2. The method of claim 1 further comprising using a Kalman filter to determine the optical reference cavity drift.

3. The method of claim 2 further comprising using the Kalman filter to estimate a clock time error and a clock oscillation period error.

4. The method of claim 3 further comprising using the Kalman filter to estimate all states associated with a second order drift model.

5. The method of claim 2 further comprising measuring a variance of at least one electrical component and providing the measured variance as a parameter to the Kalman filter.

6. The method of claim 2 further comprising adjusting a frequency of the laser at a first rate greater than the frequency of the low frequency electrical signal.

7. The method of claim 1 wherein generating the low frequency electrical signal includes generating a radio-frequency signal by optical division, and then generating the low frequency electrical signal based on the generated radio-frequency signal.

8. The method of claim 1 wherein the low frequency electrical signal and the reference electrical signal include a one pulse per second signal.

9. The method of claim 3 further comprising using an inner control loop to adjust a clock oscillation period error to zero.

10. The method of claim 9 further comprising using an outer control loop to adjust a clock time error to zero.

11. A system for providing a frequency stabilized optical frequency comb, the system comprising:

an optical frequency comb;

an optical reference cavity configured to receive a laser beam and provide a portion of the received laser beam to the optical frequency comb;

a frequency generation unit configured to generate a low frequency electrical signal from the optical frequency comb;

a controller configured to;

compare the generated low frequency electrical signal to a reference electrical signal;

determine an optical reference cavity drift based on the comparison; and

then adjust a frequency of the laser in response to the determined optical reference cavity drift.

12. The system of claim 11 wherein the controller is configured to implement a Kalman filter to estimate the optical reference cavity drift.

13. The system of claim 12 wherein the controller is configured to implement the Kalman filter to estimate a clock time error and a clock oscillation period error.

14. The system of claim 13 wherein the controller is configured to implement the Kalman filter to estimate all states associated with a second order drift model.

15. The system of claim 12 wherein the controller is configured to receive a measurement of a variance of at least one electrical component and provide the measurement of the variance as a parameter to the Kalman filter.

16. The system of claim 12 wherein the controller is configured to adjust a frequency of the laser at a first rate greater than the frequency of the low frequency electrical signal.

17. The system of claim 11 wherein the controller is configured to generate a radio-frequency signal, and then generate the low frequency electrical signal based on the generated radio-frequency signal.

18. The system of claim 11 wherein the low frequency electrical signal and the reference electrical signal include a one pulse per second signal.

19. The system of claim 13 further comprising an inner control loop to adjust a clock oscillation period error to zero.

20. The system of claim 19 further comprising an outer control loop to adjust a clock time error to zero.