Laser based frequency standards and their applications

• US 9,036,971 B2
• Filed: 07/16/2014
• Issued: 05/19/2015
• Est. Priority Date: 10/17/2005
• Status: Expired due to Fees

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Fermann, Martin, Hartl, Ingmar
• Primary Examiner(s): Blevins, Jerry
• Application Number:
  US14/332,436
• Publication Number:
  US 20140328358A1
• Time in Patent Office: 307 Days
• Field of Search: 385/14, 385/15, 385/27, 385/122, 372/6, 372/18
• US Class Current: 385/122
• CPC Class Codes: G02F 1/3528 for producing a supercontinuum
• CPC Class Codes: G02F 1/3558 Poled materials, e.g. with periodic poling; Fabrication of domain inverted structures, e.g. for quasi-phase-matching [QPM]
• CPC Class Codes: G02F 1/365 in an optical waveguide structure G02F1/377, G02F1/395 take precedence
• CPC Class Codes: G02F 2203/56 Frequency comb synthesizer
• CPC Class Codes: H01S 2301/02 ASE (amplified spontaneous emission), noise; Reduction thereof
• CPC Class Codes: H01S 3/067 Fibre lasers
• CPC Class Codes: H01S 3/06716 Fibre compositions per se C03C13/04or doping with active elements lasing materials in general H01S3/14
• CPC Class Codes: H01S 3/1112 Passive mode locking

Abstract

Frequency standards based on mode-locked fiber lasers, fiber amplifiers and fiber-based ultra-broad bandwidth light sources, and applications of the same.

Claims

1. A fiber-based laser system, comprising:

a frequency comb laser source comprising a passively mode-locked fiber laser, said frequency comb laser characterized by having a pulse repetition rate, laser cavity, and carrier envelope offset phase slip (CEOP);

a modulator disposed downstream from said frequency comb laser source, said modulator connected to a frequency reference and configured to frequency shift an output of said frequency comb laser representative of the CEOP of said frequency comb laser and to generate a frequency shifted CEOP signal; and

a detector which receives said CEOP signal.

2. The fiber-based laser system according to claim 1, wherein said modulator comprises an acousto-optic device and said frequency comprises an RF reference frequency.

3. The fiber-based laser system according to claim 1, wherein said modulator is disposed external to said cavity.

4. The fiber-based laser system according to claim 1, wherein said frequency shift corresponds to a drive frequency of said modulator.

5. The fiber-based laser system according to claim 1, wherein a beat note related to the carrier envelope offset phase slip is frequency shifted by the frequency of the modulator.

6. The fiber-based laser system according to claim 5, wherein an RF filter is configured to provide separation from an intermode beat signal related to a pulse repetition frequency (PRF) at zero carrier envelope offset phase slip.

7. The fiber-based laser system according to claim 1, said fiber-based laser system further comprising:

a highly non-linear waveguide disposed downstream from said passively modelocked fiber laser, said highly non-linear waveguide capable of generating an octave spanning spectrum; and

an f-2f interferometer disposed downstream from said passively modelocked fiber laser and configured to stabilize said CEOP.

8. The fiber-based laser system according to claim 7, wherein said f-2f interferometer comprises a frequency converter, said frequency converter comprising a periodically poled non-linear crystal.

9. The fiber-based laser system according to claim 7, wherein said f-2f interferometer is configured with multiple optical paths, wherein said modulator is disposed in a first optical path, a frequency converter is disposed in a second optical path, and said frequency shifted CEOP signal from said modulator is combined with an output of said frequency converter and delivered to said detector.

10. The fiber-based laser system according to claim 7, wherein said low frequency part of the octave spanning spectrum is frequency doubled by a nonlinear crystal and combined with the high frequency part of said octave spanning spectrum which is frequency shifted by a modulator which is driven by a stable RF frequency.

11. The fiber-based laser system according to claim 1, wherein said fiber-based laser system comprises a highly non-linear waveguide disposed downstream from said passively modelocked fiber laser.

12. The fiber-based laser system of claim 11, wherein said highly non-linear waveguide comprises a positively dispersive Bismuth oxide based highly nonlinear fiber for spectral broadening.

13. The fiber-based laser system of claim 11, wherein said highly non-linear waveguide is based on a crystalline material.

14. The fiber-based laser system according to claim 11, wherein said highly non-linear waveguide comprises LiNbO₃, silicon, or a semiconductor material.

15. The fiber-based laser system according to claim 11, wherein said laser system comprises a supercontinuum generator which includes said highly non-linear waveguide.

16. The fiber-based laser system according to claim 1, wherein said frequency comb laser source comprises a highly non-linear waveguide disposed downstream from said passively mode locked fiber laser.

17. The fiber-based laser system according to claim 1, said system comprising a feedback control loop operatively connected to said frequency comb laser source in which said CEOP signal is utilized to stabilize said carrier envelope offset phase slip.

18. The fiber-based laser system according to claim 17, wherein said output comprises a beat signal corresponding to said CEOP, said beat signal being representative of a carrier envelope offset frequency.

19. The fiber-based laser system according to claim 17, wherein said carrier envelope offset phase is offset phase slip is stabilized to zero.

20. The fiber-based laser system according to claim 1, wherein said passively modelocked fiber laser generates pulses at a pulse repetition frequency, PRF, greater than about 110 MHz.

21. The fiber-based laser system according to claim 1, wherein said output comprises a beat signal corresponding to said CEOP, said beat signal being representative of a carrier envelope offset frequency.

22. A fiber-based laser system, comprising:

a passively mode locked fiber laser having a pulse repetition frequency, PRF, greater than about 110 MHz, wherein said passively modelocked fiber laser comprises a gain medium and an output of said passively mode locked fiber laser comprises a carrier envelope offset frequency, fceo, said passively mode locked fiber laser comprising an optical cavity having intra-cavity components disposed external to said gain medium configured to modify and stabilize said carrier envelope offset frequency, based on one or more signals representative of a variation of said carrier envelope offset frequency.

23. The laser system according to claim 22, said optical cavity having a net cavity dispersion, wherein said cavity is configured in such a way that the net cavity dispersion is substantially lower than the dispersion of any intra-cavity component.

24. The laser system according to claim 22, further comprising a fiber amplifier receiving outputs from said passively modelocked fiber laser and generating amplified pulses.

25. The laser system according to claim 22, further comprising a supercontinuum generator coupled to one of said fiber laser and said fiber amplifier.

26. The laser system according to claim 22, wherein said laser system comprises a highly non-linear waveguide disposed downstream from said passively modelocked fiber laser.

27. The laser system according to claim 22, further comprising an f-2f interferometer from which a signal representative of a variation of said carrier envelope offset frequency is derived, said interferometer arranged to measure and/or stabilize said carrier envelope offset frequency.

28. The laser system according to claim 22, wherein said intra-cavity components comprise a temperature controlled saturable absorber configured to modify and stabilize said carrier envelope offset frequency.

29. The laser system according to claim 22, wherein said intra-cavity components comprise a temperature controlled fiber Bragg grating configured to modify and stabilize said carrier envelope offset frequency.