COMPACT FIBER SHORT PULSE LASER SOURCES

• US 20160248217A1
• Filed: 05/04/2016
• Published: 08/25/2016
• Est. Priority Date: 11/12/2013
• Status: Active Grant

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Fermann, Martin E.
• Granted Patent: US 9,819,141 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01S 2301/085 solitons
• CPC Class Codes: H01S 3/06712 Polarising fibre; Polariser
• CPC Class Codes: H01S 3/06725 Fibre characterized by a specific dispersion, e.g. for pulse shaping in soliton lasers or for dispersion compensating [DCF]
• CPC Class Codes: H01S 3/0675 Resonators including a grating structure, e.g. distributed Bragg reflectors [DBR] or distributed feedback [DFB] fibre lasers
• CPC Class Codes: H01S 3/1055 one of the reflectors being constituted by a diffraction grating
• CPC Class Codes: H01S 3/1067 using pressure or deformation
• CPC Class Codes: H01S 3/107 using electro-optic devices, e.g. exhibiting Pockels or Kerr effect H01S3/1061, H01S3/1063, H01S3/1065 take precedence
• CPC Class Codes: H01S 3/1112 Passive mode locking
• CPC Class Codes: H01S 3/1115 using intracavity saturable absorbers
• CPC Class Codes: H01S 3/1307 Stabilisation of the phase
• CPC Class Codes: H01S 3/161 holmium
• CPC Class Codes: H01S 3/1616 thulium

Abstract

Examples of robust self-starting passively mode locked fiber oscillators are described. In certain implementations, the oscillators are configured as Fabry-Perot cavities containing an optical loop mirror on one cavity end and a bulk mirror or saturable absorber on the other end. The loop mirror can be further configured with an adjustable line phase delay to optimize modelocking. All intra-cavity fiber(s) can be polarization maintaining. Dispersion compensation components such as, e.g., dispersion compensation fibers, bulk diffraction gratings or fiber Bragg gratings may be included. The oscillators may include a bandpass filter to obtain high pulse energies when operating in the similariton regime. The oscillator output can be amplified and used whenever high power short pulses are required. For example the oscillators can be configured as frequency comb sources or supercontinuum sources. In conjunction with repetition rate modulation, applications include dual scanning delay lines and trace gas detection.

Claims

1. A passively mode locked fiber oscillator evolving from Q-switching, comprising:

a Fabry-Perot cavity comprising;

a nonlinear fiber amplifying loop mirror (NALM) at a first cavity end, said nonlinear loop mirror configured to allow the insertion of a linear phase delay along two propagation directions of said nonlinear loop mirror,

wherein said passively mode locked fiber oscillator comprises polarization maintaining (PM) fiber.

2. The passively mode locked fiber oscillator according to claim 1, wherein mode locking of said oscillator evolves via suppression of Q-switching.

3. The passively mode locked fiber oscillator according to claim 1, wherein said loop mirror comprises:

an orthogonal splice configured to induce said phase delay, and

a temperature control device configured to control the temperature of a section of intra-loop fiber.

4. The passively mode locked fiber oscillator according to claim 3, further comprising:

a mirror, a saturable absorber, or a combination of a mirror with a saturable absorber at a second cavity end; and

a Faraday rotator inserted proximate to said second cavity end to compensate for a polarization rotation induced by said orthogonal splice.

5. The passively mode locked fiber oscillator according to claim 1, said linear phase delay being stabilized using feedback from the output power of the oscillator.

6. The passively mode locked fiber oscillator according to claim 1, said linear phase delay being used to control a carrier envelope offset frequency of said oscillator.

7. The passively mode locked fiber oscillator according to claim 1, said linear phase delay being induced using a non-reciprocal phase shifter.

8. The passively mode locked fiber oscillator according to claim 1, said fiber oscillator further comprising:

a bulk diffraction grating disposed in said cavity for dispersion control of said passively mode locked fiber oscillator.

9. The passively mode locked fiber oscillator according to claim 1, said fiber oscillator further comprising:

undoped positive dispersion fiber disposed in said cavity for dispersion control of said polarization maintaining passively mode locked fiber oscillator.

10. The passively mode locked fiber oscillator according to claim 1, said oscillator further comprising:

undoped negative dispersion photonic crystal fiber disposed in said cavity for dispersion control of said passively mode locked fiber oscillator.

11. The passively mode locked fiber oscillator according to claim 1, further comprising:

a narrow bandpass optical filter, wherein said oscillator generates a pulse bandwidth larger than the bandwidth of said optical filter.

12. The passively mode locked fiber oscillator according to claim 1, further comprising:

a mirror at a second cavity end, said mirror configured to allow modulation or scanning of the repetition rate of said oscillator in response to a control signal,

wherein said mode locked fiber oscillator is configured in a coherent dual scanning laser (CDSL) or coherent scanning laser (CSL) configuration.

13. The passively mode locked fiber oscillator according to claim 1, further comprising:

a mirror at a second cavity end, said mirror configured to allow modulation or scanning of the repetition rate of said oscillator in response to a control signal,

wherein said mode locked fiber oscillator is configured in a trace gas detection system which includes an enhancement cavity

14. The passively mode locked fiber oscillator according to claim 1, wherein said passively mode locked fiber oscillator is arranged in an all-PM configuration.

15. The passively mode locked fiber oscillator according to claim 1, wherein said Fabry-Perot cavity comprises a reflective optic at a second cavity end.

16. The passively mode locked fiber oscillator according to claim 15, wherein the reflective optic comprises a mirror, a saturable absorber, or a combination of a mirror with a saturable absorber.

17. The passively mode locked fiber oscillator according to claim 1, wherein the cavity further comprises an electro-optic modulator.

18. The passively mode locked fiber oscillator according to claim 1, wherein the cavity further comprises a loss modulator.

19. The passively mode locked fiber oscillator according to claim 18, wherein the loss modulator comprises a graphene modulator.

20. The passively mode locked fiber oscillator according to claim 1, wherein said NALM is configured as an optical limiting element.

21. The passively mode locked fiber oscillator according to claim 20, wherein said NALM optical limiting element is further configured to produce a fiber oscillator output with a root mean square intensity noise (RIN) less than −

140 dBc/Hz at least at one frequency in a range from 100 kHz to 1 MHz.

22. The passively mode locked fiber oscillator according to claim 1, configured as a frequency comb.

23. A passively mode locked fiber oscillator evolving from Q-switching, comprising:

a laser cavity comprising;

a nonlinear fiber amplifying loop mirror, said nonlinear loop mirror configured to allow the insertion of a linear phase delay along two propagation directions of said nonlinear loop mirror,

wherein said cavity is configured without any saturable absorber and is configured with polarization maintaining (PM) components in an all-PM or nearly all-PM configuration.

24. The passively mode locked fiber oscillator according to claim 23, wherein said loop mirror comprises:

an orthogonal splice configured to induce said linear phase delay, and

a temperature control device configured to control temperature of a section of intra-loop fiber.

25. The passively mode locked fiber oscillator according to claim 23, said linear phase delay being induced using a non-reciprocal phase shifter.

26. The passively mode locked fiber oscillator according to claim 23, wherein the cavity further comprises an electro-optic modulator.

27. The passively mode locked fiber oscillator according to claim 26, wherein said electro-optic modulator is configured to initiate modelocking of said mode locked fiber oscillator.

28. The passively mode locked fiber oscillator according to claim 23, wherein the cavity further comprises a loss modulator.

29. The passively mode locked fiber oscillator according to claim 28, wherein the loss modulator comprises a graphene modulator.