Compact, coherent, high brightness light sources for the mid and far IR

• US 9,252,554 B2
• Filed: 03/21/2014
• Issued: 02/02/2016
• Est. Priority Date: 02/14/2011
• Status: Expired due to Fees

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Fermann, Martin E.
• Primary Examiner(s): Zhang, Yuanda
• Assistant Examiner(s): CARTER, MICHAEL W
• Application Number:
  US14/221,704
• Publication Number:
  US 20140202994A1
• Time in Patent Office: 683 Days
• US Class Current: 1/1
• CPC Class Codes: B23K 26/352 for surface treatment
• CPC Class Codes: B23K 26/361 for deburring or mechanical trimming B23K26/351 takes precedence
• CPC Class Codes: B23K 26/362 Laser etching
• 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 3/06741 Photonic crystal fibre, i.e. the fibre having a photonic bandgap
• 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 3/06754 Fibre amplifiers H01S3/06708 takes precedence
• CPC Class Codes: H01S 3/06791 Fibre ring lasers fibre laser gyrometers G01C19/72
• CPC Class Codes: H01S 3/10015 by monitoring or controlling, e.g. attenuating, the input signal
• CPC Class Codes: H01S 3/10092 Coherent seed, e.g. injection locking
• CPC Class Codes: H01S 3/1112 Passive mode locking
• CPC Class Codes: H01S 3/1118 Semiconductor saturable absorbers, e.g. semiconductor saturable absorber mirrors [SESAMs]; Solid-state saturable absorbers, e.g. carbon nanotube [CNT] based
• CPC Class Codes: H01S 3/1608 erbium
• CPC Class Codes: H01S 3/1616 thulium

Abstract

Compact high brightness light sources for the mid and far IR spectral region, and exemplary applications are disclosed based on passively mode locked Tm fiber comb lasers. In at least one embodiment the coherence of the comb sources is increased in a system utilizing an amplified single-frequency laser to pump the Tm fiber comb laser. The optical bandwidth generated by the passively mode locked Tm fiber comb laser is further decreased by using simultaneous 2^nd and 3^rd order dispersion compensation using either appropriate chirped fiber Bragg gratings for dispersion compensation, or fibers with appropriately selected values of 2^nd and 3^rd order dispersion. Fibers with large anomalous values of third order dispersion, or fibers with large numerical apertures, for example fibers having air-holes formed in the fiber cladding may be utilized.

Claims

1. A fiber-laser based system, comprising;

a passively mode locked fiber oscillator comprising a gain fiber having an overall negative dispersion D2₁ (fs²);

at least one fiber section optically connected to said gain fiber and having a positive dispersion value D2₂ (fs²), wherein the absolute value of D2₂ is at least 1.5 times larger than the absolute value of D2₁;

a chirped fiber grating to compensate for the residual dispersion value of the oscillator, such that the overall cavity dispersion is in a range of about ±

20,000 fs² per meter cavity fiber length; and

a pump source to pump said passively mode locked fiber oscillator.

2. The fiber-laser based system according to claim 1, further comprising a highly nonlinear fiber operably arranged as a continuum fiber for super continuum generation.

3. The fiber-laser based system according to claim 2, further comprising a fiber amplifier inserted between said oscillator and said continuum fiber.

4. The fiber-laser based system according to claim 3, wherein said fiber amplifier is capable of higher order soliton compression, nonlinear compression, Raman soliton generation or chirped pulse amplification.

5. The fiber-laser based system according to claim 3, wherein said fiber amplifier is core pumped or cladding pumped.

6. The fiber-laser based system according to claim 3, further comprising a highly nonlinear silica fiber spliced directly to the output of said oscillator.

7. The fiber-laser based system according to claim 3, further comprising a highly nonlinear silica fiber spliced directly to the output of said fiber amplifier.

8. The fiber-laser based system according to claim 3, further comprising a large mode fiber amplifier (LMA) disposed downstream from said fiber amplifier.

9. The fiber-laser based system according to claim 2, further comprising an f-2f interferometer for carrier phase measurements.

10. The fiber-laser based system according to claim 9, wherein said f-2f interferometer is configured for carrier phase control of said oscillator.

11. The fiber-laser based system according to claim 1, wherein said oscillator is core pumped, and said pump source comprises:

a single-frequency laser; and

an Er fiber amplifier amplifying an output of said single-frequency laser.

12. The fiber-laser based system according to claim 1, wherein said oscillator comprises a saturable absorber.

13. The fiber-laser based system according to claim 1, wherein said oscillator is configured as a ring oscillator.

14. The fiber-laser based system according to claim 1, further comprising an extra-cavity acousto-optic frequency shifter for carrier envelope phase control.

15. A fiber-laser based system, comprising;

a passively mode locked fiber oscillator comprising a gain fiber having an overall negative dispersion, D2₁ (fs²);

at least one fiber section optically connected to said gain fiber and having a positive dispersion value D2₂ (fs²), wherein the length of said at least one fiber section is at least about 1.5 times larger than the length of the gain fiber;

a chirped fiber grating to compensate for the residual dispersion value of the oscillator, such that the overall cavity dispersion is in a range of about ±

20,000 fs² per meter of cavity fiber length; and

a pump source to pump said passively mode locked fiber oscillator.