Environmentally stable passively modelocked fiber laser pulse source

• US 8,548,014 B2
• Filed: 02/16/2012
• Issued: 10/01/2013
• Est. Priority Date: 12/20/1993
• Status: Expired due to Fees

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Fermann, Martin E., Harter, Donald J.
• Primary Examiner(s): NGUYEN, DUNG T
• Application Number:
  US13/398,198
• Publication Number:
  US 20120219020A1
• Time in Patent Office: 593 Days
• Field of Search: 372/6, 372/11, 372/18
• US Class Current: 372/6
• CPC Class Codes: H01S 3/067 Fibre lasers
• CPC Class Codes: H01S 3/08059 Constructional details of the reflector, e.g. shape mirrors in general G02B5/08; mountings for mirrors G02B7/18
• CPC Class Codes: H01S 3/1112 Passive mode locking
• CPC Class Codes: H01S 3/1115 using intracavity saturable absorbers
• CPC Class Codes: Y10T 29/49826 Assembling or joining

Abstract

The present invention is directed to providing an environmentally stable, ultra-short pulse source. Exemplary embodiments relate to passively modelocked ultra-short fiber lasers which are insensitive to temperature variations and which possess only negligible sensitivity to pressure variations. Further, exemplary embodiments can be implemented in a cost-effective manner which render them commercially practical in unlimited applications. Arbitrary fiber lengths (e.g., on the order of 1 millimeter to 1 kilometer, or greater) can be used to provide an ultra-short pulse with a cost-effective architecture which is commercially practical.

Claims

1. A passively modelocked laser comprising:

a laser energy generator having a cavity which includes;

a fiber gain medium for amplifying energy in the cavity, wherein said cavity comprises multiple sections of fiber having different magnitudes of group-velocity dispersion, said multiple sections of fiber, in combination, providing for increased energy of oscillating pulses;

a pair of reflectors which define an optical axis which passes through the fiber gain medium and supports a plurality of longitudinal modes;

a mode-locking mechanism that locks said longitudinal modes in phase to produce optical pulses at said laser, wherein said modelocking mechanism comprises a semiconductor saturable absorber in said cavity arranged to at least initiate mode locking; and

an output for laser energy generated within said cavity, said output generating ultra-short pulses.

2. The passively modelocked laser according to claim 1, wherein said gain medium comprises a section of highly-birefringent doped fiber.

3. The passively modelocked laser according to claim 2, wherein said modelocking mechanism operates with a non-linear phase delay and is arranged in such a way that a non-linear phase difference between polarization states is determined by the relative power between said polarization states.

4. The passively modelocked laser according to claim 1, wherein said passively modelocked laser is capable of generating output pulses at GHz repetition rates.

5. The passively modelocked laser according to claim 1, wherein a total length of said multiple sections of fiber is on the order of 1 mm to 1 km.

6. The passively modelocked laser according to claim 2, wherein said gain medium comprises a section of low-birefringent fiber.

7. The passively modelocked laser according to claim 6, wherein a total length of the low-birefringent fiber is on the order of eight to ten times shorter than a total length of the highly-birefringent fiber.

8. The passively modelocked laser according to claim 1, further comprising a tuning element located in said cavity and configured to change either an optical length of said cavity or a wavelength of the laser energy generated within said cavity.

9. The passively modelocked laser according to claim 8, wherein said tuning element comprises a fiber stretcher located in said cavity that is operable to change a repetition rate of said ultra-short pulses.

10. The passively modelocked laser according to claim 1, further comprising a compensator which reduces the effects of linear phase drifts of the gain medium.

11. The passively modelocked laser according to claim 10, wherein said compensator comprises at least one Faraday rotator mirror.

12. The passively modelocked laser according to claim 1, further comprising a pump light source configured to optically excite said fiber gain medium.