High power fiber chirped pulse amplification system utilizing telecom-type components

• US 7,440,162 B2
• Filed: 05/17/2006
• Issued: 10/21/2008
• Est. Priority Date: 06/27/2003
• Status: Expired due to Fees

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Harter, Donald, Gu, Xinhua, Uehara, Yuzuru
• Primary Examiner(s): BOLDA, ERIC L
• Application Number:
  US11/434,902
• Publication Number:
  US 20070008611A1
• Time in Patent Office: 888 Days
• Field of Search: 359/333
• US Class Current: 359/333
• CPC Class Codes: H01S 3/0057 Temporal shaping, e.g. pulse compression, frequency chirping soliton generation and propagation G02F1/3513, H01S3/063 and H01S3/108
• CPC Class Codes: H01S 3/0085 Modulating the output, i.e. the laser beam is modulated outside the laser cavity
• 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 3/06754 Fibre amplifiers H01S3/06708 takes precedence
• CPC Class Codes: H01S 3/094003 the pumped medium being a fibre
• CPC Class Codes: H01S 3/0941 of a laser diode
• CPC Class Codes: H01S 3/1608 erbium
• CPC Class Codes: H01S 3/1618 ytterbium
• CPC Class Codes: H01S 3/2316 Cascaded amplifiers
• CPC Class Codes: H01S 3/2333 Double-pass amplifiers

Abstract

A chirped pulse amplifier (CPA) system having a mode-locked laser and a high-speed pulse selector, wherein the pulse selector modulates output pulses based upon an applied modulation voltage. A pulse selector may be an integrated electro-optic modulator, for example a LiNbO₃ modulator, or an electro-absorption modulator. Difficulties related to free-space alignment and operational stability of some prior designs are reduced or eliminated. Fiber coupling generally simplifies beam delivery and alignment. Some embodiments include an erbium fiber (or erbium-ytterbium) based CPA system operating at a wavelength of approximately 1550 nanometers. Similar performance can be obtained at other wavelengths, for example a 1.06 .micrometer Yb-doped fiber system. Moreever, high amplification and peak intensity at the output may be achieved while avoiding non-linear effects in the pulse selector, thereby providing for high intensity picosecond or femtosecond operation.

Claims

1. A fiber-based chirped pulse amplification system, comprising:

a mode-locked laser;

a polarization-maintaining device coupled to an output of the mode-locked laser;

a pulse stretcher coupled to a first output of the polarization-maintaining device;

a first amplifier coupled to the pulse stretcher;

a pulse selector comprising an integrated modulator coupled to the first amplifier; and

a second amplifier coupled through a beam splitter to a second output of the polarization-maintaining device,

wherein the pulse stretcher comprises;

a dispersive optical element, at least a portion thereof comprising an optical fiber, the element causing an increase in a width of a pulse prior to and after amplification of the pulse by the first amplifier; and

a Faraday rotator mirror, wherein the pulse selector is coupled between the first amplifier and the Faraday rotator mirror.

2. The system according to claim 1, wherein the dispersive element comprises:

a polarization-maintaining dispersion shifted fiber.

3. The system according to claim 1, wherein the pulse stretcher comprises:

a linearly chirped polarization-maintaining fiber grating; and

a Faraday rotator, wherein the pulse selector is coupled between the first amplifier and the Faraday rotator.

4. The system according to claim 1, wherein the pulse stretcher comprises:

a non-linearly chirped polarization-maintaining fiber grating; and

a Faraday rotator, wherein the pulse selector is coupled between the first amplifier and the Faraday rotator.

5. The system according to claim 1, wherein the first amplifier comprises:

an erbium doped fiber amplifier or a erbium/ytterbium doped fiber amplifier or a ytterbium doped fiber amplifier;

a wavelength division multiplexer; and

a diode pump.

6. The system according to claim 1, wherein the pulse selector comprises an integrated electro-optic modulator or an electro-absorption modulator.

7. The system according to claim 1, wherein the polarization-maintaining device comprises a polarization-maintaining beam router, wherein a fiber axis orientation of the input and output fibers matches the orientation of the polarization beam splitter.

8. The system according to claim 1, wherein the polarization-maintaining device comprises:

a polarization-maintaining beam router, wherein a fiber axis orientation of the input and output fibers matches the orientation of the polarization beam splitter;

a Faraday rotator disposed at a first port of the polarization-maintaining beam router, and a Faraday rotator mirror disposed in a common optical path with the beam router so as to receive and reflect at least one beam transmitted or reflected within the router.

9. The system according to claim 1, wherein the second amplifier comprises double clad multimode amplifier fiber operating as a single mode amplifier.

10. The system according to claim 1, wherein the second amplifier comprises double clad multimode amplifier fiber operating as a single mode amplifier, wherein the double clad multimode amplifier fiber core is less than or equal to 20 micrometers in diameter.

11. The system according to claim 1, wherein the dispersive element comprises:

a polarization-maintaining dispersion compensated fiber.

12. The system according to claim 1, wherein at least one of an input and output of the pulse selector is fiber coupled.

13. The chirped pulse amplification system of claim 1 wherein the increase in pulse width prior to amplification with the first amplifier sufficiently reduces the peak intensity of the pulse such that non-linear effects within the pulse selector are substantially avoided.

14. The system of claim 1 wherein a fiber amplifier operating wavelength is about 1550 nanometers or 1060 nanometers.

16. The system according to claim 1, wherein at least one of an input and output of the pulse selector is fiber coupled.

15. A chirped pulse amplification system comprising:

a mode-locked laser;

a polarization-maintaining device coupled to an output of the mode-locked laser;

a pulse stretcher coupled to a first output of the polarization-maintaining device;

an amplifier coupled to the pulse stretcher; and

a first pulse selector comprising;

an integrated modulator coupled to a second output of the polarization-maintaining device.

17. A chirped pulse amplification system comprising:

a mode-locked laser;

a polarization-maintaining device coupled to an output of the mode-locked laser;

a pulse stretcher optically coupled to the polarization-maintaining device;

at least one pulse selector comprising an integrated modulator, the at least one pulse selector receiving a pulse stretched by the pulse stretcher;

a fiber optic amplifier coupled to the pulse stretcher and to the at least one modulator, the amplifier amplifying a pulse subsequent to stretching.

18. The chirped pulse amplification system of claim 17 further comprising a compressor to reduce the pulse width of a stretched and amplified pulse.