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

• US 7,567,376 B2
• Filed: 07/11/2008
• Issued: 07/28/2009
• 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:
  US12/171,780
• Publication Number:
  US 20080273558A1
• Time in Patent Office: 382 Days
• Field of Search: 359/333, 359/341.1
• 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. Moreover, 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 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 pulse selector comprising an integrated modulator, the first pulse selector being coupled to a second output of the polarization-maintaining device, said pulse selector being disposed downstream of said pulse stretcher and configured to receive stretched pulses;

a fiber amplifier coupled to an output of the first pulse selector; and

a second pulse selector comprising an integrated modulator, the second pulse selector being coupled to the fiber amplifier, wherein at least one of an input and output of each of the first and second pulse selectors is fiber coupled.

2. The chirped pulse amplification system according to claim 1, wherein the pulse stretcher comprises:

a linearly chirped fiber grating; and

a Faraday rotator.

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

a non-linearly chirped fiber grating; and

a Faraday rotator.

4. The chirped pulse amplification system according to claim 1, wherein the first pulse selector comprises an electra-optic modulator or an electro-absorption modulator.

5. The chirped pulse amplification 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.

6. The chirped pulse amplification 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 at that port of the polarization-maintaining beam router in case the optical device is transmissive.

7. The chirped pulse amplification system according to claim 1, wherein the fiber amplifier comprises double clad multimode amplifier fiber operating as a single mode amplifier.

8. The chirped pulse amplification system according to claim 1, wherein the fiber 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.

9. The chirped pulse amplification system of claim 1, wherein an increase in pulse width produced with the stretcher sufficiently reduces the peak intensity of a pulse such that non-linear effects within the first and second pulse selectors and corresponding integrated modulators are substantially avoided.

10. The chirped pulse amplification system according to claim 1, wherein the second pulse selector comprises an integrated electro-absorption modulator.

11. The chirped pulse amplification system according to claim 1, wherein the chirped pulse amplification system comprises an operating wavelength at about 1550 nanometers or 1060 nanometers.

12. The chirped pulse amplification system according to claim 1, wherein one or both of the first and second pulse selectors comprise cascaded integrated and synchronized modulators, the modulators providing a contrast ratio of at least 30 dB.

13. The chirped pulse amplification system according to claim 1, wherein the fiber amplifier comprises a erbium doped or ytterbium/erbium doped gain fiber.