Inexpensive variable rep-rate source for high-energy, ultrafast lasers

• US 8,248,690 B2
• Filed: 12/19/2008
• Issued: 08/21/2012
• Est. Priority Date: 05/14/2003
• Status: Expired due to Fees

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Harter, Donald J.
• Primary Examiner(s): BOLDA, ERIC L
• Application Number:
  US12/340,020
• Publication Number:
  US 20090097520A1
• Time in Patent Office: 1,341 Days
• Field of Search: 359/333, 359/341.1, 372/25
• US Class Current: 359/341.1
• CPC Class Codes: G02B 6/2932 comprising a directional router, e.g. directional coupler, circulator
• CPC Class Codes: G02B 6/29374 in an optical light guide G02B6/02214 takes precedence
• 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 3/067 Fibre lasers
• CPC Class Codes: H01S 3/06708 Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering optical fibres as passive waveguides G02B6/02
• CPC Class Codes: H01S 3/06716 Fibre compositions per se C03C13/04or doping with active elements lasing materials in general H01S3/14
• 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 3/06754 Fibre amplifiers H01S3/06708 takes precedence
• CPC Class Codes: H01S 3/06758 Tandem amplifiers
• CPC Class Codes: H01S 3/08013 Resonator comprising a fibre, e.g. for modifying dispersion or repetition rate the active medium being a fibre H01S3/067
• CPC Class Codes: H01S 3/094003 the pumped medium being a fibre
• CPC Class Codes: H01S 3/094076 Pulsed or modulated pumping H01S3/1024 takes precedence
• CPC Class Codes: H01S 3/0941 of a laser diode
• CPC Class Codes: H01S 3/10046 Pulse repetition rate control H01S3/11 takes precedence
• CPC Class Codes: H01S 3/1106 Mode locking
• CPC Class Codes: H01S 3/115 using intracavity electro-optic devices
• CPC Class Codes: H01S 3/1608 erbium
• CPC Class Codes: H01S 3/1618 ytterbium
• CPC Class Codes: H01S 3/2308 Amplifier arrangements, e.g. MOPA
• CPC Class Codes: H01S 3/2375 : Hybrid lasers H01S3/07 takes precedence
• CPC Class Codes: H01S 5/0057 : for temporal shaping, e.g. pulse compression, frequency chirping
• CPC Class Codes: H01S 5/0085 : for modulating the output, i.e. the laser beam is modulated outside the laser cavity
• CPC Class Codes: H01S 5/06216 : Pulse modulation or generation
• CPC Class Codes: H01S 5/12 : the resonator having a periodic structure, e.g. in distributed feedback [DFB] lasers comprising a photonic bandgap structure H01S5/11; surface-emitting lasers H01S5/18
• CPC Class Codes: H04B 10/508 : Pulse generation, e.g. generation of solitons

Abstract

System for converting relatively long pulses from rep-rate variable ultrafast optical sources to shorter, high-energy pulses suitable for sources in high-energy ultrafast lasers. Fibers with positive group velocity dispersion (GVD) and self phase modulation are advantageously employed with the optical sources. These systems take advantage of the need for higher pulse energies at lower repetition rates so that such sources can be cost effective.

Claims

1. A system comprising:

a non-mode-locked source laser generating output pulses, said non-mode-locked source comprising a cw laser diode and a lithium niobate electro-optic modulator disposed at an output of said cw laser diode, wherein said cw laser diode is selectively gated on to generate optical pulses at a repetition rate in the KHz to MHz regime, said modulator receiving said optical pulses and generating modulated output pulses;

a fiber with positive group-velocity dispersion (GVD) and capable of imparting self-phase modulation to an output of said non-mode-locked source, and producing output pulses compressible to pulse widths of about 10 ps or less; and

a pump source for pumping said non-mode locked source, wherein at least a portion of said pump source comprises an electrical pulse generator configured to selectively gate said laser diode.

2. The system according to claim 1, wherein a compressible output pulse comprises a pulse having a pulse width of about 250 ps.

3. The system according to claim 1, further comprising a compressor receiving a compressible output from said fiber and producing a compressed output pulse having a pulse width less than about 10 ps.

4. The system according to claim 1, further comprising a gain switched laser pumped by an output of said compressor.

5. The system according to claim 1, wherein said pump source is gain-switched.

6. The system according to claim 1, wherein said fiber comprises a single-mode fiber.

7. The system according to claim 1, wherein said fiber comprises a coreless end cap, whereby a mode is expanded before a surface of said fiber.

8. The system of claim 1, wherein said non-mode-locked source comprises a microchip laser.

9. The system of claim 1, further comprising a conversion crystal disposed downstream from said fiber for varying the wavelength of an output of said system.

10. The system according to claim 9, wherein said system having said conversion crystal is configured to operate in the UV spectrum.

11. The system according to claimed in claim 1, wherein said fiber is a single mode fiber having a length of approximately 2 meters for a compression ratio of approximately 50.

12. The system according to claim 1, wherein said repetition rate is in the range from about 10 MHz to 100 MHz.

13. The system according to claim 1, wherein said repetition rate is in the range from about 1 KHz to 1 MHz.

14. The system according to claim 1, wherein a wavelength of said CW laser diode is about 1 μ

m or about 1.55 μ

m.

15. The system according to claim 1, further comprising a fiber amplifier disposed downstream from said non-mode-locked source laser.

16. The system according to claim 1, wherein an extinction ratio of said modulator is in the range from about 20-30 dB.

17. The system according to claim 1, wherein a cw power component of the average optical power is insubstantial as a result of said selectively gating of said laser diode.

18. The system according to claim 1, wherein said fiber comprises a multimode fiber.

19. The system according to claim 1, wherein said multimode fiber is configured to propagate a single mode beam.

20. The system according to claim 1, wherein said fiber comprises a holey fiber.

21. The system according to claim 1, wherein said fiber comprises a multi-mode, Yb gain fiber configured as a Yb fiber amplifier.