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

• US 7,330,301 B2
• Filed: 05/14/2003
• Issued: 02/12/2008
• 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): Keith; Jack
• Assistant Examiner(s): Bolda; Eric
• Application Number:
  US10/437,057
• Publication Number:
  US 20040240037A1
• Time in Patent Office: 1,735 Days
• Field of Search: 359/333, 385/123
• US Class Current: 359/333
• 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 combination comprising:

a pulse source outputting pulses having a pulse width between 1 picosecond and approximately 10 nanoseconds in duration at a repetition rate in a range of from 1 kHz to less than 10 MHz;

an amplifier directly receiving an unstretched output of said pulse source; and

a fiber with net positive group-velocity dispersion (GVD) and self phase modulation receiving an output of said amplifier and spectrally broadening said pulses.

7. The combination as claimed in claim 1, wherein said source includes a laser diode.

8. The combination as claimed in claim 1, wherein said source is internally modulated.

9. The combination as claimed in claim 1, further comprising means for removing a pedestal from pulses output from said fiber with positive GVD.

10. The combination as claimed in claim 7, wherein a pulse shape output from said diode is sufficiently parabolic for amplification in a parabolic pulse amplifier.

13. The combination as claimed in claim 1, wherein said amplifier is one of a multimode fiber and a holey fiber amplifier.

17. The combination according to claim 1, wherein said seed source comprises a modulated semiconductor laser.

2. A combination comprising:

a pulse source outputting pulses having a pulse width between 1 picosecond and approximately 10 nanoseconds in duration at a variable repetition rate in a range of from 1 kHz to less than 10 MHz; and

a fiber amplifier which includes at least one fiber with net positive group-velocity dispersion (GVD) and self phase modulation receiving an unstretched output of said pulse source and spectrally broadening said pulses.

11. The combination as claimed in claim 2, wherein said fiber is a multimode fiber in single mode operation for self phase modulation, and pulse energy is greater than 500 nJ.

12. The combination as claimed in claim 2, wherein said fiber is a single mode fiber having a length of approximately 2 meters for a compression ratio of approximately 50.

14. The combination as claimed in claim 2, wherein pulse energies are greater than 1 μ

J, said fiber is a multimode fiber, and said pulses are stretched.

3. A combination comprising:

a pulse source outputting pulses having a pulse width between 1 picosecond and approximately 10 nanoseconds in duration at a variable repetition rate in a range of from 1 kHz to less than 10 MHz; and

a fiber amplifier with net positive group-velocity dispersion (GVD) and self phase modulation receiving said pulses directly, as output by said pulse source, said fiber amplifier amplifying and spectrally broadening said pulses.

4. A combination comprising:

a pulse source outputting pulses having a pulse width between 1 picosecond and approximately 10 nanoseconds in duration at a variable repetition rate in a range of from 1 kHz to less than 10 MHz; and

a fiber with net positive group-velocity dispersion (GVD) and self phase modulation receiving an unstretched output of said pulse source and spectrally broadening said pulses,

wherein said fiber is arranged in a double pass configuration.

18. The combination according to claim 4, wherein said semiconductor laser is gain switched.

19. The combination according to claim 4, wherein said semiconductor laser is externally modulated.

5. A system comprising:

a pulse source outputting pulses havina a pulse width between 1 picosecond and approximately 10 nanoseconds in duration at a repetition rate in a range of from 1 kHz to less than 10 MHz, said pulse source comprising a light source; and

a net positive group-velocity dispersion (GVD) fiber receiveng an unstretched output of said light source, and causing spectral generation by self phase modulation in said fiber.

6. A system comprising:

a pulse source outputting pulses, said pulse source comprising a light source;

a net positive group-velocity dispersion (GVD) fiber receiving an unstretched output of said light source, and causing spectral generation by self phase modulation in said fiber; and

an amplifier receiving an output of said positive GVD fiber, said amplifier being a parabolic amplifier.

15. A high power nonlinear fiber amplification system comprising:

a seed source producing pulses with a pulse width shorter than 1 ns and longer than 1 ps, a nonlinear fiber amplifier, said amplifier being configured to spectrally broaden said seed pulses in the presence of positive dispersion, gain, and self-phase modulation, and to generate substantially linearly chirped pulses with a spectral bandwidth up to approximately 50 times larger than a spectral bandwidth of said seed pulses and wherein the chirp is substantially generated during or after the amplification process.

16. A high power nonlinear fiber amplification system according to claim 15, further comprising a pulse compressor following said nonlinear amplifier recompressing the pulses to substantially shorter duration than the seed source pulses.