Modular, high energy, widely-tunable ultrafast fiber source

• US 9,819,142 B2
• Filed: 08/05/2013
• Issued: 11/14/2017
• Est. Priority Date: 05/23/2000
• Status: Expired due to Term

• Current Assignee: IMRA America Incorporated (Aisin Corp.)
• Original Assignee: IMRA America Incorporated (Aisin Corp.)
• Inventors: Fermann, Martin E.
• Primary Examiner(s): Rodriguez, Armando
• Application Number:
  US13/958,703
• Publication Number:
  US 20140036939A1
• Time in Patent Office: 1,562 Days
• Field of Search: 372 6, 372 18, 372 25, 372 27, 372102
• 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 3/0675 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 3/094019 Side pumped fibre, whereby pump light is coupled laterally into the fibre via an optical component like a prism, or a grating, or via V-groove coupling
• CPC Class Codes: H01S 3/094042 of a fibre laser
• CPC Class Codes: H01S 3/109 Frequency multiplication, e.g. harmonic generation
• CPC Class Codes: H01S 3/1112 Passive mode locking
• CPC Class Codes: H01S 3/1115 using intracavity saturable absorbers
• CPC Class Codes: H01S 3/1616 thulium
• CPC Class Codes: H01S 3/1618 ytterbium
• CPC Class Codes: H01S 3/302 in an optical fibre

Abstract

A modular, compact and widely tunable laser system for the efficient generation of high peak and high average power ultrashort pulses. Peak power handling capability of fiber amplifiers is expanded by using optimized pulse shapes, as well as dispersively broadened pulses. Dispersive pulse stretching in the presence of self-phase modulation and gain results in the formation of high-power parabolic pulses. To ensure a wide tunability of the whole system, Raman-shifting of the compact sources of ultrashort pulses in conjunction with frequency-conversion in nonlinear optical crystals can be implemented, or an Anti-Stokes fiber in conjunction with fiber amplifiers and Raman-shifters are used. Positive dispersion optical amplifiers are used to improve transmission characteristics. An optical communication system utilizes a Raman amplifier fiber pumped by a train of Raman-shifted, wavelength-tunable pump pulses, to thereby amplify an optical signal which counterpropagates within the Raman amplifier fiber with respect to the pump pulses.

Claims

1. A passively modelocked fiber laser, comprising:

a laser cavity comprising at least one Yb or Nd doped gain fiber; and

a pump diode to pump said laser cavity,

wherein said laser cavity is configured for operation in a positive dispersion regime without negative dispersion cavity components.

2. The passively modelocked fiber laser according to claim 1, further comprising a saturable absorber disposed in said laser cavity to initiate mode locking.

3. The passively modelocked fiber laser according to claim 1, wherein said doped gain fiber is a Yb doped gain fiber configured as polarization maintaining fiber.

4. The passively modelocked fiber laser according to claim 1, wherein said cavity comprises a polarizer to select a polarization state.

5. The passively modelocked fiber laser according to claim 1, wherein said pump diode and said Yb or Nd doped gain fiber are arranged for cladding pumping.

6. The passively modelocked fiber laser according to claim 1, wherein said laser cavity comprises an unchirped fiber Bragg grating, and wherein pulses oscillating in said cavity are positively chirped.

7. The passively modelocked fiber laser of claim 1, wherein said cavity is configured such that an oscillation bandwidth of intracavity pulses is small compared to the gain bandwidth of Yb.

8. The passively modelocked fiber laser of claim 1, wherein said cavity comprises a fiber grating arranged as a cavity end mirror, said fiber grating having a reflection bandwidth smaller than a gain bandwidth of said Yb or Nd doped gain fiber.

9. An optical pulse source, comprising:

a passively modelocked fiber laser according to claim 1, and

a Yb amplifier disposed downstream from said passively modelocked fiber laser and configured to amplify an output of said passively mode locked fiber laser.

10. The optical pulse source according to claim 9, wherein said Yb amplifier is configured to generate parabolic pulses.

11. The optical pulse source according to claim 9, further comprising a saturable absorber disposed in said fiber laser cavity to initiate mode locking.

12. The passively modelocked fiber laser according to claim 1, wherein said passively modelocked fiber laser is configured as a portion of a femtosecond seed source.

13. The passively modelocked fiber laser according to claim 1, wherein said passively modelocked fiber laser generates an ultrashort output pulse having a pulse width in the range from about 0.2 ps to about 1 ps.

14. The optical pulse source according to claim 10, wherein said parabolic pulses are compressible to a pulse width on the order of 100 fs.