Ultra-short pulse mid-ir mode-locked laser

Patent metadata

Field	Value
Publication number	US-2016294149-A1
Application number	US-201615085327-A
Country	US
Kind code	A1
Filing date	Mar 30, 2016
Priority date	Sep 30, 2013
Publication date	Oct 6, 2016
Grant date	—

Abstract

A short-pulse mode-locked laser is configured with at least two reflective elements defining a resonant cavity therebetween, a laser gain element (“GE”) placed inside the resonant cavity at normal incidence and selected from transition metal doped II-VI materials; and an optical pump emitting pulsed output to synchronously or quasi-synchronously pump the GE at a pulse repetition rate frequency f pump , the pump being configured so that the f pump substantially matches an inversed round trip time in the resonant cavity f laser :f pump ≈f laser =c/2L, where c is the speed of light, L is the length of the resonant cavity. The synchronous or quasi-synchronous pumping triggers and sustains a short-pulse emission of the laser with picosecond or femtosecond pulse durations.

First claim

1 . (canceled)

2 . A sub-nanosecond mode-locked laser comprising:
at least two reflective elements defining a resonant cavity therebetween; a laser gain element (“GE”) placed inside the resonant cavity, the GE being selected from transition metal doped II-VI materials; and an optical pump emitting a pulsed output to synchronously pump the GE at a pulse repetition rate frequency f pump , the pump being configured so that the f pump substantially matches an inversed round trip time in the resonant cavity f laser :f pump ≈f laser =c/2L, where c is the speed of light, L is the length of the resonant cavity, wherein the synchronous pumping triggers and sustains a short-pulse emission of the laser with picosecond or femtosecond pulse durations.

3 . (canceled)

4 . The laser of claim 2 , wherein the optical pump is configured so that f pump is selected to be within ±10% of the f lase .

5 . The laser of claim 2 , wherein optical pump is configured to trigger and sustain a Kerr Lens mode (“KLM”).

6 . The laser of claim 2 , wherein the GE element includes
transition metals selected from Chromium (“Cr”), Iron (“Fe”) and Cobalt (“Co”) and, TM:II-VI having a single-crystal form or polycrystalline forms and including Chromium doped zinc Selenide (“Cr:ZnSe”), Chromium doped Zinc Sulfide (“Cr:ZnS”), Cr doped Cadmium Selenide (Cr:CdSe), Chromium doped Cadmium Sulfide (Cr:CdS), iron doped Zinc Selenide (Fe:ZnSe), Iron doped Zinc Sulfide (Fe:ZnS), Iron doped Cadmium Selenide (Fe:CdSe), Iron doped Cadmium Sulfide (Fe:CdS), Iron doped Cadmium Tellurium (Fe:CdTe), ternary or quaternary iron doped II-VI GE.

7 - 8 . (canceled)

9 . The laser of claim 2 , wherein the pump is configured as a laser selected from bulk or fiber lasers operative to output pulses in a picosecond-femtosecond duration range.

10 . The laser of claim 2 further comprising at least one dispersion compensation element placed within the resonant cavity and configured to provide a soliton mode-locking regime, the dispersion element including a plane parallel plate (YAG, fused silica sapphire) or a plurality of dispersion compensation prisms or a plurality of dispersive mirrors, wherein the dispersion mirrors each are configured with a multilayer coating selected to provide a desired reflectivity band and a selected dependence of a group delay dispersion on a wavelength.

12 . (canceled)

11 . (canceled)

12 . (canceled)

13 . The laser of claim 2 , wherein the GE is configured in a polycrystalline form having a pattern of non-uniform single crystal grains, the pattern and averages size of the single crystal grains being selected to provide for a random quasi-phase-matched three-wave mixing phenomenon selected from the group which consists of second harmonic generation (SHG), sum-frequency generation (SFG), difference frequency generation (DFG) and optical rectification (OR) and a combination of these in the GE, and to selectively maximize the yield of the SHG, SFG, DFG, or OR.

14 . The laser of claim 13 further comprising an IR photodetector located outside the resonant cavity and configured to detect the SHG, wherein the detection of the SHG is an indicator of the KLM across emission spectra of the laser.

15 . The laser of claim 13 further comprising a feedback loop configured to guide a signal corresponding to the detected SHG to dynamically stabilize the KLM regime.

16 . A femtosecond single pass laser amplifier operative to amplify the emission of the mode-locked mid-IR laser of claims 1 - 15 , comprising:
the laser gain element (“GE”) selected from transition metal doped polycrystalline or single-crystal II-VI materials; the optical pump emitting continuous or discontinuous output; and at least one optical element operative to superimpose and focus the pump beam and the mode-locked mid-IR laser beam in the GE, the at least one optical element or system being operative to separate and collimate the laser beams at the output of GE.

17 - 19 . (canceled)

20 . The laser amplifier of claim 16 , wherein the optical pump is configured as a laser selected from semiconductor, bulk or fiber lasers.

21 . The laser amplifier of claim 16 , wherein the optical pump is configured as a pulsed nanosecond, a picosecond or a femtosecond laser.

22 . (canceled)

Assignees

• Ipg Photonics Corp

Inventors

• Vasilyev Sergey
• Mirov Michael
• Gapontsev Valentin

Classifications

• H01S3/0612

  Non-homogeneous structure (H01S3/07 takes precedence) · CPC title

• H01S3/094026 Primary

  for synchronously pumping, e.g. for mode locking · CPC title

• H01S3/1628

  characterised by a semiconducting matrix · CPC title

• H01S3/0014

  Monitoring arrangements not otherwise provided for (photometry G01J1/00, e.g. G01J1/4257; radiation pyrometry G01J5/00; measuring coherence of light G01J9/00; measuring wavelength of light G01J9/00, e.g. G01J9/0246; measuring optical pulses G01J11/00; calorimetrically measuring power of laser beams G01K17/003) · CPC title

• H01S3/0815

  having 3 reflectors, e.g. V-shaped resonators · CPC title