Pulsed lasers based on spatiotemporal mode-locking

Patent metadata

Field	Value
Publication number	US-10965092-B2
Application number	US-201816237342-A
Country	US
Kind code	B2
Filing date	Dec 31, 2018
Priority date	Dec 29, 2017
Publication date	Mar 30, 2021
Grant date	Mar 30, 2021

Abstract

The technology disclosed in this patent document allows mode locking of both selected longitudinal and transverse modes to produce laser pulses. The laser light produced based on such mode locking exhibits a 3-dimensional mode profile based on the locked longitudinal and transverse modes.

First claim

What is claimed is what is described or illustrated, including:

1. A mode-locked laser that produces laser pulses based on mode locking of both selected longitudinal and transverse modes, comprising:
an optical resonator structured to support longitudinal optical modes and transverse optical modes and to provide optical feedback for light to circulate in the optical resonator;
an optical gain medium in the optical resonator to produce optical gain for light at a wavelength within a gain spectral range covering different laser wavelengths;
an optical attenuation device located in the optical resonator and structured to attenuate light in the longitudinal and transverse optical modes and structured to exhibit a saturation in optical attenuation as an optical intensity increases to select light in certain longitudinal and transverse optical modes with a sufficiently high optical intensity to continue circulating in the optical resonator and being further amplified while suppressing light in other optical modes by optical attenuation;
an optical spectral filter located in the optical resonator to select light in certain longitudinal optical modes within a bandpass spectral range to transmit and to circulate in the optical resonator while filtering out light in other longitudinal optical modes; and
an optical spatial filter located in the optical resonator to select certain transverse optical modes to transmit and to circulate in the optical resonator while spatially blocking other transverse optical modes from being present in the optical resonator,
wherein the optical resonator, optical gain medium, the optical attenuation device, the optical spectral filter and the optical spatial filter are structured to collectively cause amounts of dispersions in selected longitudinal optical modes and selected transverse optical modes at selected laser wavelengths within the gain spectral range of the optical gain medium to be comparable and to cause the selected longitudinal optical modes and selected transverse optical modes to be locked in phase relative to one another to produce laser pulses.

2. The mode-locked laser as in claim 1 , wherein:
the optical gain medium includes a doped fiber section to produce the optical gain under optical pump by pump light at a pump wavelength.

3. The mode-locked laser as in claim 1 , wherein:
the optical gain medium includes a doped crystal material to produce the optical gain under optical pump by pump light at a pump wavelength.

4. The mode-locked laser as in claim 1 , wherein:
the optical gain medium includes a semiconductor material to produce the optical gain under optical pump by pump light at a pump wavelength.

5. The mode-locked laser as in claim 1 , wherein:
the optical gain medium includes a semiconductor optical amplifier to produce the optical gain when an electrical voltage or current is applied.

6. The mode-locked laser as in claim 1 , wherein:
the optical resonator includes a Fabry-Perot resonator that includes two end reflectors to bounce light therebetween.

7. The mode-locked laser as in claim 6 , wherein:
one of the two end reflectors includes a semiconductor saturable absorber device and an optical reflector.

8. The mode-locked laser as in claim 1 , wherein:
the optical resonator includes an optical ring resonator having a closed optical loop to circulate light within the optical ring resonator.

9. The mode-locked laser as in claim 8 , wherein:
the optical ring resonator includes one or more fiber sections to guide the light while circulating in the optical ring resonator.

10. The mode-locked laser as in claim 8 , wherein:
the optical ring resonator includes one or more waveguide sections formed on a substrate to guide the light.

11. The mode-locked laser as in claim 8 , wherein:
the optical ring resonator includes optical reflectors arranged at different locations as part of the closed optical loop to guide the light.

12. The mode-locked laser as in claim 1 , wherein:
the optical attenuation device includes an optical saturable absorber.

13. The mode-locked laser as in claim 1 , wherein:
the optical attenuation device includes an optical assembly of optical wave plates and a polarization beam splitter to produce an effective saturable absorption based on nonlinear polarization rotation.

14. The mode-locked laser as in claim 1 , wherein:
the optical attenuation device includes an optical modulator that produces a periodic modulation on light.

15. The mode-locked laser as in claim 1 , wherein:
the spatial filter is structured to allow transmission of light in different transverse modes of the optical resonator to continue circulating.

16. The mode-locked laser as in claim 1 , wherein:
the optical resonator includes only optical components exhibiting normal group velocity dispersion.

17. The mode-locked laser as in claim 1 , wherein:
the optical resonator includes optical components exhibiting normal group velocity dispersion and anomalous dispersion.

18. A method for operating a mode-locked laser to generate laser pulses based on mode locking of both selected longitudinal and transverse modes, comprising:
providing optically saturable absorption of laser light generated by the mode-locked laser in longitudinal and transverse optical modes exhibit a saturation in optical attenuation as an optical intensity increases to select light in certain longitudinal and transverse optical modes with a sufficiently high optical intensity to continue circulating in the mode-locked laser and being further amplified while suppressing light in other optical modes by optical attenuation;
filtering spectral components in the laser light in certain longitudinal optical modes within a bandpass spectral range to circulate in the mode-locked laser while filtering out light in other longitudinal optical modes;
spatially selecting certain transverse optical modes to circulate in the mode-locked laser while spatially blocking other transverse optical modes; and
structuring the mode-locked laser to cause amounts of dispersions in selected longitudinal optical modes and selected transverse optical modes at selected laser wavelengths within the gain spectral range of the mode-locked laser to be comparable and to cause the selected longitudinal optical modes and selected transverse optical modes to be locked in phase relative to one another to produce laser pulses.

19. The method as in claim 18 , further comprising:
providing a passive optical material segment inside the mode-locked laser to improve a beam quality of the laser pulses.

20. The method as in claim 18 , wherein:
filtering spectral components in the laser light includes using two optical bandpass spectral filters designed to have filter center wavelengths to be, respectively, longer and shorter than a peak wavelength of a gain spectrum of the mode-locked laser for shaping the laser pulses.

Assignees

• Univ Cornell

Inventors

• Wright Logan
• Wise Frank

Classifications

• H01S3/06712

  Polarising fibre; Polariser · CPC title

• H01S3/1112

  Passive mode locking · CPC title

• H01S3/0805

  by apertures, e.g. pin-holes or knife-edges · CPC title

• H01S3/1625

  titanium · CPC title

• H01S3/0804

  Transverse or lateral modes · CPC title