Fiber-laser pumped crystal-laser

Patent metadata

Field	Value
Publication number	US-9941654-B2
Application number	US-201514842058-A
Country	US
Kind code	B2
Filing date	Sep 1, 2015
Priority date	Sep 1, 2015
Publication date	Apr 10, 2018
Grant date	Apr 10, 2018

Abstract

An apparatus for generating and amplifying laser beams at approximately 1 micrometer wavelength is disclosed. The apparatus includes an ytterbium-doped gain-crystal pumped by an ytterbium fiber-laser. The fiber-laser enables a pump wavelength to be selected that minimizes heating of the gain-crystal. The apparatus can be configured for generating and amplifying ultra-fast pulses, utilizing the gain-bandwidth of ytterbium-doped gain-crystals.

First claim

What is claimed is:

1. Optical apparatus comprising:
a light source for generating a pulsed laser beam, the pulsed laser beam having a signal-wavelength;
an ytterbium-doped gain-crystal having an emission wavelength about equal to the signal-wavelength, said ytterbium-doped gain-crystal for amplifying the pulsed laser beam;
an ytterbium fiber-laser delivering a beam of laser-radiation at a pump-wavelength between 1000 nm and 1032 nm, the pump-wavelength being shorter than the signal-wavelength, the pump-wavelength beam and the signal-wavelength beam arranged to propagate collinearly;
an optical system including at least one focusing element and at least one reflective element, the optical system arranged to receive the collinear pump-wavelength and the signal-wavelength beams, focus the collinear pump-wavelength and signal-wavelength beams at a common location in the gain-crystal, cause the collinear pump-wavelength and the signal-wavelength beams to make a predetermined plurality of focused interactions with the gain-crystal at the common location for amplifying the signal-wavelength beam, and deliver the amplified signal-wavelength beam from the apparatus; and
wherein the amplifier apparatus has a quantum-defect less than about 4.5%, wherein the quantum-defect is defined as being the difference between the pump-wavelength and the signal-wavelength divided by the signal-wavelength.

2. The apparatus of claim 1 , wherein the signal-wavelength beam is delivered from a source thereof through the fiber-laser, and exits the fiber-laser collinear with the pump-wavelength beam.

3. The apparatus of claim 1 , wherein the pump-wavelength beam from the fiber laser and the signal-wavelength beam are combined collinearly by a beam-combiner.

4. The apparatus of claim 3 , wherein the beam-combiner is a polarization-selective beam-combiner.

5. The apparatus of claim 1 , wherein the pump-wavelength beam from the fiber laser and the signal-wavelength beam are arranged to counter-propagate collinearly through the optical system.

6. The apparatus of claim 1 , wherein the pump-wavelength beam after a first complete pass through the optical system is reflected back into the optical system, collinear with the signal-wavelength beam.

7. The apparatus of claim 1 , wherein the common location is inside the gain-crystal and spaced from surfaces of the gain-crystal.

8. The apparatus of claim 1 , wherein the common location is adjacent a first surface of the gain-crystal opposite a second surface of the gain-crystal where the pump-wavelength and the signal-wavelength beams first enter the crystal and wherein the first surface of the gain-crystal includes a coating reflective for the pump-wavelength and the signal-wavelength beams.

9. The apparatus of claim 1 , wherein the ytterbium-doped gain-crystal is a crystal of a material selected from the group of materials consisting of YAG, calcium fluoride, CALGO, and KGW.

10. Optical apparatus comprising:
a light source for generating a pulsed laser beam, the pulsed laser beam having a signal-wavelength;
a ytterbium doped gain-crystal, the gain-crystal having an emission wavelength about equal to the signal-wavelength, the gain-crystal having an absorption wavelength about equal to a pump-wavelength, the signal-wavelength being longer than the pump-wavelength, the gain-crystal having a quantum-defect less than about 4.5%, wherein the quantum-defect is defined as the difference between the pump-wavelength and the signal-wavelength divided by the signal-wavelength, the gain crystal for amplifying the pulsed laser beam;
a pump laser delivering a beam of laser radiation at the pump-wavelength between 1000 nm and 1032 nm, the pump-wavelength beam and the signal-wavelength beam arranged to propagate collinearly; and
an optical system including at least one focusing element and at least one reflective element, the optical system arranged to receive the collinear pump-wavelength and signal-wavelength beams, focus the collinear pump-wavelength and signal-wavelength beams to a common location in the gain-crystal, and cause the collinear pump-wavelength and signal-wavelength beams to make a predetermined plurality of focused interactions within the gain-crystal, for energizing the gain-crystal and amplifying the focused signal-beam, the optical system arranged to deliver the amplified signal-wavelength beam from the apparatus.

11. The apparatus of claim 10 , wherein the host material is YAG.

Assignees

• Coherent Inc

Inventors

• Starodoumov Andrei
• Simanovski Dmitri

Classifications

• H01S3/094084

  with pump light recycling, i.e. with reinjection of the unused pump light, e.g. by reflectors or circulators · CPC title

• H01S3/094038

  End pumping · CPC title

• H01S3/06716 Primary

  Fibre compositions (per se C03C13/04)or doping with active elements (lasing materials in general H01S3/14) · CPC title

• H01S3/1643

  YAG · CPC title

• H01S3/0621

  Coatings on the end-faces, e.g. input/output surfaces of the laser light · CPC title