Laser systems and related mehtods

• US 10,069,272 B2
• Filed: 07/14/2017
• Issued: 09/04/2018
• Est. Priority Date: 11/28/2013
• Status: Active Grant

• Current Assignee: Candela Corporation
• Original Assignee: Candela Corporation
• Inventors: Bhawalkar, Jayant D., Shang, Xiaoming, Qiu, Jinze, Jones, Christopher J., Hsia, James
• Primary Examiner(s): Nguyen, Dung
• Application Number:
  US15/649,897
• Publication Number:
  US 20170317465A1
• Time in Patent Office: 417 Days
• CPC Class Codes: H01S 2301/02 ASE (amplified spontaneous emission), noise; Reduction thereof
• CPC Class Codes: H01S 3/0092 Nonlinear frequency conversion, e.g. second harmonic generation [SHG] or sum- or difference-frequency generation outside the laser cavity nonlinear frequency conversion per se G02F1/35
• CPC Class Codes: H01S 3/061 with elliptical or circular cross-section and elongated shape, e.g. rod
• CPC Class Codes: H01S 3/0617 having a varying composition or cross-section in a specific direction
• CPC Class Codes: H01S 3/0625 Coatings on surfaces other than the end-faces
• CPC Class Codes: H01S 3/0627 the resonator being monolithic, e.g. microlaser
• CPC Class Codes: H01S 3/06754 Fibre amplifiers H01S3/06708 takes precedence
• CPC Class Codes: H01S 3/08081 Unstable resonators
• CPC Class Codes: H01S 3/092 of flash lamp H01S3/0937 takes precedence ; flash lamps per se H01J61/80; circuit arrangements for operating flash lamps in general H05B41/30
• CPC Class Codes: H01S 3/094053 Fibre coupled pump, e.g. delivering pump light using a fibre or a fibre bundle
• CPC Class Codes: H01S 3/094061 Shared pump, i.e. pump light of a single pump source is used to pump plural gain media in parallel
• CPC Class Codes: H01S 3/094069 Multi-mode pumping
• CPC Class Codes: H01S 3/10023 by functional association of additional optical elements, e.g. filters, gratings, reflectors
• CPC Class Codes: H01S 3/109 Frequency multiplication, e.g. harmonic generation
• CPC Class Codes: H01S 3/1115 using intracavity saturable absorbers
• CPC Class Codes: H01S 3/113 using intracavity saturable absorbers
• CPC Class Codes: H01S 3/1312 by controlling the optical pumping
• CPC Class Codes: H01S 3/1611 neodymium
• CPC Class Codes: H01S 3/1633 BeAl2O4, i.e. Chrysoberyl
• CPC Class Codes: H01S 3/1643 YAG
• CPC Class Codes: H01S 3/2308 : Amplifier arrangements, e.g. MOPA

Abstract

A MOPA laser system that includes a seed laser configured to output pulsed laser light, an amplifier configured to receive and amplify the pulsed laser light emitted by the seed laser; and a pump laser configured to deliver a pump laser beam to both the seed laser and the amplifier.

Claims

1. A high-energy laser system, comprising:

a seed laser constructed and arranged to output a sub-nanosecond pulsed laser beam;

an amplifier constructed and arranged to receive and amplify a sub-nanosecond pulsed laser light emitted by the seed laser; and

a solid state pump laser constructed and arranged to deliver a pump laser beam to both the seed laser and the amplifier via at least one optical fiber,

wherein to generate sub-nanosecond pulses, a resonator of the seed laser is made short by bonding a saturable absorber to a laser rod, and depositing resonator mirrors directly on to the end surfaces of laser rod and saturable absorber assembly.

2. The laser system of claim 1, wherein in order to prevent occurrence of hot spots in the seed laser output beam, the resonator of the seed laser is an unstable resonator.

3. The laser system of claim 1, further comprising a frequency doubling device configured to receive an output laser beam with wavelength of 1064 nm and double the frequency such as to produce an output laser beam with wavelength of 532 nm.

4. The laser system of claim 1, wherein to minimize amplified spontaneous emission caused by reflections from a barrel surface of a seed laser rod, the seed laser rod diameter is at least three times larger than that of pumped region dimension.

5. The laser system of claim 1, wherein pulses emitted by the pump laser have constant energy, and wherein a variable attenuator is used to adjust a pump beam energy conducted to at least the amplifier.

6. The laser system of claim 1, having a laser beam shaping segment, comprising a reverse Galilean optical system configured to receive and shape to a desired diameter an output laser beam.

7. The laser segment of claim 6, wherein the reverse Galilean optical system includes two lenses.

8. The laser system of claim 1, having a saturable absorber inserted in a path of an output beam and configured to minimize ASE and prevent self-lasing mode of operation.

9. The laser system of claim 8, wherein the saturable absorber is further configured to minimize reflections of output laser beam from a work material.

10. The laser system of claim 1, wherein the amplifier is located within a treatment handpiece.

11. The laser system of claim 1, wherein a frequency doubling device is located within a treatment handpiece.

12. The laser system of claim 1, wherein the beam shaping segment is located within a treatment handpiece.

13. A high-energy laser system, comprising:

a seed laser constructed and arranged to output a sub-nanosecond pulsed laser beam;

an amplifier constructed and arranged to receive and amplify a sub-nanosecond pulsed laser light emitted by the seed laser; and

a solid state pump laser constructed and arranged to deliver a pump laser beam to both the seed laser and the amplifier via at least one optical fiber,

wherein the output of the seed laser is greater than 5 mj and gain of the amplifier is less than 100,

wherein the seed laser is made short by using a saturable absorber diffusion bonded to laser rod and used as a passive Q-switch.

14. A high-energy, sub-nanosecond laser system comprising:

a seed laser constructed and arranged to output a sub-nanosecond pulsed laser beam;

the seed laser comprising a short resonator with a saturable absorber diffusion bonded to a laser rod;

an amplifier constructed and arranged to receive and amplify the pulsed laser beam emitted by the seed laser;

a pump laser constructed and arranged to deliver a pump laser beam to both the seed laser and the amplifier; and

a saturable absorber disposed between the seed laser and the amplifier to prevent self-lasing.

15. The laser system of claim 14, wherein the saturable absorber diffusion bonded to laser rod is used as a passive Q-switch.

16. The laser system of claim 14, wherein to minimize amplified spontaneous emission caused by reflections from a barrel surface of a seed laser rod, the seed laser rod has a diameter at least three times larger than that of pumped region.

17. The laser system of claim 14, wherein pulses emitted by the pump laser have constant energy, and wherein a variable attenuator is used to adjust a pump beam energy conducted to at least the amplifier.