Device and method for performing overall frequency stabilization of femtosecond laser optical comb by using optical modes directly extracted from optical comb

Patent metadata

Field	Value
Publication number	US-10141713-B2
Application number	US-201515744921-A
Country	US
Kind code	B2
Filing date	Aug 19, 2015
Priority date	Jul 15, 2015
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

The present invention relates to a device and a method for performing overall frequency stabilization of a femtosecond laser optical comb by using optical modes directly extracted from the optical comb, and more particularly, to a device and a method for performing overall frequency stabilization of a femtosecond laser optical comb by using optical modes directly extracted from the optical comb capable of stabilizing an overall range of frequencies of the femtosecond laser optical comb by using optical modes directly extracted from the optical comb and generating a cw laser and pulse having an excellent frequency stability and linewidth from the stabilized optical comb.

First claim

The invention claimed is:

1. A device for performing overall frequency stabilization of a femtosecond laser optical comb by using optical modes directly extracted from the optical comb, comprising:
a femtosecond laser light source including a length adjusting element and one of a pumping laser and an acousto-optic modulator and outputting the femtosecond laser optical comb;
an optical mode extracting unit extracting a first optical mode and a second optical mode having different frequencies from the femtosecond laser optical comb;
an injection locking unit injecting the first optical mode to a first slave laser to generate a first cw light and injecting the second optical mode to a second slave laser to generate a second cw light; and
a controlling unit including a high-finesse cavity, generating a first optical comb control signal based on the first cw light and a resonance frequency of the high-finesse cavity to control the length adjusting element, and generating a second optical comb control signal based on the second cw light and a resonance frequency of the high-finesse cavity to control the pumping laser or the acousto-optic modulator included in the femtosecond laser light source.

2. The device for performing overall frequency stabilization of a femtosecond laser optical comb by using optical modes directly extracted from the optical comb of claim 1 , wherein the controlling unit includes:
a modulating unit allowing the first cw light to be incident to a first modulator to generate a first modulated light in which a phase or a frequency of the first cw light is modulated and allowing the second cw light to be incident to a second modulator to generate a second modulated light in which a phase or a frequency of the second cw light is modulated;
a standard unit including the high-finesse cavity and allowing the first modulated light and the second modulated light to be incident to the high-finesse cavity and be then reflected from or transmitted through the high-finesse cavity to generate a first standard light and a second standard light;
a first optical comb controlling unit comparing the first standard light frequency and a driving signal frequency of the first modulator with each other to generate the first optical comb control signal; and
a second optical comb controlling unit comparing the second standard light frequency and a driving signal frequency of the second modulator with each other to generate the second optical comb control signal,
the first optical comb control signal adjusts the length adjusting element, and
the second optical comb control signal adjusts the pumping laser or the acousto-optic modulator included in the femtosecond laser light source.

3. The device for performing overall frequency stabilization of a femtosecond laser optical comb by using optical modes directly extracted from the optical comb of claim 2 , wherein the standard unit includes:
a multiplexer integrating optical paths with each other;
the high-finesse cavity having certain resonance frequencies; and
a demultiplexer splitting the optical paths from each other,
the multiplexer integrates the first modulated light and the second modulated light with each other to generate an overlapped light,
the high-finesse cavity reflects or transmits the overlapped light therefrom or therethrough to generate a standard light based on the resonance frequencies and
the demultiplexer splits the standard light to generate the first standard light and the second standard light.

4. The device for performing overall frequency stabilization of a femtosecond laser optical comb by using optical modes directly extracted from the optical comb of claim 2 , wherein the controlling unit includes:
the first optical comb controlling unit including a photodetector, obtaining a first standard signal from the first standard light by using the photodetector, and comparing the first standard signal frequency with the driving signal frequency of the first modulator to generate the first optical comb control signal; and
the second optical comb controlling unit including a photodetector, obtaining a second standard signal from the second standard light by using the photodetector, and comparing the second standard signal frequency with the driving signal frequency of the second modulator to generate the second optical comb control signal.

5. The device for performing overall frequency stabilization of a femtosecond laser optical comb by using optical modes directly extracted from the optical comb of claim 1 , wherein the mode extracting unit includes one of a Bragg grating, a virtually imaged phased array (VIPA), an acousto-optic tunable filter, an interference filter, and a tunable Fabry-Perot interferometer.

6. The device for performing overall frequency stabilization of a femtosecond laser optical comb by using optical modes directly extracted from the optical comb of claim 1 , wherein the length adjusting element includes one of a piezoelectric actuator, a modulator, and a servomotor, and adjust a length of the femtosecond laser light source on the basis of the first optical comb control signal.

7. The device for performing overall frequency stabilization of a femtosecond laser optical comb by using optical modes directly extracted from the optical comb of claim 1 , wherein the pumping laser adjusts an output power of the pumping laser on the basis of the second optical comb control signal to adjust an optical path length.

8. The device for performing overall frequency stabilization of a femtosecond laser optical comb by using optical modes directly extracted from the optical comb of claim 1 , wherein the acousto-optic modulator driving signal frequency may be adjusted on the basis of the second optical comb control signal to adjust a phase of the femtosecond laser optical comb output from the femtosecond laser light source.

9. The device for performing overall frequency stabilization of a femtosecond laser optical comb by using optical modes directly extracted from the optical comb of claim 1 , further comprising an application unit receiving the femtosecond laser optical comb input from the femtosecond laser light source and outputting a cw light and a pulse, wherein the application unit includes:
an optical comb adjusting unit distributing the power of the femtosecond laser optical comb using an optical coupler, broadening the spectrum of the distributed femtosecond laser optical comb using a highly-nonlinear fiber, and/or amplifying the power output of the femtosecond laser optical comb of which the spectrum is broadened by using a fiber amplifier;
and
a cw light generating unit extracting and providing a cw light from the femtosecond laser optical comb output from the optical comb adjusting unit.

10. The device for performing overall frequency stabilization of a femtosecond laser optical comb by using optical modes directly extracted from the optical comb of claim 9 , wherein the fiber amplifier is one of an erbium fiber amplifier, an ytterbium fiber amplifier, and a thulium fiber amplifier.

11. The device for performing overall frequency stabilization of a femtosecond laser optical comb by using optical modes directly extracted from the optical comb of claim 9 , wherein the application unit further includes a pulse generating unit outputting the femtosecond laser optical comb output by the optical comb adjusting unit as it is.

12. The device for performing overall frequency stabilization of a femtosecond laser optical comb by using optical modes directly extracted from the optical comb of claim 1 , wherein the first optical comb control signal is one of a signal obtained by reflecting or trans

Assignees

• Korea Advanced Inst Sci & Tech

Inventors

• Kim Seung-Woo
• Kim Young-Jin
• Chun Byung Jae
• Jang Heesuk
• Kang Hyun Jay

Classifications

• H01S3/1307

  Stabilisation of the phase · CPC title

• H01S3/1396

  by using two modes present, e.g. Zeeman splitting (H01S3/1398 takes precedence) · CPC title

• H01S3/10092 Primary

  Coherent seed, e.g. injection locking · CPC title

• H01S3/2383

  Parallel arrangements · CPC title

• H01S3/139

  by controlling the mutual position or the reflecting properties of the reflectors of the cavity {, e.g. by controlling the cavity length} · CPC title