Adjustable mid-infrared super-continuum generator using a tunable femtosecond oscillator

Patent metadata

Field	Value
Publication number	US-9601899-B2
Application number	US-201514589509-A
Country	US
Kind code	B2
Filing date	Jan 5, 2015
Priority date	Jan 7, 2014
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

A super-continuum system including: a fiber laser configured to output a pulse having a center wavelength; a first nonlinear waveguide configured to shift the wavelength of the pulse from the fiber laser; a first fiber amplifier of at least one stage configured to amplify the output from the first nonlinear waveguide; and a second nonlinear waveguide configured to spectrally broaden the output from the first fiber amplifier.

First claim

What is claimed is:

1. A super-continuum system comprising:
a mode-locked fiber laser with an optical bandwidth corresponding to a transform limited pulse duration of less than 1 ps and a pulse repetition rate of more than 1 MHz configured to output a pulse having a center wavelength;
a first nonlinear waveguide configured to shift the wavelength of the pulse from the mode-locked fiber laser;
a first fiber amplifier of at least one stage configured to amplify the output from the first nonlinear waveguide and further configured to output femtosecond pulses by using the interplay between the dispersion and nonlinearity in the first fiber amplifier; and
a second nonlinear waveguide with a zero-dispersion point that is close to the center wavelength of the pulses exiting the first fiber amplifier configured to spectrally broaden the output from the first fiber amplifier by self-phase modulation.

2. The system of claim 1 , wherein the first nonlinear waveguide shifts the output wavelength from the mode-locked fiber laser to a wavelength longer than 1700 nm and shorter than 2800 nm.

3. The system of claim 2 , wherein the first fiber amplifier operates in the wavelength region between 1700 nm and 2800 nm.

4. The system of claim 1 , wherein the second nonlinear waveguide is fabricated from a material with some transparency in the mid-infrared region.

5. The system, of claim 1 , wherein the second nonlinear waveguide has anomalous dispersion at the center wavelength of the pulses exiting the first fiber amplifier.

6. The system of claim 1 , further comprising a second fiber amplifier configured to boost the power from the mode-locked fiber laser and to control the amount of wavelength shift.

7. The system of claim 1 , further comprising a first polarization controller for controlling an amount of wavelength shift through a Raman soliton self-frequency shifting process.

8. The system of claim 1 , further comprising a first dispersive element configured to create a desired amount of chirp on the pulse entering the second fiber amplifier.

9. The system of claim 1 , further comprising a second polarization controller configured to adjust the polarization state of the pulses entering the first fiber amplifier.

10. The system of claim 1 , further comprising a second dispersive element configured to adjust the amount of chirp on the pulse entering the second nonlinear waveguide.

11. The system of claim 1 , further comprising a third polarization controller to adjust the polarization state of the pulses entering the second nonlinear waveguide.

12. The system of claim 1 , further comprising a third nonlinear waveguide placed between the first fiber amplifier and the second nonlinear waveguide to shift the wavelength of the output from the first fiber amplifier.

13. The system of claim 1 , further comprising a splitter after the second fiber amplifier for splitting the output of the mode-locked fiber laser into a first path and a second path, the output on the first path is coupled to the first nonlinear waveguide and the light from the first fiber amplifier is combined with the output of the second path and coupled to the second nonlinear waveguide, in order to seed the second nonlinear waveguide with two different wavelengths.

14. The system of claim 1 , further comprising a splitter after the mode-locked fiber laser for splitting the output of the mode-locked fiber laser into a first path and a second path, the output on the first path is coupled to the first nonlinear waveguide and the light from the first fiber amplifier is combined with the output of the second path and coupled to the second nonlinear waveguide, in order to seed the second nonlinear waveguide with two different wavelengths.

15. The system of claim 14 , further comprising a variable delay line on the first path or on the second path.

16. The system of claim 14 , further comprising a third fiber amplifier on the second path.

17. The system of claim 1 , further comprising a band-pass filter configured to select a spectral band in the output pulse.

18. A method for operating super-continuum system that comprises a mode-locked fiber laser with an optical bandwidth corresponding to a transform limited pulse duration of less than 1 ps and a pulse repetition rate of more than 1 MHz configured to output a pulse having a center wavelength; a first nonlinear waveguide configured to shift the wavelength of the pulse from the mode-locked fiber laser; a first fiber amplifier with at least one stage configured to amplify the output from the first nonlinear waveguide and further configured to output femtosecond pulses by using the interplay between the dispersion and nonlinearity in the first fiber amplifier; and a second nonlinear waveguide with a zero-dispersion point that is close to the center wavelength of the pulses exiting the first fiber amplifier configured to spectrally broaden the output from the first fiber amplifier by self-phase modulation, the method comprising:
receiving a feedback from, via a feedback loop filter, the output of the first fiber amplifier or the output of the second nonlinear waveguide; and
dynamically adjusting peak power, energy, wavelength or polarization of the pulse entering the second nonlinear waveguide based on the feedback.

19. A spectroscopy system, comprising:
a mode-locked fiber laser with an optical bandwidth corresponding to a transform limited pulse duration of less than 1 ps and a pulse repetition rate of more than 1 MHz configured to output a pulse having a center wavelength;
a first nonlinear waveguide configured to shift the wavelength of the pulse from the mode-locked fiber laser;
a first fiber amplifier of at least one stage configured to amplify the output from the first nonlinear waveguide and further configured to output femtosecond pulses by using the interplay between the dispersion and nonlinearity in the first fiber amplifier;
a second nonlinear waveguide with a zero-dispersion point that is close to the center wavelength of the pulses exiting the first fiber amplifier configured to spectrally broaden the output from the first fiber amplifier by self-phase modulation;
a sample processing unit configured to direct the light output from the super-continuum system to pass through or reflect off a sample; and
a spectrometer or interferometer configured to analyze the light that passes through, reflects off or is scattered by the sample.

20. A method for increasing the spectral coverage of a spectroscopy system that comprises: a mode-locked fiber laser with an optical bandwidth corresponding to a transform limited pulse duration of less than 1 ps and a pulse repetition rate of more than 1 MHz configured to output a pulse having a center wavelength; a first nonlinear waveguide configured to shift the wavelength of the pulse from the mode-locked fiber laser; a first fiber amplifier of at least one stage configured to amplify the output from the first nonlinear waveguide and further configured to output femtosecond pulses by using the interplay between the dispersion and nonlinearity in the first fiber amplifier; a second nonlinear waveguide with a zero-dispersion point that is close to the center wavelength of the pulses exiting the first fiber amplifier configured to spectrally broaden the output from the first fiber amplifier by self-phase modulation; a sample processing unit configured to direct the light output from the super-continuum system to pass through or reflect off a sample; and a spectrometer or interferometer config

Assignees

• Thorlabs Inc

Inventors

• Salem Reza
• Fendel Peter
• Cable Alex

Classifications

• G01N2021/3595

  using FTIR · CPC title

• G01N21/45

  using interferometric methods; using Schlieren methods · CPC title

• H01S3/11 Primary

  Mode locking; Q-switching; Other giant-pulse techniques, e.g. cavity dumping · CPC title

• G02B21/0076

  arrangements using fluorescence or luminescence · CPC title

• G01N21/35

  using infrared light (G01N21/39 takes precedence) · CPC title