Tunable mid-ir fiber laser for non-linear imaging applications

Abstract

A microscopy system, including: a mode-locked fiber laser configured to output a pulse having a center wavelength; a nonlinear waveguide configured to shift the wavelength of the pulse from the mode-locked fiber laser; a fiber amplifier configured to amplify the output from the first nonlinear waveguide; a second-harmonic generator configured to generate femtosecond pulses at twice the optical frequency from the output of the fiber amplifier; and an imaging system.

What is claimed is: 
     
         1 . A two-photon microscopy system, comprising:
 a mode-locked fiber laser configured to output a pulse having a center wavelength;   a nonlinear waveguide configured to shift the wavelength of the pulse from the mode-locked fiber laser;   a fiber amplifier configured to amplify the output from the first nonlinear waveguide;   a second-harmonic generator configured to generate femtosecond pulses at twice the optical frequency from the output of the fiber amplifier; and   a microscopy imaging system.   
     
     
         2 . The system of  claim 1 , wherein the mode-locked fiber laser outputs pulse that supports a transform-limited pulse width shorter than 1 ps and has a center wavelength between 1500 nm and 1650 nm. 
     
     
         3 . 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. 
     
     
         4 . The system of  claim 1 , wherein the first fiber amplifier operates in the wavelength region between 1700 nm and 2800 nm. 
     
     
         5 . 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. 
     
     
         6 . 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. 
     
     
         7 . The system of  claim 1 , further comprising a first dispersive element configured to create a desired amount of chirp on the pulse entering the first fiber amplifier. 
     
     
         8 . 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. 
     
     
         9 . The system of  claim 1 , further comprising a second dispersive element configured to adjust the amount of chirp on the pulse entering the second-harmonic generator. 
     
     
         10 . The system of  claim 1 , further comprising a third polarization controller configured to adjust the polarization state of the pulses entering the second-harmonic generator. 
     
     
         11 . A microscopy system comprising a mode-locked fiber laser, a splitter after the mode-locked fiber laser for splitting the output of the fiber laser into a first path and a second path, the first path further comprising:
 a first nonlinear waveguide;   a first fiber amplifier;   a first second-harmonic generator nonlinear medium;   
       and the second path comprising:
 a second second-harmonic generator nonlinear medium; and 
 the system further comprising a microscope that receives one or two outputs from the first path or the second path. 
 
     
     
         12 . The system of  claim 11  including a second fiber amplifier before the first nonlinear waveguide. 
     
     
         13 . The system of  claim 12 . Where the splitter is placed after the second fiber amplifier and before the first nonlinear waveguide. 
     
     
         14 . The system of  claim 11 , further comprising a variable delay line on the first path or on the second path. 
     
     
         15 . The system of  claim 11 , further comprising a third fiber amplifier on the second path. 
     
     
         16 . A method for operating a multi-photon microscopy system that comprises 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 fiber amplifier with at least one stage configured to amplify the output from the first nonlinear waveguide; and a nonlinear medium configured to frequency-double the output from the first fiber amplifier, the method comprising:
 receiving a feedback from, the output of the first nonlinear waveguide, the output of the first fiber amplifier or the image generated by the microscope; and   adjusting peak power, energy, wavelength or polarization of the pulse entering the nonlinear medium.   
     
     
         17 . A three-photon microscopy system, comprising:
 a mode-locked fiber laser configured to output a pulse having a center wavelength;   a nonlinear waveguide configured to shift the wavelength of the pulse from the mode-locked fiber laser;   a fiber amplifier configured to amplify the output from the first nonlinear waveguide; and   a microscopy imaging system.