Broadband generation of mid ir, coherent continua with optical fibers

A coherent supercontinuum source comprising;

• a fiber-based laser source generating short optical pulses, said fiber-based source generating an output at a central wavelength >1700 nm, said short optical pulses comprising a pulse width <10 ps;
• a nonlinear waveguide for self-frequency shifting the output of said fiber-based source to frequency shifted output wavelengths >2200 nm;
• and
• a highly nonlinear material receiving pulses having said frequency shifted output wavelengths and generating said coherent supercontinuum therewith.

A method for coherent detection comprising:

• providing a short pulse source with a central emission wavelength >1700 nm;
• generating a coherent supercontinuum in a waveguiding material;
• inducing coherent signal emission by irradiating a sample with an output of said short pulse source, said signal emission covering a signal emission spectral region;
• selecting a spectral region within said coherent supercontinuum that corresponds with said signal emission spectral region;
• interfering two spectrally overlapping signals from said signal emission spectral region and from the corresponding region from said supercontinuum on a detector;
• and
• amplifying the detected signal from said signal emission.

A method for lock-in detection comprising:

• providing a short pulse source with a central emission wavelength >1700 nm;
• generating a supercontinuum in a waveguiding material;
• modifying the spectrum of said supercontinuum by inserting a sample into the beam path of said supercontinuum, and irradiating the sample with a portion of said supercontinuum at a modulation frequency;
• and
• detecting modification of the spectrum at said modulation frequency.

A method for determining a characteristic of a sample, the method comprising:

• providing a short pulse source with a central emission wavelength >1700 nm;
• generating a low noise supercontinuum in a waveguiding material;
• irradiating a sample with at least part of said supercontinuum;
• detecting a response to said irradiating step produced by said sample;
• and
• determining a characteristic of said sample based upon said response.

A method for determining a characteristic of a sample using multi-heterodyne detection, the method comprising:

• providing at least one short pulse source with a central emission wavelength >1700 nm;
• generating two coherent supercontinuum spectra, wherein said two supercontinuum spectra comprise individual frequency lines with a certain frequency spacing, said frequency spacing being different for both supercontinuum spectra;
• irradiating a sample with at least a portion of said two supercontinuum spectra;
• detecting a response to said irradiating step produced by said sample;
• and
• determining a characteristic of said sample based upon said response.

A method for spectral detection comprising:

• providing a short pulse source with a central emission wavelength >1700 nm;
• generating a supercontinuum in a waveguiding material;
• modifying the spectrum of said supercontinuum by inserting a sample into the beam path of said supercontinuum;
• irradiating the sample with a portion of said supercontinuum;
• and
• detecting modification of the spectrum.