Methods and system for optically correlating ultrashort optical waveforms
AssigneeMassachusetts Institute of Technology
InventorsAlexi A. Maznev, Timothy F. Crimmins, Keith A. Nelson
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Abstract
The invention features methods and systems for optical correlation of ultrashort optical waveforms, e.g., pulses. The optical waveform passes through a diffractive optic, e.g., a mask or grating, to generate multiple sub-beams corresponding to different diffractive orders. At least two of the sub-beams are then imaged onto the sample to produce a desired crossing pattern. To perform the correlation, the diffracted sub-beams are variably delayed relative to one another prior to overlapping on the sample. The sample generates a signal beam in response to the overlapping sub-beams, the signal beam providing a correlation between the sub-beams for each of the variable delays.
Claims22
A method for autocorrelating an optical waveform comprising:
- passing an input beam containing the optical waveform through a diffractive mask to form at least two sub-beams;
- delaying one of the sub-beams relative to the other sub-beam;
- and
- imaging the two sub-beams onto a non-linear optical crystal to allow the two sub-beams to spatially overlap with one another, the diffractive mask defining the object plane and the non-linear optical crystal defining the image plane, the overlapping sub-beams being delayed relative to one another, and the non-linear optical crystal generating a signal beam in response to the overlapping sub-beams.
An optical autocorrelator for characterizing an an optical waveform, the autocorrelator comprising:
- a diffractive mask which during operation diffracts an input beam carrying the optical waveform into at least two sub-beams;
- an optical delay assembly positioned in the path of a first of the two sub-beams, wherein during operation the optical assembly introduces a variable delay between the two sub-beams;
- a non-linear optical crystal;
- an optical imaging system defining an object plane and an image plane and which during operation images the two sub-beams onto the non-linear optical crystal to allow the two sub-beams to spatially overlap one another, the diffractive mask being positioned in the object plane and the non-linear optical crystal being positioned in the image plane;
- and
- an analyzer which during operation measures an intensity of a signal beam produced by the non-linear optical crystal in response to the two overlapping sub-beams.
Dependencies are inferred from the claim text.