John Sweetser

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Ultrashort-pulse lasers are now commonly used for multiphoton microscopy, and optimizing the performance of such systems requires careful characterization of the pulses at the tight focus of the microscope objective. We solve this problem by use of a collinear geometry in frequency-resolved optical gating that uses type II second-harmonic generation and(More)
We show that frequency-resolved optical gating combined with spectral interferometry yields an extremely sensitive and general method for temporal characterization of nearly arbitrarily weak ultrashort pulses even when the reference pulses is not transform limited. We experimentally demonstrate measurement of the full time-dependent intensity and phase of a(More)
A continuously pumped Nd:YLF regenerative amplifier has been developed that can amplify 40-psec pulses at a repetition rate of greater than 10 kHz, with an average power in excess of 5 W. Pulse energies are as high as 2.0 mJ at 3 kHz and 640 microJ at 10.5 kHz. The limitation on the amplifier repetition rate that is associated with piezoelectric ringing in(More)
We introduce a transient-grating beam geometry for frequency-resolved optical-gating measurements of ultrashort laser pulses and show that it offers significant advantages over currently used geometries. Background free and phase matched over a long interaction length, it is the most sensitive third-order pulse-measurement geometry. In addition, for pulses(More)
We demonstrate a new all-fiber technique for coherent spectral encoding and decoding based on temporal-spectral dispersion and recombination using suitably chirped fiber Bragg gratings. The application potential to optical-code division multiple access telecommunication is discussed.
We describe a system designed for simple and intuitive interaction with a large screen from a distance. The approach is based on an optical pointing and tracking system which has the important property that the tracking is absolute in nature. This provides several advantages over traditional methods used for input devices and remote controls, especially(More)
We show that cascaded second-order nonlinear-optical processes can occur in a convenient polarization-gate beam geometry. Our arrangement uses type II phase matching, and both individual second-order processes (upconversion and downconversion) are simultaneously phase matched. This geometry can be applied to efficient ultrafast optical switching. With a(More)
Ultrashort-laser-pulse retrieval in frequency-resolved optical gating has previously required an iterative algorithm. Here, however, we show that a computational neural network can directly and rapidly recover the intensity and phase of a pulse.
We propose and demonstrate a new method for single-shot multiplex absorption spectroscopy that permits enhanced sensitivity in the simultaneous measurement of multiple spectral lines in rapidly changing gas-phase media, such as turbulent flames. It uses an ultrashort laser pulse that propagates through the absorbing medium, for which the relevant absorption(More)
We demonstrate reliable operation of a stable synchronously pumped dye amplifier for femtosecond pulses from a passively mode-locked dye laser. Conversion efficiencies of 8% are obtained with output powers of 40 mW and 50-fs pulse widths at repetition rates of up to 10 kHz with pulse energy stability of 3% rms. Synchronization is achieved by driving the(More)
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