A dispersion interferometer based on the second-harmonic generation of a carbon dioxide laser in orientation-patterned gallium arsenide has been developed for measuring electron density in plasmas. The interferometer includes two nonlinear optical crystals placed on opposite sides of the plasma. This instrument has been used to measure electron line densities in a pulsed radio-frequency generated argon plasma.
View Article and Find Full Text PDFA nonlinear optical processor that is capable of true real-time conversion of spatial-domain images to ultrafast time-domain optical waveforms is presented. The method is based on four-wave mixing between the optical waves of spectrally decomposed ultrashort pulses and spatially Fourier-transformed quasi-monochromatic images. To achieve efficient wave mixing at a femtosecond rate we utilize a cascaded second-order nonlinearity arrangement in a beta-barium borate crystal with type II phase matching.
View Article and Find Full Text PDFIn response to a comment on our Letter [Opt. Lett. 25, 132 (2000)], we reiterate the distinction between the spectral inversion and the spectral phase conjugation processing techniques.
View Article and Find Full Text PDFTwo different realizations of time-reversal experiments of ultrafast waveforms are carried out in real time by use of four-wave mixing arrangements of spectrally decomposed waves. The first, conventional, method is based on phase conjugation of the waveform's spectrum and achieves time reversal of real amplitude waveforms. The second arrangement of the spectrally decomposed waves spatially inverts the waveform's spectrum with respect to the optical axis of the processor and achieves true time reversal for complex-amplitude ultrafast waveforms.
View Article and Find Full Text PDFWe present an experimental technique capable of single-shot recording of an ultrashort laser pulse sonogram by use of two-photon absorption in a conventional silicon CCD camera. The quadratic spectral phase, introduced into a 100-fs pulse by a grating stretcher, was measured and found to be in good agreement with the analytically calculated value. The nonlinear response of silicon allows sonogram characterization in a wavelength range from 1 to 2 mum .
View Article and Find Full Text PDFWe report on a passively mode-locked all-fiber laser oscillator at 1.5 microm based on heavily doped phosphate-glass active fiber. An active fiber only 20 cm long is sufficient to produce as much as 2.
View Article and Find Full Text PDFWe demonstrate a novel method for spectral analysis of microwave signals that employs time-domain processing in fiber. We use anomalous dispersion in single-mode fiber to perform a Fresnel transform followed by a matched amount of dispersion-compensating fiber to perform an inverse Fresnel transform of an ultrashort pulse. After the Fresnel-transformed waveform is modulated by the microwave signal, the waveform at the output of the dispersion-compensating fiber represents the ultrashort pulse convolved with the microwave spectrum.
View Article and Find Full Text PDFAn experimental technique for single-shot generation of the sonogram of an ultrashort laser pulse is demonstrated. The method is based on the time gating of a spectrally decomposed test signal, transferring its spectral phase into a spatial phase, and the spatial filtering of the signal to produce a sonogram. The technique is evaluated experimentally, producing sonograms for linearly and nonlinearly chirped femtosecond laser pulses.
View Article and Find Full Text PDFWe present an experimental setup capable of performing a single-shot interferometric correlation of femtosecond pulses using two-photon conductivity in a standard silicon CCD camera. The method is demonstrated with 100-fs pulses at 1.4 microm.
View Article and Find Full Text PDFJ Opt Soc Am A Opt Image Sci Vis
February 2001
The operational characteristics of a time-to-space processor based on three-wave mixing for instantaneous imaging of ultrafast waveforms are investigated. We assess the effects of various system parameters on the processor's important attributes: time window of operation and signal conversion efficiency. Both linear and nonlinear operation regimes are considered, with use of a Gaussian pulse profile and a Gaussian spatial mode model.
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