Measurement Systems for duration of ultra-short pulse laser with degenerate four waves mixing

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Measurement system for duration of ultra-short pulse laser with degenerate four-wave mixing process has been investigated. Photorefractive quantum well structure was grown by molecular beam epitaxy. After some mechanical and chemical processing, optical devices were fabricated by ourselves. In order to characterize the diffraction properties of these optical devices of quantum well structure, we perform degenerate four-wave mixing experiment. The grating writing laser is split into two beams by a cube beam splitter. These two beams interfere in the quantum well optical device without foucusing. The diffracted beam from the grating structure in quantum well is detected using a spectrometer to characterize the diffraction ability of the optical device. The desirable property can be observed from our optical devices. In the future, pulse duration measurement will be carried out by using our optical devices. In addition, the duration of ultra-short laser pulse was measured by collinear second harmonic generation geometry by using nonlinear BaB2O4 crystal. Good results were obtained. Nonlinear process with oxide optical crystal is easy to use. However, it needs to use high power laser beams.