Femscan -The development of the image dissector to a tube with femtosecond time resolution

ABSTRACT The Image Dissector was one of the firsts all electronic TV tubes and was described by Farnsworth in 1934. (Ref 1). Fifty years later, in 1983, more modern image dissectors were used to measure the electron bunch lengths in synchrotrons. The advent of modern computers and high-speed electronics enables these rather elderly tubes to be used in exciting new applications. This paper described how we have adapted the image dissector to enable the development of low cost instruments with exceptional bandwidth, sensitivity and sampling rate for optical signals

Time-resolved photo-induced nonlinear magneto-optical Kerr effect for the study of spin dynamics at a GaAs(001) surface

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Time-resolved photo-induced nonlinear magneto-optical Kerr effect for the study of surface spin dynamics

International audienceWe introduce time-resolved photo-induced nonlinear magneto-optical Kerr-effect measurements as a tool for studying spin dynamics on the femtosecond time-scale at a GaAs surface. Circularly polarized pump pulses induce a spin polarization in the sample, i.e., a transient magnetizationthat can be followed by magnetically-induced second harmonic generation from delayed probe pulses. We also show that measuring the sum frequency generation due to the coherent interaction of pump and probe pulses can lead to such temporal information as well. Initial results show thata rapid spin relaxation occurs in a time shorter than the pulse duration of our experiment i.e. less than 50 fs

Spin dynamics in GaAs studied with time-resolved photo-induced nonlinear magneto-optics

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Variable Optical Attenuator based on thermally tuned Mach-Zehnder Interferometer within a twin core fiber

International audienceA variable optical attenuator (VOA) based on a tunable Mach-Zehnder interferometer has been produced based on a twin core fiber design. Two achromatic 3 dB-couplers have been manufactured utilizing the fused-stretched technique between both cores of the fiber, in order to obtain a Mach-Zehnder interferometer. A metallic thin layer deposit on one arm of the interferometer allows thermal tuning of the Mach-Zehnder interferometer, which obtains the desired attenuation at the component output. We obtained a −0.5 to −24 dB attenuation-range VOA with an achromatic response from 1535 to 1560 nm