Dual Self-Diffraction Dispersion-Scan and Its Application to the Simultaneous Measurement of Two Ultrashort Ultraviolet Pulses Produced by a Spatially Inhomogeneous Multiplate Continuum

Summary form only given. In this work we demonstrate the first self-diffraction dispersion-scan (SD d-scan) measurements of a near-UV supercontinuum source produced by multiplate continuum (MPC) [1]. Due to the nature of the spectral broadening, the emerging MPC beam presents spatio-spectral inhomogeneities. Such inhomogeneities can be a hindrance when attempting to characterize a pulse via self-diffraction-based schemes (as normally required when measuring ultraviolet pulses), since ultrashort pulse measurement techniques generally assume and rely on nonlinear effects generated by replicas of the same pulse, which in this case is an invalid assumption. While some techniques are able to provide full spatio-temporal characterization of a pulse, such techniques can be quite complex in nature. When a full spatio-temporal characterization is not deemed necessary, e.g., in the case where only two portions/pulses from the same beam must be known, we can apply a self-diffraction d-scan [2] scheme to simultaneously characterize the two pulses from the measurement of only one d-scan trace (Fig. 1), which we call dual SD d-scan. The two pulses were produced by spatially selecting two portions of a supercontinuum beam produced by MPC of the second-harmonic of a Ti:Sapphire laser amplifier at 400 nm [3]. The pulses then crossed a thin (30 μm) fused silica slide, generating a self-diffraction signal that was measured with a spectrometer as a function of dispersion introduced by a chirped mirror and glass wedges compressor, hence obtaining a dual d-scan trace (Fig. 1, top left). The dual SD d-scan algorithm, which assumes an SD signal produced by two different pulses, revealed two ultraviolet pulses with durations in the 10 fs range (Fig. 1, right).