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The WIZZLER: A new femtosecond measurement device based on spectral interferometry
Self-referenced Spectral Interferometry is a recently demonstrated femtosecond pulse measurement method [1]. This technique relies on Fourier-Transform Spectral Interferometry (FTSI)[2], i.e. the treatment of the frequency-domain interference pattern between the pulse to measure and a delayed reference pulse with a broader spectrum and a known phase.
Fastlite has taken advantage of Cross Polarized Wave generation (XPW), a third order non linear effect, to generate the reference pulse necessary for the characterization of a femtosecond laser pulse based on FTSI.
The Self Referenced Spectral Interferometry technique consists of three steps. The first step is the creation of an on-axis, orthogonally polarized, time-delayed and low-intensity replica of the input pulse. Experimentally, a thin uniaxial birefringent crystal, such as a calcite plate, cut orthogonally to the optical axis and slightly rotated with respect to the input polarization direction can be used. In the second step, the beam is focused into a thin third order non linear crystal. The main pulse thus generates an orthogonally polarized and temporally filtered pulse (the XPW signal), whereas the pulse replica is linearly transmitted. The beam is then recollimated and a polarizer filters out the residual main pulse. Eventually, a spectrometer records the SRSI spectrum, i.e. the spectral interference pattern between the replica of the input pulse and the XPW signal:
The time delay between the pulse replicas depends on the Calcite plate thickness and a simple super-gaussian filter in the time domain can be used to isolate the two following terms:
From these terms, the spectral amplitudes and spectral phases of both the input and XPW pulses are retrieved analytically.
Click here to download the WIZZLER data sheet and specifications
Click here to see the additional WIZZLER features when coupled to a DAZZLER pulse shaper
[1] T. Oksenhendler, S. Coudreau, N. Forget, V.Crozatier, S.Grabielle, R.Herzog, D.Kaplan and O.Gobert, “Self-referenced spectral interferometry”, App.Phys.B 99, 7-12 (2010).
[2] C.Dorrer, M.Joffre, ” Characterization of the spectral phase of ultrashort light pulses ”, C.R. Acad. Sci. Paris, t.2, Série IV, p.1415-1426, 2001.
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Single shot, single beam