Broadband single-shot interferometric retrieval of spectral phase and amplitude

Knowledge of the phase and amplitude of an optical field is of critical importance in many applications, for example in measuring the carrier envelope phase of an ultrashort pulse. While the intensity spectrum can easily be obtained using a spectrometer, there is no direct method for measuring the phase. Retrieving phase information requires use of an interferometer to compare the signal phase against the phase of a known reference source. To resolve ambiguity in the sign of the phase, the field quadrature can be measured at the output of a polarising beam splitter [1] . Interferometry requires, however, that the reference source is stable and has a spectrum at least as broad as the one under study, which can in some cases be multi-octave in extent. Here we report an experiment in which the reference is provided by a supercontinuum generated in a twisted all-normal dispersion (t-ANDi) fibre.