A new transform-limited criterion measured by an intensity autocorrelator and an optical spectrum analyzer

Although intensity autocorrelation is a widely used technique for measuring ultrashort pulses, there is ambiguity in getting the pulse profiles from autocorrelator traces, and often a Gaussian or soliton profile is assumed for We have tested the new transform-limited criterion in an experiment involving the measurement of gain-switched pulses, which have been compressed by a fiber compressor. The time-spectral product is therefore near-transform-limited. Because the new test for transform-limited pulses one only needs a measurement of the autocorrelation trace and the SHG spectrum at zero delay (where the SHG signal is strongest), the new test has the advantages of pulse-shape independence, high sensitivity, low noise, large dynamic range and short measurement time