Frequency-resolved optical gating at 1.5 μm using the Kerr nonlinearity in optical fibres

Frequency-resolved optical gating (FROG) is rapidly becoming a routine measurement technique for the characterisation of ultrashort light pulses, and a number of different experimental schemes based on nonlinear processes in bulk materials have been demonstrated [1]. As the use of FROG becomes more widespread, there will be increasing demand for additional convenient geometries for particular experimental applications. In this paper, we use the Kerr nonlinearity in 20 m of dispersion-shifted fibre as the nonlinear process for a novel Fibre-FROG geometry, and characterise the intensity and phase of picosecond pulses around 1.5 μm. The results are found to be in excellent agreement with results obtained using a standard second-harmonic generation (SHG) FROG technique.