Analysis of sinusoidally modulated chirped laser pulses by temporally encoded spectral shifting.

We present an analytical formalism elucidating how information is stored in chirped optical probes by describing the effects of sinusoidal temporal modulations on the electric field. We show that the modulations produce spectral sidebands which can be interpreted as temporal sidebands due to the time-wavelength mapping, an effect we call temporally encoded spectral shifting (TESS). A derivation is presented for the case of chirped-pulse spectral interferometry showing how to recover both the amplitude and the periodicity of the modulation from a Fourier transform of the interferogram. The TESS effect, which provides an intuitive picture for interpreting pump-probe experiments with chirped pulses, is illustrated for probing wakefields from a laser-plasma accelerator.