Apparatus and method for measuring the intensity and phase of a light pulse

A method for measuring spectral intensity and an absolute value of spectral phase of a light pulse comprising:

• changing a time delay τ between a measurement target light pulse having an electric field E0(t) changing with a time t and a reference light pulse having an electric field Er(t);
• generating a signal light pulse expressed by a Formula Er(t−τ)+αEr(t−τ)★E0(t), an operator ★ representing general nonlinear mixing, and α representing a coefficient that is proportional to a nonlinear susceptibility in the nonlinear mixing by nonlinearly mixing said reference light pulse having an electric field Er(t−τ) delayed in said changing of the time delay and said measurement target optical pulse;
• inputting said signal light pulse to an imaging spectrum device and outputting a Fourier transform signal expressed by a Formula |F[Er(t−τ)]|2+|αF[Er(t−τ)★E0(t)]|2+2R{αF[Er(t−τ)]*·F[Er(t−τ)★E0(t)]}, F representing a symbol indicating Fourier transform, * representing a complex conjugate, and R representing a symbol indicating a real part;
• obtaining the intensity and phase of said measurement target light pulse from a signal of a second term of said Fourier transform signal representing frequency resolved optical gate signal;
• and
• obtaining the intensity and phase of said measurement target light pulse from a signal of a third term of said Fourier transform signal representing electro-optical sampling signal.