Measurement of the modulation index of a M-Z electro-optical modulator using an optical spectrum analyzer

The frequency response of an electro optic modulator can't be easily measured by the swept frequency method when the modulation frequency is higher than 50 GHz because of the speed limit of the optical detector. Therefore, for higher frequencies, an optical spectrum analyzer provides the best measured modulation index of a Mach Zehnder (M Z) electro optical modulator. The modulation index Γ 1δ and Γ 2δ were calculated using formulas and experimental results in this paper. The experimental results showed the accuracy and utility of the method.