MAXIMUM DYNAMIC-RANGE OPERATION OF A MICROWAVE EXTERNAL MODULATION FIBEROPTIC LINK

We fully analyze the analog performance of an external modulation fibe r-optic link. We express relevant figures of merit-including gain, noi se figure, third-order intermodulation distortion, AM compression, and dynamic range-in terms of the microwave scattering matrices of the mo dulator and detector circuits, and we predict the modulator bias condi tion promoting optimum link performance. Our predictions match the mea sured gain, noise figure, and dynamic range of an experimental 870-930 MHz external modulation fiber-optic link. Maximum spurious-free dynam ic range-77 dB . MHz2/3 (117 db . Hz2/3)-occurs when the modulator is biased at its halfwave voltage, where the optical throughput is nearly pinched off.