The limitations of a single mode optical fiber delay line

The overall limitations of a delay system when transmitting multiple microwave signals are examined. At low modulation frequencies modern injection lasers are very linear. As the modulation frequency increases above approximately 200 MHz, the laser will behave as a nonlinear device producing harmonics and intermodulation products of the microwave frequencies that modulated the optical signal. These signals can be as little as 10 dB below the original modulating frequency. The dynamic range is thereby severely limited. A second form of distortion is produced by the chromatic dispersion (phase delay) of the fiber optic. Optical frequency modulation of the laser leads to harmonics of the microwave signal in the detected signal after fiber delay. It is noted that this effect, although smaller, must still be considered