Reduction of modal noise in high-speed short-distance computer data links by an electrical signal

Measured and calculated data on the tradeoffs between modal noise reduction and intermodulation penalty are presented. The authors quantify how a high modulation bandwidth and optical power can be obtained using conventional high-speed semiconductor lasers, by combining a sinusoidal auxiliary microwave signal with the normal data signal. How the characteristics of the laser diode determine the optimum values of the auxiliary carrier parameters is shown. Some results of optical data link simulations are presented. A 2.4-Gb/s transmission experiment shows an improvement of the bit error rate due to the microwave signal. >