MODE PARTITION NOISE OF NEARLY SINGLE-MODE SEMICONDUCTOR-LASERS MODULATED AT GHZ RATES

A new method to calculate very low errors due to mode partition noise in nearly single-mode semiconductor lasers has been developed, The las er is intensity modulated at Ghz rates, The method allows us to obtain the error for a periodic sequence of input bits as a function of the threshold gain difference for different values of the bias current, ab ove and below threshold, injected current in the ON state and modulati on frequency, It is shown that bounds for the error under pseudorandom modulation conditions can be obtained from the periodic and gain swit ching sequences. The required threshold gain difference for an error o f 10(-9) is calculated, and it is shown to increase with the current i n the ON state, We also observe pattern effects at the output of the l aser, for bias current above threshold, due to the pseudorandom sequen ce of input bits. For a special value of the bias current slightly bel ow threshold, these patterns effects are suppressed and the error is i ndependent of the modulation frequency and of the modulation regime.