Measurements and modeling of the harmonic distortion in InGaAsP distributed feedback lasers

Measurements of the second harmonic distortion in 1.3 mu m InGaAsP distributed feedback lasers are reported. At low modulation frequencies ( approximately 50 MHz), the second harmonic distortion exhibits a minimum at a certain bias current. The minimum, in general, is not observed at high modulation frequencies ( approximately 1 GHz). A model of the harmonic distortion, based on the equivalent electrical circuit of the laser, is presented to explain the observed behavior. The spatial hole burning effect in the active region introduces additional nonlinearity, its effects can be significant compared to that of the leakage path.<
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