Large-signal harmonic and intermodulation distortions in wide-bandwidth GaInAsP semiconductor lasers

Harmonic and intermodulation distortion are two crucial performance parameters of laser diodes in determining their utility in wide-bandwidth analog links. The multimode rate equations are solved numerically to give information on the bandwidth phase, harmonic, and intermodulation distortion of GaInAsP laser diodes at both small- and large-signal levels. The results of the theoretical analysis agree well with experimental results, and show that the effects of both spatial and spectral hole burning are necessary to create an accurate theoretical model that correctly predicts the modulation damping and distortion levels for a range of lateral cavity structures. Anomalous variations in the low-frequency harmonic and intermodulation curves at high modulation levels are explained with this model. The model can be used for any arbitrary input current waveform, and provides information on the output optical spectra which can be used to analyze the propagation of the waveform along an optical fiber.<
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