Recent research activities have been directed to the study of analog lightwave communication systems as CATV systems or phased array radars. Most of these analog systems use laser direct modulation and direct detection. However, analog intensity-modulation (IM) systems place rigid requirements on the linearity of the optical sources [1]. Meeting these requirements, but with a modulation depth that provides an acceptable CNR, is not an easy task, despite the many investigated alternatives, as the use of external modulators and feedforward or predistortion techniques [2]. Another way for transmitting information is offered by the direct frequency modulation (FM) ability of semiconductor lasers.
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