Multiple laser diodes non-orthogonal power combining

A power combiner is proposed in which the signaling frames are obtained from a code set formed by nonorthogonal constant-weight codewords. The rate improvements of multiple-diode schemes using the combiner are presented, as compare to a single-diode pulse position modulation (PPM) scheme. Comparisons are made assuming the same alphabet size, and the same peak power per diode. As a function of the number of diodes, optical systems based on this combining scheme are shown to provide data rate improvements about 40% higher than a conventional orthogonal combiner. Because of the reduction of the signaling frame length, this combining technique provides substantial rate improvements as a function of the input alphabet size.<
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