Patent ID: 7450861
Filing Date: 2008-11-11
Classification: H04B

Abstract:
1. An optical transmitter for generating return-to-zero alternative-mark-inversion (RZ-AMI) optical signals, comprising: electro-absorption modulated laser having a non-linear transfer curve for irradiating an intensity-modulated optical signal on the basis of first non-return-to-zero binary signal; a precoder for precoding a second non-return-to-zero binary signal, said second non-return-to-zero binary signal having information and waveform identical to that of the first non-return-to-zero binary signal; and a Mach Zehnder modulator for phase-modulating the intensity-modulated optical signal on basis of the precoded second non-return-to-zero binary signal to generate a return-to-zero alternative-mark-inversion optical signal, wherein the return-to-zero alternative-mark-inversion optical signal from said Mach Zehnder modulator is a return-to-zero optical signal, a phase of which is adapted to be inverted for every “1” bit, and wherein a reverse bias voltage non greater than −2V is applied to the electro-absorption modulated laser and a zero-crossing point of the intensity-modulated optical signal is set below an intermediate level between a space level and a mark level of the intensity-modulated optical signal.