| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide technology for reducing crosstalk between bits in optical fiber communication with 4-level FSK. <P>SOLUTION: The optical transmitter 10 consists of a precoder 13 for generating a modulated signal which is represented by four types of two-bit signals mapped on four carrier frequencies having low-to-high transition in sequence of (0, 0), (0, 1), (1, 1), (1, 0), from two-channel data signals, and a semiconductor laser 14 for outputting 4-level FSK signals to an optical fiber 30 with direct modulation using the modulated signal. The optical receiver 20 consists of optical filters 211, 212 for separating the 4-level FSK signals into two-channel optical signals, and photoreceivers 24, 25 for detecting a corresponding-channel data signal from each optical signal. The intervals of the four carrier frequencies and the transmissive band width of the optical filter are set to be greater values than 1.2 of a bit rate per channel. <P>COPYRIGHT: (C)2009,JPO&INPIT |
