| 摘要 |
PROBLEM TO BE SOLVED: To efficiently compensate the spectrum spread of a transmission line according to the kinds of conditions such as a transmitting distance concerning the optical signal of a large capacity by providing a fixed spreading amount so as to roughly compensate the spectrum spread of an optical transmission line and providing a variable spreading amount so as to precisely compensate the spectrum spread of the optical transmission line. SOLUTION: A fixed spread compensator 216 is provided with the fixed spreading amount to roughly compensate the spectrum spread of the optical transmission line. As this compensator 16, a spread compensating fiber obtained by providing refractive index distribution of a special radial direction for the core of a fiber, e.g. to provide the spread of polarities reverse (negative) to the polarity (positive) of the spread of normal SMF or a fiber grating spread compensator obtained by forming a black grid made by the variation of a refractive index at the core of a fiber to provide negative spreading can be used. A variable spread compensator 18 is provided with the variable spread amount to precisely compensate the spectrum spread of the optical transmitter. As the compensator 18, a PLC spread compensator and what varies the spreading amount by giving stress inclination and temperature inclination to fiber grating. |
