LIGHT SOURCE AND METHOD FOR TRANSMITTING SPECTRAL CODED DATA

PROBLEM TO BE SOLVED: To obtain a light source which obtain a high output and does not have to use an optical amplifier by consisting of a solid-state laser that is subjected to frequency modulation within one bit period in a solid state which supplies a wide band frequency cyclic output for spectral coded digital data transmission (CDMA method). SOLUTION: A light source that supplies a wide band frequency cyclic output for spectral coded digital data transmission (CDMA method) is constituted of a solid-state laser which is subjected to phase modulation within one bit period. Small high frequency modulation current is added to injection current of the solid-state laser so that the solid-state laser can be modulated within one bit period. The injection current is can be modulated, e.g. in 100 MHz frequency due to the modulation current. As the result of the modulation of the injection current of the solid-state laser, frequency modulation in which spectral width is represented by a modulation index m or a laser output spectrum that is subjected to phase modulation is obtained. The index m almost corresponds to the number of lines.