Patent ID: 7336414

Claim:
An optical modulation apparatus comprising: bidirectional optical amplifying means for transmitting a continuous wave with a single wavelength bidirectionally, and for providing the single wavelength light with a gain; optical intensity modulation means for carrying out intensity modulation of the continuous wave whose optical power is amplified by said bidirectional optical amplifying means, by a transmission signal with a mark-to-space ratio of practically 1/2; and optical regression means for feeding the continuous wave passing through the intensity modulation by said optical intensity modulation means back to said optical intensity modulation means, or back to said bidirectional optical amplifying means directly, wherein a modulation section loss L (dB), which is defined as a difference between optical power of the input continuous wave to said optical intensity modulation means and optical power of output modulated light from said optical intensity modulation means to a gain G (dB) of said bidirectional optical amplifying means, is set in a range from 0 (dB) to 2G+3.0 (dB).