Patent ID: 7197206

Claim:
An optical communication system comprising: a first optical generator and a second optical generator for generating a first single mode light and a second single mode light, respectively, wherein the first single mode light and the second single mode light are orthogonal and non-interfering with each other for the signal transmission, and exist in the same communication channel; a mixing means that mixes the first single mode light and the second single mode light to output a mixed light of orthogonally polarized modes; an optical fiber that delivers the mixed light from the mixing means and gives a random polarization to the mixed light; and reflective optical modulator that has a single in/out port and a polarization-dependent characteristic in optical amplification gain, amplifies and modulates the mixed light after receiving the mixed light from the optical fiber, produces a constantly amplified optical signal regardless of the random polarization of the mixed light in spite of the polarization-dependent characteristic, and reflects the optical signal back toward the optical fiber through the single in/out port.