Patent ID: 6842467

Claim:
A laser apparatus for generating laser light to be transmitted through an optical transmission system, comprising: a laser that emits light that is substantially linearly polarized when in use; a quarter wave retarder plate that is positioned with respect to the laser so that: light emitted by the laser is circularly polarized by the wave reader plate so as to have a predetermined handedness before reaching an optical transmission system; and light reflected back toward the laser has a linear polarization, after passing through the quarter wave retarder plate a second time, eat is orthogonal to the linearly polarized light emitted by the laser; and a linear polarizer that is positioned between the laser and the quarter wave retarder plate so as to: permit the linearly polarized light emitted by the laser to pass through the linear polarizer; and block light reflected back toward the laser by the optical transmission system that has a linear polarization that is orthogonal to the linearly polarized light emitted by the laser.