| 摘要 |
PURPOSE:To obtain an optical bidirectional module having good spatial resolution by disposing a lens on a light emitting element and light receiving element side of a large numerical aperture and disposing a polarizing element on an optical fiber side of a small numerical aperture. CONSTITUTION:This optical bidirectional is formed by successively disposing a semiconductor laser 2, a photodiode 3, a lens 4, a diffraction grating 5 and an optical fiber 6. As a result, the light signal emitted from this semiconductor laser 2 is condensed through the lens 4 and is passed through the diffraction grating 5; thereafter, only the diffracted light of zero order is emitted to the optical fiber 6. On the other hand, the light signal propagating the optical fiber 6 is emitted from the optical fiber 6 and is passed through the diffraction grating 5; thereafter, the incidence of the diffracted light of the first order on the photodiode 3 is made possible. In such a case, the lens 4 is disposed on the semiconductor laser 2 side of the large numerical aperture and the exit light from the semiconductor laser 2 is condensed before diffusing, by which the permissible range of the relative positions of the semiconductor laser 2 and the diffraction grating 5 is increased and the resolution efficiency is improved. |
