| 摘要 |
PURPOSE:To miniaturize a laser diode module and reduce cost thereof by arranging the optical axis of a duble refracting lens so as to run parallel with the end surface of a laser diode and be made perpendicular to a junction surface and disposing an optical fiber at the position of image formation of ordinary rays of the double refracting lens. CONSTITUTION:The optical axis 4 of a double refracting lens 2 is arranged so as to run parallel with the end surface 1a of a laser diode and be made perpendicular to a junction surface 1b in the laser diode through a coupling system using one lens. An optical fiber 3 is disposed at the position of image formation of ordinary rays 7. When laser beams from the laser diode 1 are projected to the double refracting lens 2, the positions of image formation of ordinary rays 7 and extraordinary rays 8 change, and extraordinary rays 8 are difficult to be coupled with the optical fiber 3 in comparison with ordinary rays 7, thus improving an excinction ratio. When a constant-polarization fiber is used as the optical fiber, the extinction ratio after a projection from the fiber is further enhanced because the propagation of extraordinary rays can be prevented. Since a polarizer is not employed, a module can be miniaturized and cost thereof is reduced. |
