| 摘要 |
PURPOSE: To simplify an optical amplifier device by re-transmitting radiation receiving the rotation of a plane of polarization to an amplifier so that the gains of both modes substantially become equal by permitting TE and TM modes to pass through the amplifier the even number of times. CONSTITUTION: The TE and TM modes passing the amplifier 12 forward in the polarization plane depending-type amplifier 12 of multiplex passage (reciprocal passage, for example) are exchanged each other in a return route. Thus, the TE and TM modes obtain substantially equal gains on average after they pass through the amplifier means 12 for the even number ofo times (twice, for example). Radiation emitted from one end parts 12 and 2 of the amplification means 12 rotates the polarization plane by 90 degrees (or odd times) by making it pass through a polarization plane rotation means before it passes through the amplification means 12. Thus, only one amplifier 12 and one coupler 14 are required.
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