摘要 |
An optical device including a lens located between a first port and a second port, and a photodetector having a photodetecting surface located in the vicinity of the second port. The first port and the second port have a first aperture and a second aperture, respectively. The lens has a converging portion for converting a light beam so as to couple the first aperture and the second aperture, and a deflecting portion for deflecting a part of a light beam from the first port to make the part incident on the photodetecting surface. The converging portion and the deflecting portion are integral with each other, for example. By using this optical device, light power can be monitored stably with no polarization dependence.
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