To suppress the cost increase of a multiplexer and demultiplexer extracting or inserting a beam of a specific wavelength for a plurality of optical transmission paths by a system multiple-reflecting a propagation beam.
In the multiplexer and demultiplexer, a Gaussian beam is made incident and reflected on optical reflection condensing elements 108-110, the reflection beam is incident on wavelength selection elements 105-107, and the reflection beam from the wavelength selection elements is made incident and reflected on the optical reflection condensing elements different from the above. The optical reflection condensing element and the wavelength selection element are arranged on two virtual planes 111 and 112 facing in parallel. The reflection beam from the wavelength selection element is a multiple reflection beam propagating, while repeating reflection on the two virtual plane. Optical path lengths, leading to the separate wavelength selection element adjacent through reflection of the virtual plane from one wavelength selection element, are all set equal. The beam is input through reflection, from the optical reflection condensing element from the outside of the multiplexer and demultiplexer or propagated as a wavelength multiple signal to the outside of the multiplexer and demultiplexer through reflection from the optical reflection condensing element.
SAKAMOTO TAKESHI
ARAI YOSHIMITSU
Yasuyuki Tanaka
Hiroshi Matsumoto
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