| 摘要 |
PROBLEM TO BE SOLVED: To provide a spectral device for keeping a small loss of signal light even when the number of channels is large.SOLUTION: The wavelength band of the light transmitting through an optical filter 14 is ABC to travel to the right side in the figure. The light of a wavelength band DEF reflected by the optical filter 14 travels to the lower left side in the figure. Subsequently, for the light of transmitted light (band ABC) and reflected light (band DEF), a second optical filter that transmits only a wavelength band corresponding to a single channel is used. |
