| 摘要 |
The present invention relates to an apparatus and a method for a Non-Reciprocal Optical Wavelength Filter (NRWF) suitable for bidirectional optical transmissions, communications, and amplifiers. The NRWF of the present invention is composed of (1) a Reciprocal Rotator (RR) rotating the polarization state of the light reciprocally, (2) a non-reciprocal Faraday Rotator (FR) rotating the polarization state non-reciprocally according to the propagating direction, (3) two polarization beam splitters, BC1 and BC2, splitting an unpolarized wave into two orthogonally polarized waves, or combining the two orthogonally polarized waves, and (4) a Wavelength Dependent Polarization Converter (WDPC) changing the polarization state according to the wavelength of light. Accordingly, the NRWF has periodic transfer spectra, and the peaks of the transfer spectrum from Port 1 to Port 2 are located between those of the transfer spectrum form Port 2 to Port 1. Therefore, the NRWF of the invention suppresses multiple reflections in wavelength interleaved bidirectional transmissions. The optical amplifiers with the NRWF of the invention are useful for long-haul bidirectional systems and networks.
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