| 摘要 |
<p>The invention provides a small optical device with which incident light can be demultiplexed. The optical device includes a demultiplexing portion (4) (first optical member) separating TE waves and TM waves of incident light of a wavelength lambda and an optical fiber (1) (optical input portion) inputting incident light into the demultiplexing portion (4). The demultiplexing portion (4) has a periodically changing refractive index. The angle defined by the first reciprocal lattice vector alpha 1 and the second reciprocal lattice vector alpha 2 of the demultiplexing portion (4) at the wavelength lambda is not greater than 90 DEG . In the direction of the first reciprocal lattice vector alpha 1 the wave number of the TE wave is larger than the wave number of the TM wave. In the direction of the second reciprocal lattice vector alpha 2 the wave number of the TE wave is smaller than the wave number of the TM wave. The optical fiber (1) inputs the incident light in a direction that is parallel to a plane including the first reciprocal lattice vector alpha 1 and the second reciprocal lattice vector alpha 2. The device can also be used in a wavelength interleaver or a polarisation-dependent or polarisation-independent optical isolator. <IMAGE></p> |
