Optical filter and optical transmission device
An optical filter includes a spectroscopic element configured to disperse input light, and emit the dispersed input light as spectrum light; and an optical fiber including an end face having a recess, a core having a first face in contact with a bottom of the recess and a second face sandwiched between the first face and a circumference end of the recess, and a clad surrounding the core, wherein in the optical fiber, the recess is irradiated with the spectrum light, the second face is inclined such that a second portion incident from the second face to the core out of the irradiated spectrum light is emitted to the clad, and a first portion incident from the first face to the core out of the irradiated spectrum light is outputted.
1. An optical filter comprising:
a spectroscopic element configured to disperse input light, and emit the dispersed input light as spectrum light; and
an optical fiber including:
an end face having a recess;
a core having a first face in contact with a bottom of the recess and a second face sandwiched between the first face and a circumference end of the recess; and
a clad surrounding the core,
wherein in the optical fiber,
the recess is irradiated with the spectrum light,
the second face is inclined such that a second portion incident from the second face to the core out of the irradiated spectrum light is emitted to the clad, and
a first portion incident from the first face to the core out of the irradiated spectrum light is outputted.
2. The optical filter according to claim 1 , wherein a part of the second portion is refracted on an interface between the core and the clad and emitted to the clad, and other part of the second portion is reflected on the interface.
3. The optical filter according to claim 1 , wherein the circumference end overlaps a boundary between the clad and the core on the end face, or surrounds the boundary.
4. The optical filter according to claim 1 , wherein the recess is hemispherical.
5. The optical filter according to claim 1 , wherein the spectroscopic element changes a center wavelength of the first portion.
6. The optical filter according to claim 1 , wherein
to disperse the input light means that a plurality of components having different wavelengths in the input light are traveled in different directions, and
the spectrum light includes the plurality of components.
7. The optical filter according to claim 1 , wherein the first portion travels in a longitudinal direction of the optical fiber, and is totally reflected on the interface.
8. An optical transmission device comprising:
a light source configured to generate light;
an optical amplifier configured to amplify the light; and
an optical filter including
a spectroscopic element configured to disperse an output of the optical amplifier, the output including the amplified light, and emit the dispersed light as spectrum light,
an optical fiber including:
an end face having a recess;
a core having a first face in contact with a bottom of the recess and a second face sandwiched between the first face and a circumference end of the recess; and
a clad surrounding the core, wherein
in the optical fiber, the recess is irradiated with the spectrum light, the second face is inclined such that a second portion incident from the second face to the core out of the irradiated spectrum light is emitted to the clad, and a first portion incident from the first face to the core out of the irradiated spectrum light is outputted.
9. The optical transmission device according to claim 8 , further comprising: a modulator configured to the light.