Optical device and optical communication device
An optical device includes an optical waveguide, a buffer layer that is layered on the optical waveguide, and an electrode that is arranged on a surface of the buffer layer that is layered in a part near the optical waveguide and that applies an electric signal to the optical waveguide. The optical device further includes a slit that is formed in the buffer layer, that extends from the surface of the buffer layer to a vicinity of the optical waveguide, and that is filled with part of the electrode.
1. An optical device comprising:
an optical waveguide;
a buffer layer that is layered on the optical waveguide;
an electrode that is arranged on an arrangement face of the buffer layer that is layered in a part of a side face of the optical waveguide so as not to overlap the optical waveguide under the electrode and that applies an electric signal to the optical waveguide; and
a slit that is formed in the buffer layer and that is filled with part of the electrode,
wherein the slit has a structure to extend in a vertical direction from the arrangement face of the buffer layer to a vicinity of the side face of the optical waveguide so as to set a tip of the part of the electrode close to the side face of the optical waveguide in which a first distance between the tip of the part of the electrode in the slit and the optical waveguide is shorter than to a second distance between the electrode on the arrangement face and the optical waveguide.
2. The optical device according to claim 1 , wherein the optical waveguide is a rib waveguide that has a core and a slab, and
the slit extends from the arrangement face of the buffer layer on which the electrode is arranged to a vicinity of a side face part of the core of the rib waveguide.
3. The optical device according to claim 1 , wherein the optical waveguide is a channel waveguide, and
the slit extends from the arrangement face of the buffer layer on which the electrode is arranged to a vicinity of a side face part of the channel waveguide.
4. The optical device according to claim 1 , wherein the slit extends from the arrangement face to a middle of the buffer layer.
5. The optical device according to claim 1 , wherein the electrode includes:
a signal electrode that is arranged on the arrangement face of the buffer layer that is layered in a part on one of side faces of the optical waveguide; and
a ground electrode that is arranged on the arrangement face of the buffer layer that is layered in a part on an other side face of the optical waveguide, and
the slit is formed in the buffer layer such that the slit extends from the signal electrode to a vicinity of the optical waveguide and is filled with part of the signal electrode.
6. The optical device according to claim 5 , wherein the slit includes:
a first slit that extends from the arrangement face on which the signal electrode is arranged to the vicinity of the optical waveguide; and
a second slit that extends from the arrangement face on which the ground electrode is arranged to the vicinity of the optical waveguide, and
the first slit is structured such that the first slit is closer to the optical waveguide than the second slit.
7. The optical device according to claim 1 , wherein the optical waveguide is an optical waveguide of film lithium niobate (LN) crystal.
8. The optical device according to claim 7 , wherein the optical waveguide is formed using an X-cut substrate of the film LN crystal.
9. The optical device according to claim 1 , wherein the electrode is a direct current (DC) electrode.
10. The optical device according to claim 1 , wherein the electrode is a radio frequency (RF) electrode.
11. An optical communication device comprising:
a processor configured to execute signal processing on an electric signal;
a light source configured to generate light; and
an optical device configured to modulate the light that is generated from the light source using an electric signal that is output from the processor,
wherein the optical device includes:
an optical waveguide;
a buffer layer that is layered on the optical waveguide;
an electrode that is arranged on an arrangement face of the buffer layer that is layered in a part of a side face of the optical waveguide so as not to overlap the optical waveguide under the electrode and that applies an electric signal to the optical waveguide; and
a slit that is formed in the buffer layer and that is filled with part of the electrode, wherein the slit has a structure to extend in a vertical direction from the arrangement face of the buffer layer to a vicinity of the side face of the optical waveguide so as to set a tip of the part of the electrode close to the side face of the optical waveguide in which a first distance between the tip of the part of the electrode in the slit and the optical waveguide is shorter than to a second distance between the electrode on the arrangement face and the optical waveguide.
12. An optical device comprising:
an optical waveguide;
a buffer layer that is layered on the optical waveguide;
an electrode that is arranged on an arrangement face of the buffer layer that is layered in a part of a side face of the optical waveguide so as not to overlap the optical waveguide under the electrode and that applies an electric signal to the optical waveguide; and
a slit that is formed in the buffer layer and that is filled with part of the electrode,
wherein the slit has a structure to extend obliquely from the arrangement face of the buffer layer toward a side face part of the optical waveguide so as to set a tip of the part of the electrode close to the side face of the optical waveguide in which a first distance between the tip of the part of the electrode in the slit and the optical waveguide is shorter than to a second distance between the electrode on the arrangement face and the optical waveguide.