Optical waveguide element, and optical modulation device and optical transmission device which use same
View Patent ↗An optical waveguide device that can efficiently remove a high-order mode light beam and that is also easily manufactured even in a case where a width or a height of an optical waveguide is small is provided. An optical waveguide device includes a substrate 1 on which a rib type optical waveguide 10 is formed, and a slab waveguide SW disposed close to the rib type optical waveguide 10 , in which roughness of at least a part (SF 1 ) of an upper surface of the slab waveguide SW is larger than roughness (SF 0 ) of a surface of a top portion of the rib type optical waveguide.
1 . An optical waveguide device comprising:
a substrate on which a rib type optical waveguide is formed,
wherein the height of the rib type optical waveguide is 1 μm or less and the width of the rib type optical waveguide is 3 μm or less,
a slab waveguide disposed close to the rib type optical waveguide,
the slab waveguide includes a first slab waveguide that is close to the rib type optical waveguide and that has a lower height than the rib type optical waveguide, and
roughness of an upper surface of the first slab waveguide is higher than roughness of a surface of a top portion of the rib type optical waveguide.
2 . The optical waveguide device according to claim 1 , wherein the slab waveguide includes the first slab waveguide and
a second slab waveguide that is disposed close to the first slab waveguide on a side opposite to the rib type optical waveguide and that has a higher height than the first slab waveguide, and
roughness of an upper surface of the second slab waveguide is higher than roughness of a surface of a top portion of the rib type optical waveguide.
3 . The optical waveguide device according to claim 2 , wherein roughness of an upper surface of the first slab waveguide is set to be the same as the roughness of the upper surface of the second slab waveguide.
4 . The optical waveguide device according to claim 1 , wherein the first slab waveguides are disposed on both sides of the rib type optical waveguide.
5 . The optical waveguide device according to claim 2 , wherein the first and second slab waveguides of the slab waveguide are disposed on both sides of the rib type optical waveguide.
6 . The optical waveguide device according to claim 1 , wherein the slab waveguide is disposed near an input port, a branching part, or a multiplexing part of the rib type optical waveguide.
7 . The optical waveguide device according to claim 1 ,
wherein an input port and an output port of the rib type optical waveguide are disposed on the same end surface of the substrate,
a photo detection unit that detects a light wave propagating through the rib type optical waveguide or radiation light radiated from the rib type optical waveguide is provided on the substrate, and
the slab waveguide is provided between the input port and the photo detection unit.
8 . An optical modulation device comprising:
the optical waveguide device according to claim 1 including an electrode that modulates a light wave propagating through the rib type optical waveguide;
a case accommodating the optical waveguide device; and
an optical fiber through which the light wave is input into the rib type optical waveguide or output from the rib type optical waveguide.
9 . The optical modulation device according to claim 8 , wherein an electronic circuit that amplifies a modulation signal to be input into the optical waveguide device is provided inside the case.
10 . An optical transmission apparatus comprising:
the optical modulation device according to claim 8 ; and
an electronic circuit that outputs a modulation signal causing the optical modulation device to perform a modulation operation.
11 . The optical waveguide device according to claim 2 , wherein a clearance between the rib type optical waveguide and the second slab waveguide is set to 1 μm or less.