Optical modulation element
An optical modulation element 100 includes a rib type optical waveguide that includes a rib portion 112 that has a P-N junction, a P-type slab area 114 that continuously extends from a P type area of the rib portion 112 , and an N-type slab area 116 that continuously extends from an N type area of the rib portion 112 . A first thin film 130 is formed on the P-type slab area 114 and is made of a material having an electron affinity that is different from that of the P-type slab area 114.
1. An optical modulation element comprising:
a rib type optical waveguide that includes
a rib portion that has a P-N junction,
a P-type slab area that continuously extends from a P type area of the rib portion, and
an N-type slab area that continuously extends from an N type area of the rib portion; and
a first thin film that is formed on the P-type slab area, that is isolated from a dopant and that is made of a material having an electron affinity that is different from an electron affinity of the P-type slab area, a two-dimensional hold gas (2DHG) being formed in the first thin film.
2. The optical modulation element according to claim 1 , wherein the first thin film is formed with a gap from a side wall of the rib portion.
3. The optical modulation element according to claim 1 , further comprising a second thin film that is formed on the N-type slab area and that is made of a material having an electron affinity that is different from an electron affinity of the N-type slab area.
4. The optical modulation element according to claim 3 , wherein the second thin film is formed with a gap from a side wall of the rib portion.
5. The optical modulation element according to claim 1 , wherein the rib type optical waveguide includes Si, and the first thin film includes Ge.