Multimode interference device, mach-zehnder modulation device

A multimode interference device comprising:

• a multimode interferometer (MMI) semiconductor mesa for a multimode interferometer, the MMI semiconductor mesa having a first end face, a second end face, a first side face, and a second side face, the first end face and the second end face being arranged in a direction of a first axis, and the first side face and the second side face extending in the direction of the first axis;
• a first semiconductor mesa disposed apart from the first side face of the MMI semiconductor mesa;
• a second semiconductor mesa disposed apart from the second side face of the MMI semiconductor mesa;
• an embedding region covering the MMI semiconductor mesa, the first semiconductor mesa and the second semiconductor mesa, the embedding region having a first opening and a second opening, and the first opening and the second opening being at the first semiconductor mesa and the second semiconductor mesa, respectively;
• a first metal body making contact with the first semiconductor mesa through the first opening;
• and
• a second metal body making contact with the second semiconductor mesa through the second opening,
• the first end face having multiple first ports,
• the second end face having multiple second ports, and
• the first semiconductor mesa, the MMI semiconductor mesa, and the second semiconductor mesa being arranged in a direction of a second axis intersecting the first axis.