Optical coupling element and optical device

An optical device comprising:

• an optical amplifier formed on a substrate;
• and
• an optical coupling element formed on the substrate and optically connected to one end of the optical amplifier,
• the optical coupling element including:
• a first optical waveguide connected at one end surface to the optical amplifier, and having a width on the other end surface smaller than a width on said one surface;
• and a second optical waveguide connected one end surface to said one end surface of the first optical waveguide, having a width on the other end surface smaller than a width on said one end surface, and having a shorter length than a length corresponding to 20 wavelengths of an optical signal.

An optical device comprising:

• an optical amplifier formed on a substrate;
• a first optical coupling element formed on the substrate and optically connected to one end of the optical amplifier;
• and
• a second optical coupling element formed on the substrate and optically connected to another end of the optical amplifier,
• each of the first optical coupling element and the second optical coupling element including:
• a first optical waveguide connected at one end surface to the optical amplifier, and having a width on the other end surface smaller than a width on said one surface;
• and a second optical waveguide connected one end surface to said one end surface of the first optical waveguide, having a width on the other end surface smaller than a width on said one end surface, and having a shorter length than a length corresponding to 20 wavelengths of an optical signal.

An optical device comprising:

• an optical amplifier formed on a substrate;
• an optical coupling element formed on the substrate and optically connected to the optical amplifier, and
• an external optical element disposed adjacent to the substrate and optically connected to the optical coupling element,
• the optical coupling element including:
• a first optical waveguide having a width on a side of the external optical element smaller than a width on a side of the optical amplifier;
• and a second optical waveguide connected to the first optical waveguide on the side of the external optical element, and having a width on a side of the external optical element smaller than a width on a side of the optical amplifier and having a shorter length than a length corresponding to 20 wavelengths of an optical signal.

An optical device comprising:

• an optical amplifier formed on a substrate;
• a first optical coupling element formed on the substrate and optically connected to one end of the optical amplifier;
• a second optical coupling element formed on the substrate and optically connected to another end of the optical amplifier;
• a first external optical element disposed adjacent to the substrate and optically connected to the first optical coupling element;
• and
• a second external optical element disposed adjacent to the substrate and optically connected to the second optical coupling element,
• each of the first optical coupling element and the second optical coupling element including:
• a first optical waveguide having a width on a side of the external optical element smaller than a width on a side of the optical amplifier;
• and a second optical waveguide connected to the first optical waveguide on the side of the external optical element, and having a width on a side of the external optical element smaller than a width on a side of the optical amplifier and having a shorter length than a length corresponding to 20 wavelengths of an optical signal.