Optical modulator having ridge and associated structure on substrate

An optical modulator, comprising:

• a Z-axis cut substrate made of LiNbO3 and having formed thereon a ridge, first and second grooves which are positioned on the opposite sides of said ridge, and first and second banks which are positioned on the outer sides of said first and second grooves, respectively;
• a Mach-Zehnder optical waveguide formed on said substrate and including a first Y branching waveguide, first and second arm waveguides which are branched from said first Y branching waveguide and one of which is included in said ridge, and a second Y branching waveguide at which said first and second arm waveguides join together;
• an electrode formed on said substrate and including a signal electrode formed on said ridge and two grounding electrodes formed on said first and second banks, for controlling light propagating in said optical waveguide;
• a buffer layer formed between said substrate and said electrode;
• a silicon layer placed on said substrate;
• and
• first and second recesses formed at symmetrical positions with respect to said ridge on said first and second banks, respectively.

An optical modulator comprising:

• a ridge with first and second grooves positioned on opposite sides of the ridge;
• first and second banks positioned on outer sides of the first and second grooves, respectively;
• first and second recesses in the first and second banks, respectively, the first and second recesses formed at symmetrical positions with respect to the ridge;
• and
• a Mach-Zehnder optical waveguide including a first Y branching waveguide, first and second arm waveguides branching from the first Y branching waveguide, and a second Y branching waveguide at which the first and second arm waveguides join together, one of the first and second arm waveguides, but not the other of the first and second arm waveguides, being on the ridge.

An optical modulator comprising:

• a ridge with first and second grooves positioned on opposite sides of the ridge;
• first and second banks positioned on outer sides of the first and second grooves, respectively;
• first and second recesses in the first and second banks, respectively, the first and second recesses formed at symmetrical positions with respect to the ridge;
• a Mach-Zehnder optical waveguide including a first Y branching waveguide, first and second arm waveguides branching from the first Y branching waveguide, and a second Y branching waveguide at which the first and second arm waveguides join together, one of the first and second arm waveguides, but not the other of the first and second arm waveguides, being on the ridge;
• and
• a z-cut LiNbO3 substrate having an electro-optical effect, wherein the ridge, the first and second grooves, the first and second banks, the first and second recesses and the Mach-Zehnder optical waveguide are formed on the substrate.

An optical modulator comprising:

• a ridge with first and second grooves positioned on opposite sides of the ridge;
• first and second banks positioned on outer sides of the first and second grooves, respectively;
• first and second recesses in the first and second banks, respectively, the first and second recesses formed at symmetrical positions with respect to the ridge;
• a Mach-Zehnder optical waveguide including a first Y branching waveguide, first and second arm waveguides branching from the first Y branching waveguide, and a second Y branching waveguide at which the first and second arm waveguides join together, one of the first and second arm waveguides, but not the other of the first and second arm waveguides, being on the ridge;
• a signal electrode on the ridge;
• first and second grounding electrodes on the first and second banks, respectively;
• and
• a z-cut LiNbO3 substrate having an electro-optical effect, wherein the ridge, the first and second grooves, the first and second banks, the first and second recesses, the Mach-Zehnder optical waveguide, the signal electrode, and the first and second grounding electrodes are formed on the substrate.