Silicon substrate device and its manufacturing method

A method of manufacturing a silicon substrate apparatus including:

• forming in a first silicon substrate a first narrow rectangular groove having a rectangular cross section, and a second narrow rectangular groove substantially orthogonal to said first narrow rectangular groove and having a rectangular cross section;
• forming in a second silicon substrate a third narrow rectangular groove at a position facing said first narrow rectangular groove and having a rectangular cross section;
• placing a device substrate including a frequency conversion device in said second narrow rectangular groove, so that said frequency conversion device is located where said first and second narrow rectangular grooves are orthogonal to each other;
• and
• forming a rectangular waveguide, which includes said first narrow rectangular groove and said third narrow rectangular groove and in which a received high frequency signal propagates and is incident on said frequency conversion device, by bonding said first silicon substrate on which said device substrate is located, to said second silicon substrate, so that said first narrow rectangular groove opposes said third narrow rectangular groove.