Silicon substrate apparatus and method of manufacturing the silicon substrate apparatus

A method of manufacturing a silicon substrate apparatus including:

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