Optical waveguide devices and harmonic wave generating devices

An optical waveguide device comprising:

• a ferroelectric layer comprising a ferroelectric material and having a thickness of 4 μm or more and 7 μm or less;
• a supporting body;
• and an adhesive layer adhering a bottom face of said ferroelectric layer and said supporting body, wherein said ferroelectric layer comprises a ridge portion comprising a channel type optical waveguide formed therein, a first protuberance provided on a first side of said ridge portion, and a second protuberance provided on a second side of said ridge portion, wherein inner grooves are formed between said ridge portion and said protuberances, respectively;
• wherein outer grooves are formed outside of said protuberances, respectively;
• wherein said outer grooves are deeper than said inner grooves;
• wherein said ridge portion has a width W1 of 6.6 μm or larger and 8.5 μm or smaller;
• wherein a distance W2 of an outer edge of said first protuberance and an outer edge of said second protuberance is 8.6 μm or larger and 20 μm or smaller;
• wherein said inner grooves have a depth D1 of 2.0 μm or larger and 2.9 μm or smaller;
• and wherein said outer grooves have a depth D2 of 2.5 μm or larger and 3.5 μm or smaller.