Optical device and driving method thereof

A method for driving an optical device, the method comprising:

• generating light in a first light waveguide layer between first and second light generation electrodes of a light generation region of a waveguide path;
• converting a peak wavelength of the light in a second light waveguide layer of a wavelength variable region of the waveguide path, wherein the peak wavelength of the light is converted from a first wavelength to a second wavelength;
• and
• modulating the light in a ring-shaped third light waveguide layer between first and second light modulation electrodes of a light modulation region of the waveguide path,
• wherein the light generation region, the wavelength variable region, and the light modulation region are sequentially arranged in a first direction extending parallel to the waveguide path,
• wherein the first light generation electrode, the first light waveguide layer, and the second light generation electrode overlap each other in a second direction perpendicular to the first direction,
• wherein the first light modulation electrode, the ring-shaped third light waveguide layer, and the second light modulation electrode overlap each other in the second direction,
• wherein a difference between the first wavelength and the second wavelength is defined as a first wavelength difference,
• a free spectral range (FSR) of the modulated light is defined as a second wavelength difference, and
• an integer multiple of the second wavelength difference is the same as the first wavelength difference.