Light-emitting device with precisely tuned and narrowed spectral width of optical output and an optical signal source providing the same

摘要

A light-emitting device whose output wavelength is easily variable is disclosed. The device provides a light-generating portion that emits light by the carrier injection and a variable wavelength filter that sets a specific wavelength lambdar. The variable wavelength filter includes two ring waveguide optical coupled with each other and having optical paths different from each other and at least an electrode to apply an electrical signal to the corresponding ring waveguide. By tuning the specific wavelength lambdar to the wavelength emitted from the light-generating portion, the output wavelength from the light-emitting device may be narrowed.