Light emitting device and optical coherence tomography apparatus including same as light source

A light emitting device comprising:

• an optical waveguide including an active layer disposed above a substrate and a pair of clad layers sandwiching the active layer;
• and
• electrodes disposed in a guided wave direction of the optical waveguide,
• wherein the light emitting device drives the electrodes and emits a beam guided to the optical waveguide through an emitting end of the optical waveguide,
• the active layer has at least two gain peaks,
• the electrodes include a first electrode nearest the emitting end and a second electrode next to the first electrode,
• the light emitting device further includes a grating section disposed in a vicinity of the optical waveguide and located between the first and second electrodes,
• the grating section is set so as to reflect or absorb a beam having a wavelength other than wavelengths in a portion between the two gain peaks in a spectrum of the beam generated by driving the second electrode,
• the beam generated by driving the second electrode and having the wavelength selected by the grating section is guided to a region of the optical waveguide where the first electrode is disposed and is combined with a beam generated by driving the first electrode, and
• the light emitting device emits a beam having a peak in a dip portion between the two gain peaks in a spectrum of the beam generated by driving the first electrode through the end face.