A wavelength tunable laser light source necessary for a Wavelength Division
Multiplexing (WDM)-based optical communication system, and more
particularly, a wavelength tunable laser light source for maintaining a
stable wavelength without a wavelength locker is provided. The wavelength
tunable laser includes an optical fiber and a semiconductor device. The
optical fiber can implement multiple reflection peaks. The semiconductor
device includes a mode size converter section, a gain section and a DBR
mirror section. One facet of the semiconductor device, which is adjacent
to the optical fiber, has an antireflection coating layer. Therefore, the
wavelength tunable laser based on an optical fiber containing multiple
reflection peaks can maintain excellent wavelength stability insensitive
to current injection, temperature, and environments without a wavelength
locker.
