Semiconductor lasers have been recognized as good light sources because of their small size, light weight, and high output power with a narrow linewidth. However, wavelength stabilization has become an important issue in their applications, such as in dense wavelength-division multiplexing communications and high-power lasers. This wavelength variation is due to changes in the refractive index inside the active region accompanied by fluctuations in the applied current or temperature of the laser. Therefore, typical distributed feedback lasers (DFBs) have an internal thermal electric cooler (TEC) inside the package to maintain the temperature of the laser chip at a specific temperature. However, its role has limitations in the achievement of long-term stability due to the aging effect of the active region through incessant excitation (driving current and device temperature). Further stabilization methods of locking the wavelength to an absorption line of gas cells or to the transmission curve of etalon filters1–4 has been reported. However, the possible wavelengths are predetermined by the available absorption lines of the gas composition ratio in the cells or the angle, thickness, and reflectivity of the filters. In particular, the absorption lines and peaks could be saturated or blurred when the optical power injected into the cells or the filters is too high.