Asymmetric property in the lasing spectrum of the phase-shifted distributed feedback laser with linearly chirped grating

The phase-shifted distributed feedback (DFB) semiconductor laser with linearly chirped grating based on reconstruction equivalent chirp (REC) technique is theoretically analyzed and experimentally demonstrated for the first time. The asymmetric property of the lasing spectrum is analyzed according to the normalized threshold gain, and the different spectra from the rear and front side of the laser are compared. The fabricated laser has small lasing wavelength shift of 7pm/mA. It is the simplest way to realize chirped grating on semiconductor lasers to our knowledge.