Numerical Study of a DFB Semiconductor Laser and Laser Array With Chirped Structure Based on the Equivalent Chirp Technology

We propose that a Bragg grating with a chirp profile in a semiconductor distributed feedback (DFB) laser can be designed and fabricated through nonuniform sampling of a uniform grating based on the equivalent chirp technology (ECT). The characteristics, including the relationship between the input current and output power, the light distribution within the laser cavity, the lasing spectrum, and the linewidth, are numerically analyzed and compared with a DFB laser with a true chirped grating. The study shows that the proposed DFB laser with an equivalent chirp provides an identical performance to that of a conventional DFB laser. Based on the ECT, different chirp gratings in a DFB laser array can also be fabricated by simply using different sampling functions, with the grating period in all gratings kept constant. The key advantage of the proposed technique is that a DFB laser or laser array can be fabricated based on the conventional holography technology, which would simplify the fabrication.