Compact monolithic high-power narrow-linewidth multi-wavelength DFB laser array for optical I/O applications

We propose and experimentally demonstrate a compact monolithic four-wavelength distributed feedback (DFB) laser array with 300 GHz spacing, featuring high output power and excellent power uniformity. The lasers are connected in parallel, and a two-stage Y-branch combiner efficiently merges the four wavelengths. An integrated semiconductor optical amplifier (SOA) further boosts the output power. The reconstruction equivalent chirp (REC) technique enables precise wavelength control, while the slab-coupled optical waveguide (SCOW) structure minimizes internal losses and maintains single-mode operation under a wider ridge waveguide. Anti-reflection (AR) and high-reflection (HR) coatings are applied to enhance output efficiency. Experimental results show output powers exceeding 100 mW per wavelength, wavelength deviation below 0.039 nm, side-mode suppression ratios above 35 dB, and linewidths under 530 kHz. The relative intensity noise (RIN) remains below -145 dB/Hz, and clear 25 Gb/s NRZ eye diagrams are obtained using an external LiNbO₃ Mach-Zehnder modulator. These results confirm the proposed laser array as a promising high-power, narrow-linewidth, and power-balanced light source for DWDM optical I/O applications.