Flip-chip bonded 8-channel DFB laser array with highly uniform 400 GHz spacing and high output power for optical I/O technology

In this paper, we proposed and experimentally demonstrated an 8-channel O-band distributed feedback (DFB) laser array with highly uniform 400 GHz spacing and high output power for optical input/output (I/O) technology.The grating phase is precisely controlled, and an equivalent phase shift is implemented in the laser cavity via the reconstruction equivalent chirp (REC) technology.Anti-reflection (AR) and high-reflection (HR) films are coated on the front and rear facets, respectively, to enhance output power.The equivalent phase shift is strategically placed near the HR film facet to improve the yield of the single longitudinal mode.Operating with a 400 GHz wavelength spacing, the proposed DFB laser array meets the continuous wave-wavelength division multiplexing multi-source agreement (CW-WDM MSA) specifications.The proposed DFB laser array is flip-chip bonded to a thin-film circuit with an aluminum nitride (AlN) submount to reduce the thermal resistance and enhance the output power.Compared to the p-side-up structure, the flip-chip bonding design significantly reduces junction temperature by 28% and increases maximum output power by approximately 20%.This design effectively lowers the thermal resistance of the chip and enhances its heat dissipation properties.At a bias current of 110 mA, the laser demonstrates wavelength deviations below 1.579 GHz and side-mode suppression ratios above 50 dB.The far-field divergence is measured at 25.8 30.1, and the Lorentzian linewidth is 3.28 MHz.Increasing the bias current to 250 mA results in a laser output power exceeding 80 mW.Furthermore, the relative intensity noise (RIN) for all 8 channels is below -135.3 dB/Hz.The proposed flip-chip bonded 8-channel high-power DFB laser array demonstrates uniform wavelength spacing, high output power, and stable single longitudinal mode performance, making it a promising candidate for multiple wavelength laser sources in optical I/O technology.