High-power eight-channel DFB–SOA MOPA array for optical I/O technology

Abstract

We propose and experimentally demonstrate an eight-channel high-power distributed feedback–semiconductor optical amplifier (DFB–SOA) master oscillator–power amplifier array with 100 GHz wavelength spacing for optical input/output (I/O) applications. The gratings are fabricated using the reconstruction equivalent chirp technique to simplify the fabrication process and enhance wavelength control accuracy. An equivalent π phase shift is introduced at 1/5 of the cavity length near the HR facet to enhance the single-mode yield. The slab-coupled optical waveguide structure is employed to reduce internal loss, increase output power, compress linewidth, and support single-transverse-mode operation. Each DFB laser is integrated with a dedicated SOA to enable independent power amplification and channel equalization. High-reflection (HR) and anti-reflection (AR) coatings are deposited on the rear and front facets, respectively, to further enhance the output power. Experimental results show that the eight-channel array achieves precise wavelength control and excellent single-mode characteristics, with an average wavelength spacing of 0.798 nm, side-mode suppression ratios (SMSRs) above 60 dB, and a wavelength deviation of 0.002 nm from the design value. At a bias current of 600 mA for both the DFB and SOA, the output power exceeds 300 mW per channel. The measured Lorentzian linewidth is below 300 kHz, the relative intensity noise is lower than −145 dB/Hz, and the far-field full-width at half-maximum divergence angles are 11.6° × 31.4°. The proposed array demonstrates outstanding performance as a multi-wavelength light source for high-power, high-coherence optical I/O systems.