Compact hybrid-integrated multi-port multi-wavelength laser source based on high-power DFB laser array for optical I/O technology

We propose and experimentally demonstrate a compact hybrid-integrated multi-port multi-wavelength laser source (MP-MWL) for optical input/output (I/O) technology. A multi-wavelength high-power distributed feedback laser array (DFB LA) with slab-coupled optical waveguide (SCOW) and highly reflective and anti-reflective (HR-AR) coated facet is utilized to achieve simultaneous high-power output of multiple wavelengths. The reconstruction equivalent chirp technique provides highly precise control of the grating phase of the DFB laser and an equivalent π phase shift is introduced to provide single-longitudinal-mode lasing. Employed as a splitter and combiner network, an 8×8 multi-mode interferometer (MMI) on the passive silicon nitride photonic platform contributes to significant bandwidth enhancement. The output from the fiber array (FA) of the proposed MP-MWL has 8 fibers each carrying all 8 wavelengths, for a total of 64 addressable carriers. The photonic wire bonding technique enables the compact and efficient hybrid integration of the LA, MMI and FA. The side mode suppression ratios of all 8 wavelengths are above 42 dB at a 20°C working environment. A wavelength spacing of 100 GHz is achieved, and 87.5% of the wavelengths exhibit a deviation within ± 0.15 nm. Additionally, the relative intensity noise is below -135 dB/Hz, while the Lorentzian linewidth is 379.9 kHz. Furthermore, clear 25 Gb/s non-return-to-zero (NRZ) eye diagrams are obtained for all 64 carriers with the external lithium niobate Mach-Zehnder modulator. The proposed MP-MWL might be applied in optical I/O technology where the dense wavelength division multiplexing (DWDM) technique is required for increasing bandwidth in data centers.