WDM Source Based on High-Power, Efficient 1280-nm DFB Lasers for Terabit Interconnect Technologies

We present a proof-of-concept eight-channel wavelength-division-multiplexed (WDM) source for future terabit interconnects based on a highly efficient laser array. The array is composed of novel, high-power DFB lasers with record electro-optical efficiency, operating at 1280 nm, with >250-mW laser output power and laser efficiencies of up to 36%. The eight-laser array, with ~100-GHz channel spacing is optically butt-coupled to a planar lightwave circuit that consists of low-loss silicon nitride waveguides clad with silicon oxide for appropriate optical routing. Two types of optical routing are explored: 1) all 8 laser wavelengths are mixed and output into 10 channels via a star coupler and 2) the laser wavelengths are combined into a single output via an arrayed waveguide grating router. The mixed/combined light is then butt-coupled to a fiber array to output the WDM source signal into polarization preserving single-mode fibers. Improvements in insertion loss, particularly from optical butt coupling, will make this approach a viable option for efficient WDM light sources.