Hybrid Integration With Efficient Ball Lens-Based Optical Coupling for Compact WDM Transmitters

A photonic integration platform is presented that allows easy manipulation and alignment of a ball lens doublet for efficient coupling between different optical components. The alignment and fixing of the lenses are automated, accurate, and highly scalable for compact parallel optical assemblies. To demonstrate this approach, we built a $4\times25$ -Gb/s compact wavelength-division multiplexed transmitter with low coupling losses of $\sim 2$ dB between lasers and a planar lightwave circuit multiplexing filter.