A $1\times 8$ Splitter Chip With Integrated Fiber Grooves for Reliable Passive Alignment of Fiber Arrays

A 1 × 8 optical splitter with integrated fiberpositioning grooves was fabricated by simultaneous formation of the waveguide cores and grooves. The waveguide cores were realized by intaglio etching of a fused-silica wafer and subsequent core filling, followed by the deposition of an overcladding layer. Fiber-positioning grooves were then formed by wet etching the silica wafer with the use of a highly selective SiNx mask. Passive alignment was accomplished by guiding the fibers into the grooves, which is favorable for automated mass production of splitter modules. The resulting 1 × 8 splitter module exhibited a small insertion loss of <;10 dB, low polarization-dependent loss of <;0.12 dB, and high return loss of >59 dB. It yielded good reliability during a damp heat test at 85°C and 85% humidity, and the insertion loss varied by <;0.3 dB. This simple and reliable approach to fabricating optical splitter modules is expected to greatly reduce the time and costs associated with packaging and enable automation of the process.