Highly alignment tolerant and high-sensitivity 100Gb/s (4 × 25Gb/s) APD-ROSA with a thin-film filter-based de-multiplexer.

We investigate and demonstrate a 100-Gb/s (4x25-Gb/s) receiver optical sub-assembly (ROSA) based on avalanche photodiodes and a thin-film filter-based de-multiplexer. The overall alignment tolerances of the ROSA are relaxed to have larger than ± 25 μm by improving optical coupling structure. The receiver sensitivity of each lane is also measured to be less than -22.2 dBm, a record minimum to our knowledge, at the bit error ratio of 10^-12 for 25.78-Gb/s NRZ signal.