10/7/2013 2:56:17 PM
BY by Zhimin Shi
Special guest post during FiO/LS 2013 from the Nanophotonics Technical Group
Dr. Po Dong from Bell Labs / Alcatel-Lucent USA reported in an invited talk some latest results of high-speed silicon photonic integrated circuits for next generation coherent transmission. By integrating different but monolithically compatible materials (silicon, germanium, silicon-nitride and silicon oxide) on one single chip, Bell labs has managed to utilize the advantage of each material to realize various functionalities for encoding and decoding up to 224 Gbit per second on a single chip. For example, Dr. Dong commented that the uniqueness of silicon photonic platform (Silicon-nitride in particular) make polarization control possible on a chip which is difficult for other material platforms. Their solution also includes using germanium for photo-detection, silicon for routing and modulation, and oxide material for input/output coupling. In the device level, Dr. Gong used as an example that silicon micro-ring resonator structures can be used for both intensity and variable phase modulator. Using the Si-Ge-SiN monolithic integration platform, Bell labs has realized transmitting optical signals at 112 Gbit/s over 2500 km of single mode fibers with unprecedented performance. Some further performance challenge would include some low-voltage Silicon modulators with low insertion losses, high coupling efficiency mode converters, reliable high-speed Germanium photo detectors, etc.