Novel design of Raman amplifier pump module

Raman amplifier is one of enabler technologies for next generation optic communication system, especially for 40Gbit/s based system. To get wide commercial application, however, there are several obstacles that should be overcome. Main problems of distributed Raman amplifier include reliable and low cost design, safety operation, automatic gain control, signal power monitoring and so on. For Raman gain is relevant to relative polarization state between pump light and signal light over fiber, two pumps with same wavelength and same power but perpendicular polarization state are often required. In general, this will lead to more components, high cost, complexity and big size. On the other hand, this will limit the number of pump wavelength that can be used, and limit Raman amplifier's performance. For the first time, we invented two kind of key component to solve the problem thoroughly, one component is micro optic depolarizer, and another is depolarizer-isolated PBC hybrid component. Based on these two key component, we demonstrated a novel flexible and low cost structure design of Raman pump module. We also test new Raman pump module, which show low DOP and very low PDG gain in backward or forward pumping scheme.