The Si waveguide 305 includes a first conductivity-type Si layer 301 and an intrinsic Si layer 302, and a second conductivity-type light-absorption layer 303 is partially formed on an area thereof. The method includes retrieving, by a computing system, a list of candidate services. An unused guide tube is cut and serially connected to a branch guide tube leading to the new service location. This is achieved by means of a very simple and flexible implementation. Further, the rate at which hydrocarbons are fed into the reactor is equivalent to the rate at which the hydrocarbons react for given synthesis temperature. Also, described are methods of making and using such polymeric compositions.