I'm not sure that you would find any product on the market which shines the same frequency of light in both directions on a single fiber. All of the bi-directional on a single fiber products that I know of send a different frequency of light in each direction.
Therefore it would seem strange to me to claim that a single strand of fiber can do full duplex, as frequency "B" of light could instead be used to send data in the same direction as frequency "A". So really you are just choosing to allocate some part of the overall capacity of the single fiber to return traffic.
Therefore it would seem strange to me to claim that a single strand of fiber can do full duplex, as frequency "B" of light could instead be used to send data in the same direction as frequency "A". So really you are just choosing to allocate some part of the overall capacity of the single fiber to return traffic.