Retro-reflective fiber optic filter with triple-fiber ferrule

摘要

A retro-reflective multi-port fiber optic device (100) includes the triple-fiber ferrule (10) with a GRIN rod lens (12) to couple the light. The triple-fiber ferrule (10) with three fibers (18, 20, 22) thereof is attached to the angled facet of the GRIN rod lens (12) and the WDM filter (14) is attached to the opposite side of the lens (12). A reflective mirror (16) is attached next to the other side of the WDM filter (14) opposite to the lens (12) after alignment. The triple-fiber ferrule (10) is used to couple light in and out of the device, and tune the thin film filter center wavelength to the desired ITU grid. Therefore, the coupled-in light from the common input pigtail fiber (18) of the triple-fiber ferrule (10) will be collimated and transmitted unto the WDM filter (14) wherein the part of the in-pass-band light with regard to the WDM filter (14) will transmit through the WDM filter (14), and then successively retro-reflect back by the mirror (16) and further transmit through the WDM band-pass filter (14) again. The retroreflected in-pass-band signal is then coupled into one retro-reflective transmission output fiber/port (22) of the triple-fiber ferrule (10) as a demultiplexed channel. On the other hand, the out-pass-band light with regard to the WDM filter will not transmit through the WDM filter (14) to interact with the mirror (16), but instead be directly reflected back by the WDM filter (14) and coupled into a reflection output fiber/port (20) of the triple-fiber ferrule (14) to be transmitted to the next stage for further demultiplexing other channels.