Add-drop Filter By Coupling Between Micro-nano Fiber Ring And Side Polished Fiber

In the field of optical fiber communication, optical add-drop filter is animportant all-optical devices, and its main function is, the reception and some of thespecific wavelength channels transmitted from the ground to selectively transmit lightpath upload and download locally, while not affect other transmission wavelengthchannel. In order to achieve all-optical communication, people often need opticaldevices with structure of more simpler, smaller and stable performance. Add-dropfilter by coupling between micro-/nano-fiber ring and side polished fiber just has thischaracteristics of micro-/nano-fiber ring which has a simple structure, function, smallvolume and so on. Recently, a variety of micro-nano optical devices with continued tobe reported, the optical system based on micro-nano fibers as possible, but theproblem of micro-nano fiber optic connection systems and conventional fiber opticsystem is one of the bottlenecks in the application of micro-nano fiber system. Inpractice, the micro-nano fiber with a conventional fiber-optic systems required(communication or sensor) connected to the system, and thus the effective micro-andnano fiber coupling system between a conventional fiber-optic system has becomeone of the key micro-nano fiber system applications. As add-drop filter by couplingbetween micro-/nano-fiber ring and side polished fiber don’t have additional designcoupled with standard optical fiber, so it provides a more simple and effectivesolution to connect micro-nano fiber system with existing optic fiber interconnectionsystems.A new method that combined the manner of hand-drawn by the kerosene lampheating with the manner of mechanical drawing by the stepping motor has been putforward experimental in this paper. First, we have obtained excellent evenness MNFof length of20~100mm and diameter of1~5m by the method of manually drawing,then knot the drawn MNF by the three-dimensional translation stage which wasdriven by the stepping motor to form a ring. Because of the ring can be accuratelyadjusted by the stepping motor, the resonant frequency of the ring has a largecontrollability. Using this method we have fabricated different parameters of MNF ring which the MNF diameter was1~5m and the ring diameter was100~900msuccessfully, and the test spectrum showed that they both have good resonancecharacteristics. In addition, since the input port and the output port are all the pigtailof standard single mode fiber, the device manufactured by this method has theadvantages of easy production of micro-nano optical devices. A novel add-drop filterbased on direct coupling between micro-/nano-fiber ring and side-polished fiber isproposed and demonstrated. Experiment results shows that this kind of filter not onlycan realize connection of the MNF optical system with conventional optical system,but also can function as add-drop filter between the two optical systems. Themaximum extinction ratio of drop port can achieved to be7.5dB as a drop filter, whilemaximum extinction of add port can be of4.8dB as a add filter. Furthermore, theinfluence of different ring diameters on the coupling between the two optical systemswas numerically and experimentally investigated. The conclusion of the investigationis that when the diameter of MNF is fixed at6μm and the diameter of MNF ringreaches to be580μm, coupling efficient of the MNF ring and SPF will be maximumand the influence of the coupling on the Q value and fineness o the ring will reachminimum simultaneously. The innovations of this research are as follows:1. We have put forward a new method that combined the manner of hand-drawnby the kerosene lamp heating with the manner of mechanical drawing by the steppingmotor;2. We have realized the coupling between micro-/nano-fiber ring andside-polished fiber for the first time, and obtained their optical spectra.3. We have realized the function of up/down filtering based on the couplingbetween micro-/nano-fiber ring and side-polished fiber successfully.