Research And Design On Multi-core PCF Broadband Coupler

With the rapid development of optical fiber communication, optical fiber sensing technology, optical fiber CATV, LAN, Optical Access Networks and precision testing systems, the demand of couplers is increasing, especially the broadband couplers. Photonic crystal fiber(PCF) offer a possible design for various optical devices, which exhibits advanced features and flexibly design. Now the research on PCF coupler is a focus. The PCF coupler has many advantages, such as insensitive to the polarization,the short coupling length and the feather of wavelength flatted.In the beginning the concept of photonic crystal fiber is proposed, photonic crystal fiber is a new generation optical fiber, which is based on photonic crystal technology. Compared to conventional optical fiber,PCF shows lots of features,such as no cut-off mode transmission,controlled dispersion, nonlinearity and high flexibility,etc. Then theory of the PCF coupler is discussed and analyzed, it provide a theoretical basis for the design of PCF broadband coupler. The followed is a brief introduction for several numerical simulation method of PCF. Such as plane wave expansion method, effective index method, super cell lattice method, finite difference method, finite element method, beam propagation method, in addition, the software of Matlab and Origin that used in the paper is introduced. On this basis, this paper present an optimized design for dual-core fluorine-doped PCF coupler, the method is using a symmetric structure for an asymmetric structure. The paper mainly uses the beam propagation method to simulate PCF couplers. The result shows that the coupling ration is steady at 50%±0.5%, which exhibit a good feather of wavelength-flatted. In addition, this coupler has the characteristic of a short coupling length, insensitive to technology tolerance and don't introduce the new coupling loss. Another a new design for one-divided-three broadband coupler is proposed. The result shows that the coupler can be used as a one-in-three power divider, and the coupling length doesn't take place with the wavelength is changed in the wavelength range of 1.0μm-1.8μm. This design provide a little theoretical support for the multi-port Broadband Coupler.Finally, the main thesis of paper is gathered up, and some ideas for the study is put forward. With the development of production process the reduction of process cost, we believe that PCF broadband coupler will play an important role in the futuristic optical fiber communication system although the PCF coupler production process is very complicated.