Transmission Characteristics Of Doubly Cladding Fiber With An Inner Cladding Made Of Negative Refractive Index Material

In recent years, some abnormal electromagnetic characteristics of negative refractive index material were proposed gradually, which revealed potentially important application value in light and the electromagnetic field,and people's great enthusiasm in study was aroused. In addition, the application of new waveguide and fiber became a hot spot of research at present. The characteristic equation of a doubly cladding W model fiber with an inner cladding made of negative refractive index material was presented by full vector method, and the distinction of the HE₁₁ dispersion curves to the right materials fiber, its mode distribution, dispersion and time delay were demonstrated. These results provided theoretical basis for designing new dispersion compensating fiber and photonic devices.Main contents and innovative points of this paper is as follows:1. A model of doubly cladding fiber with an inner cladding made of negative refractive index material was set up. Full vector method was adopted and characteristic equations was derived by the basic theory of the electromagnetic field.2. The HE₁₁ model B-V dispersion curve was compared and analyzed to conventional materials double-clad fiber, and found that HE₁₁ pattern B-V dispersion curve of negative refractive index materials fiber became steeper and the whole mode distribution band became narrow with inside layer thickness and relative refractive index amplifying. These character- ristics were nearly contrary to routine W type double-clad fiber properties .3. The mode in the specific frequencies is simulated, and a single-mode distribution was raised. Single model transmission was more practical significance in optical fiber communication transmission area.4. The single-mode mode was analyzed, and it was found that single-mode transfer mode only existed in particular parameter scope, and along with the thickness of negative refracting materials increasing, the same pattern appeared different propagation constant at the same frequencies. But the relative refractive index of inner cladding changes, B - V curves moved left approximately, curve shape change very little.5 .By regulating inner layer relative thickness and the relative refractive index, the group delay and waveguide dispersion of HE₁₁ pattern was simulated with numerical way and a flat broadband section near zero dispersion was found. 6. Through regulating inner layer relative thickness and the relative refractive index of single-mode mode, and with numerical simulation analysis, it was found that the diameter of inner cladding had great impact on the dispersion and time delay, the dispersion could reach -158000ps/nm/km and time delay could become very large by increasing the diameter of the inner cladding. These results provided theoretical basis for designing new dispersion compensating fiber and photonic devices.