| Owning to photonic crystal fiber's(PCF) flexible design and excellent transmission properties, the flexible distribution of effective refractive index can be achieved by designing different structures of PCFs, which can meet the requirements of various transmission properties. The high birefringence PCFs can be used to make the tunable filter, the dispersion compensation PCFs can be used by the optical fiber communication system for the cumulative dispersion compensation and PCFs with closing to zero and wavelength-flatten dispersion can be used in all wave communication fiber.The purpose of this paper is to study the dispersion and loss properties of high birefringence PCF. In order to obtain the PCF with high birefringence, a low symmetry squeezed model is established, which is composed of the compressed triangular lattice and elliptical air holes. Then, based on the low symmetry model, five kinds of squeezed total reflection type PCF with different structures are designed for the different applications of the dispersion properties. The structure and propagation properties of PCFs are simulated theoretically by full-vector finite element method and super lattice method. The main research contents are as follows:(1) Aiming at the problem of the effect of cumulative dispersion on the optical signal in long-range transmission system, two kinds of high birefringence dispersion compensation squeezed PCFs are designed. In order to compensate the dispersion of a single mode PCF with transmission wavelength at 1.55 ?m, the air holes in the orthogonal direction are reduced in the first structure of PCF. Simulation results show that high negative dispersion can be achieved at broadband range near 1.55?m, birefringence can be reached 3.4 ?10-2 at 1.55 ?m and the loss is very low. In order to compensate the dispersion of all optical communication waveband, we design the second PCF. In this PCF, a small defect air hole is added in the core. Simulation results show that-640 ps/nm/km of high negative flatted dispersion can be realized, the birefringence can be reached 10-2, and the loss is also very low, at all wavelength band range from 1.2 ?m to1.7 ?m.(2) Aiming at the problem of pulse broadening caused by dispersion in single mode PCF, two kinds of squeezed high birefringence PCFs with low dispersion value at 1.55 ?m are designed. In one kind of the structure of PCFs, a small defect air hole is added in the core and the air holes of both three and four layer are added in the cladding layer. Simulation results show that the high birefringence, near zero dispersion, low loss and large effective area are realized. In the other structure of PCF, both four air holes in the middle and the air holes in the orthogonal direction of the cladding are reduced. The simulation results show that zero dispersion value can be realized at near 1.55 ?m, flattened effective area at broadband can be achieved together with 10-2 high birefringence.(3) Aiming at the problem of different wavelength dispersion response and the pulse broadening in wavelength division multiplexing system, a squeezed high birefringence PCF with broadband flattened and low dispersion value are designed. In this PCF structure, we use the graded layer package to increase the flexibility of dispersion control and remove two air holes in the middle of the horizontal direction to increase the asymmetry of the structure. The results show that near zero flatted dispersion and 10-3 high birefringence can be achieved at the broadband from 1.4 ?m to 1.7 ?m. |
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