The Design And Characteristics Study Of Two New Nonlinearly Chirped Fiber Grating

With the rapid development of the Optical Fiber Communication, the Fiber Grating has become the most quickly developed optical passive components. Due to many advantages of the Fiber Grating, such as small volume, low loss, good compatibility, cheap price, not affected by electromagnetic interference, it is widely used in fiber optic filters, dispersion compensators, wavelength division multiplexers, fiber lasers, fiber optic sensors and many fields.The first chaper introduces the basic method of researching the non-uniform fiber grating——transmission matrix method, discusses the effects of different fiber parameters on the reflection spectrum and the delay profile characteristics about many kinds of fiber gratings,such as the uniform fiber grating, the apodized fiber grating,the sampled fiber grating, the chirped fiber grating and so on. It better illustrates the role of each parameter in the transmission matrix playing in the whole process.The second chaper designs two new structures of fiber grating ‘nonlinearly chirped + sampled fiber grating’ and ‘discrete nonlinearly chirped + sampled fiber grating’, analyzes the effects that the chirp coefficient, refractive index modulation, grating length, the sampling period, the sampling rate and other parameters have made on the reflection and delay characteristics of these two new structures. The ‘nonlinearly chirped + sampled fiber grating’ has more than five channel in the infrared channel, the channel delay is less than 20ps; the ‘discrete nonlinearly chirped + sampled fiber grating’ have more than ten channel in the communication band, the channel delay can be stabilized at 0ps.The third chaper designs ‘nonlinearly chirped + sampled fiber grating’ structure as a filter and builds a WDM simulation system to test the filter performance in the OptiSystem. It analyzes the future use of the ‘discrete nonlinearly chirped + sampled fiber grating’ structured fiber grating in OCDMA which works as a codec.The results demonstrated that the two new fiber grating structure has multi-channel, undulating and small group delay characteristics, and the structure can reduce the difficulty of manufacturing. It can meet the requirements of WDM and OCDMA system.