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Research On Optical Microwave Signal Generation Methods Based On Four Wave Mixing In Highly Nonlinear Fiber

Posted on:2017-01-14Degree:MasterType:Thesis
Country:ChinaCandidate:M ChenFull Text:PDF
GTID:2308330485488067Subject:Optical engineering
Abstract/Summary:PDF Full Text Request
In many microwave systems such as broadband wireless access networks, software defined radio, and radar systems, a high quality millimeter wave source is essential. So far, the generation of microwave signal with a frequency of tens of gigahertz is still a challenge for conventional electronics.Optical method of generating microwave signal has great potential. For optical heterodyne method based on dual wavelength beat frequency, its frequency can be adjusted but spectrum purity is not high. The method based on external modulator has the advantages of adjustable frequency态high frequency spectrum purity and system stability is a highly attractive solution. The realization of optical frequency doubling can also be obtained through nonlinear devices such as nonlinear optical fiber or semiconductor optical amplifier.In this thesis, we investigate the approach of generating microwave signal based on four-wave mixing(FWM) in a highly nonlinear fiber. FWM is a nonlinear effect caused by third order nonlinearity. Four wave mixing is an ultrafast process and is transparent to the data format. It has a variety of applications. The main contents and results are as follows.Firstly, this thesis introduces the theory of four-wave mixing. An approximate solution of the Coupled Amplitude Equations of FWM is given when we the effects of pump depletion is ignored. We obtain the relationship between the gain spectrum of four-wave mixing with the dispersion and fiber length of optical fiber. When considering the effects of pump depletion, the energy will transfer between pump and singnal periodically. When degenerate FWM and nondegenerate FWM are both concerned, the energy will flow between the four optical components.Secondly, frequency doubling and frequency reduction schemes are studied on the Optisystem platform. The frequency of microwave signal of 30 GHz is sextupling to 180 GHz successfully by using the effect of FWM. When the frequency of the microwave drive signal is 5 GHz, a frequency twelvetupled signal of 60 GHz generates. Frequency sextupling and twelvetupling are demonstrated. Finally, frequency conversion from 30 GHz to 10 GHz is obtained with a low bit error rate.Finally, we set up an experimental system to verify the schemes of frequency conversion of microwave. In the experiment of frequency doubling, an microwave signal with a frequency of 18 GHz(six times of the original microwave signal) is obtained successfully and an microwave signal with a frequency of 12 GHz(twelve times of the original microwave signal) is obtained successfully too. In another experiment, we obtain a microwave signal with a frequency of 4 GHz from a microwave signal with a frequency of 26 GHz.
Keywords/Search Tags:Four wave mixing, Highly nonlinear fiber, Optical generation of microwave
PDF Full Text Request
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