Theoretical And Simulation Research On All-optical Analog-to-Digital Quantization

Analog-to-digital conversion as the bond linked analog and digital signals, has became an essential component on analog sensors (such as radar, communications equipment and Electronic warfare equipment) and digital signal processing systems. With the popularity of computer, the continuous improvement of detect automation and the development of digital signal processor, analog and digital converters(ADC) performance (such as sample rate, quantization resolution etc.) becomes a limited high-speed digital signal processing applied Signal Technology bottleneck. SO how to improve the quantitative resolution of optical quantization is one of the greatest challenges currently facing for all-optical ADC.This thesis, based on the analysis and discussion of all-optical analog-digital conversion of quantitative methods and optical pulse transmission characteristics in optical fibers, studies the ultra-short optical pulses in highly nonlinear photonic crystal fiber(PCF) and dispersion increasing fiber(DIF) to achieve growth femtosecond pulse soliton self-frequency shift(SSFS) and chirp-free pulse spectrum compression(SC) mechanism, establishes a wavelength converter based on pulse intensity-quantization the physical model. The numerical simulation is used to analysis the quantitative process of the high-speed sampling signal soliton pulses in anomalous dispersion photonic crystal fiber frequency shift effects. By analyzing the several typical spectra compression methods, designing a novel scheme use the dispersion increasing fiber to achieve the pulse compression method after the spectral shift, and studies have shown that this method can effectively improve the quantization accuracy. For the encoding scheme after ADC quantization makes a comparative analysis, the paper proposes optical coding scheme using optical interconnection based on a binary conversion table and simulate it.Simulation system uses a central wavelength of 1550nm,300fs pulse width of the hyperbolic secant soliton as the input pulse, and transmits the pulse signal in the anomalous dispersion photonic crystal fiber as a result of nonlinear effects, will produce soliton self-frequency shift, resulting in the pulse center wavelength shifted to longer wavelengths, the amount of movement up to 140nm. Pulse peak power due to the different wavelengths produce different amount of movement, which can achieve pulse intensity-the corresponding wavelength conversion, different wavelengths represent different intensity pulses, thus completing the process of quantization of the signal. After the pulse frequency shift after another period of growth of optical fiber dispersion, optical fiber by controlling the input power range to achieve the spectrum compression, the compression ratio up to 4 and quantization precision can be compressed more than 5bits.The simulation studies different nonlinear coefficient in the photonic crystal fiber, different input pulse peak power transmission respectively, and analyzes the optical pulse characteristics and fiber parameters on the quantification accuracy.