Generation And Analysis Of Time And Wavelength Interweaved Optical Sampling Pulses

As scientific research keeps developing faster and faster, the bandwidth of analog signals which needs to be studied and processed becomes higher and higher, the electronic analog to digital converter (ADC) which serves as the interface between the analog world and our digital processing technology has become the bottleneck for scientific development. Recently, the proposition of the idea of optical analog to digital converter (OAD) has brought hope and opportunity to the development of analog to digital converters. Optical fiber communication technology has the advantage of high bandwidth, low loss, long transmission distance, low interference, flexible multiplexing techniques. So we can fully incorporate the fiber technology into optical analog to digital converters to increase the effective sampling bandwidth of analog to digital converters.In this paper, we have carefully studied the system architecture and fabrication techniques for time and wavelength interleaved optical sampling pulses which are used as a key technology in Optical Analog to Digital Converters. Our work includes the following contents.We have elaborated on the process of system design and optimization for the generation of time and wavelength interleaved optical sampling pulses. Based on our system performance criteria and the femtosecond fiber laser that we used in our experiment, we have determined to perform WDM right after the femtosecond laser in order to avoid the broadening of femtosecond optical pulses in fiber delay lines. We have decided to employ Faraday Rotation Mirror in WDM system to improve the system polarization sensitivity.We have conducted simulation and experimental study for femtosecond optical pulse spectrum slicing and carried out analysis for the relationship between WDM channel spacing and output optical pulsewidth in the process of spectrum slicing. After analysis and comparison, we chose 200GHz channel spacing WDM for spectrum slicing. On one hand, it could enable the output pulsewidth to be small enough for optical sampling. On the other hand, it could allow us to slice enough wavelengths from the wide spectrum source.We have clearly described the process of making compensation fiber and fiber delay lines using precision reflectometer and high speed oscilloscope. We have completed a 4-wavelength wavelength division and time delay system with the output of time and wavelength interleaved optical pulses.After the design and calculation for 54 times Optical Time Division Multiplexing system and with the help of my classmates, we finished the 54 times Optical Time Division Multiplexing system based on 3×3 couplers. Then we have combined the 54 times Optical Time Division Multiplexing system with the 4-wavelength wavelength division and time delay system to finish the whole system. The system has successfully output 8G sample/s time and wavelength interleaved optical sampling pulses.