Time Lens Imaging System And Its Application In Time Hiding And Stream Cipher Secondary Encryption Technology

The processing of high-speed optical signals has always been a difficult issue in the field of signal-processing because it's hard to generate and capture high-frequency optical signals.The time lens imaging system was presented initially for compressing signals so as to obtain higher frequency pulse signals.The successful development of high-speed lasers solves the problem about the generation of high-frequency optical signals.Therefore,time lenses are more widely used in the detection of high-frequency signals,which can greatly lower hardware costs of detection devices.Based on the image-forming principle of the time lens imaging system,the paper deeply studies the system realized by the four-wave mixing effect and deduces imaging formulas.It analyzes the impacts of the high-order dispersion and the initial pulse width of the pump pulse on the imaging quality of the system respectively and verifies relevant conclusions by Matlab program simulation.Then,in the last two chapters,two aspects of the FWM time lens imaging system are researched in details.First,the system can realize the amplification and compression of pulse signals.Based on these two imaging characteristics,the paper explores a method of achieving the temporal cloaking with the help of the system and validates the feasibility of the temporal cloaking realization by program simulation.Second,in view of the inversion characteristics of pulse signals,the system is applied to the stream cipher secondary encryption and decryption technology,and its feasibility is verified by program simulation.In the end,it sums up and provides an outlook of time lens researches.The key researches of this paper involve the following four aspects:1.Starting from the temporal and spatial duality of light and the secondary phase modulation of time lens,the paper studies the basic theory of the system after deducing equations.Then,based on these theoretical researches,it introduces three different time lens implementation methods and compares their advantages and disadvantages.2.The paper deeply studies the FWM time lens imaging system and deduces its imaging formulas.It analyzes the impacts of the high-order dispersion and the initial pulse width of the pump pulse on the imaging quality of the system respectively and verifies relevant conclusions by Matlab program simulation.3.The paper expounds the concept and theory of the temporal cloaking.The amplification and compression of the system's pulse signals can be applied to the temporal cloaking technology,which has two functions: the first time lens imaging system divides the detection beam into high and low frequency parts;the second time lens imaging system restores the high and low frequency detection lights to the original frequency ones.Thus,two time lens imaging systems and the dispersion fiber jointly promote the implement of the temporal cloaking system.At last,it verifies the effect of the temporal cloaking by program simulation.4.Scholars research time inversion characteristics of the time lens imaging system and apply them to the stream cipher primary encryption and decryption technology.But in consideration of its lower theoretical strength and practical strength,to meet more secure application scenarios,the paper proposes a method of achieving the stream cipher secondary encryption and decryption technology based on the system and verifies its feasibility by program simulation.