Research On Optical Temporal Cloak And Its Extending At Telecommunication Data Rate

The invisibility cloak,as magic concept,has recently attracted great interests in many fields due to its mysterious,fascinating and exciting characteristics.The supernatural concept is put on a realistic clothes because of the implementation of the perfect spatial cloak.According to the space-time duality,the spatial cloak is extended to temporal domain,researches has recently described a temporal cloak with or without temporal gap which can hide some events without detection from the observer.On the basis of the theoretical analysis and the experimental demonstration,the major application scenarios of the temporal cloak are constructed,such as optical switch without data bits,interrupt-without-interrupt,improving current communication systems,causality editor and so on.Obviously,one mission critical for these applications of temporal cloak is to create a high-performance temporal cloak at telecommunication data rate,and extend its concept.In this dissertation,two kinds of temporal cloak with superior single-indicator or perfect comprehensive performance are proposed and demonstrated.The major research achievements and contributions are summarized as the followings:(1)A temporal cloak with large fractional cloaking window using time-domain Fraunhofer diffraction is designed and experimentally investigated.After reviewing the basic theory of the space-time duality,it is found that an effective cloaking window can be closed by a dispersive medium with a sufficient dispersion.It can be solve the problem of closing an effective cloaking window using the ultra-short pulse generation to obtain a large fractional cloaking window.By referring to the idea of the spatial cloak based on geometrical optics,a temporal cloak scheme using time-domain Fraunhofer diffraction is proposed.And a temporal cloak with an effective cloaking window of 88 ps,fractional cloaking window of 88%,working rate of 10 Gbit/s is experimentally demonstrated.This is a record-large fractional cloaking window to data.(2)A field-programmable temporal cloak with large effective cloaking window using the swept-frequency filtering-based time-lens is also is designed and experimentally demonstrated.A new application scenario of the temporal cloak is constructed.And the swept-frequency filtering-based time-lens is extended to generate frequency-hopping microwave.Firstly,the working principle of the swept-frequency filtering-based time-lens is introduced.Secondly,the time-lens is proposed by using a broadband frequency comb and an integrated silicon microring driven by a sawtooth electrical signal as s swept-frequency filter.Then,a temporal cloak with a significant extension of effective cloaking window to 3.365 ns is experimentally demonstrated.Besides the record-large cloaking window,the tunability of cloaking window from 3.365 ns to 0.449 ns by changing the repetition rate of driving electrical signals is verified.To break the periodicity of cloaking window,for the first time,a field-programmable temporal cloak is experimentally demonstrated for data shield,enabling to share some public data to the user but conceal other private data in real time.Finally,the swept-frequency filtering-based time-lens is modified to generate the frequency-hopping microwave signal.The proof-of-concept experiments show that the central frequency,bandwidth,frequency order and time sequence length can be flexibly and independently tuned.In addition,the time-bandwidth product of the stepped linear,stepped arbitrary and Costas sequence microwave signal can be over 4.5×10~7.(3)The temporal illusion and temporal mosaic are introduced by extending the concept of the temporal cloak and experimentally demonstrated.By referring to the idea of the extending spatial cloak to spatial illusion and spatial mosaic,the concept of the temporal illusion and temporal mosaic is proposed.From the perspective of function,a temporal illusion and temporal mosaic scheme based on optical fiber system is designed and experimentally demonstrated for the first time to our knowledge.The temporal illusion can transform the output temporal waveforms of a return-to-zero,dark return-to-zero and nonreturn-to-zero event into that of any other event at different illusion bits at a data rate of5 Gbit/s.The temporal mosaic can block some target bits with high-level signal at a data rate of 5 Gbit/s.Finally,a chip system for temporal illusion and temporal mosaic is simply designed.