Study Of Electro-optic Phase Modulation Based Time Lens In Pulse Compression And Fourier Transformation

ABSTRACT:Time lenses are widely used in temporal imaging, optical communication, optical signal measuring, optical signal processing, and have been one of the hottest research spots in optical information technology. The temporal imaging system which using time lens as a key component can generate ultrafast optical pulse, and the temporal Fourier transform system which also use time lens as core part can implement optical pulse measuring and signal processing. Therefore, the optical pulse compression and the Fourier transform have become important subjects of the study of time lens. There are four ways to achieve time lens. Because of its simple structure, flexible parameter adjustment and stable performance, electro-optic phase modulation based time lens has been chose in our study to composed temporal imaging systems and Fourier transform system, and been utilized to make a series of theoretical and simulation studies.Electro-optical phase modulation based time lens is approximated using a cosine modulation voltage of the second phase modulator, so that there is certain aperture limit. In order to optimize the performance, we proposes two efficient methods, parameters modulation and positive voltage method, to increase the aperture of electro-optic phase modulation based time lens. The implementing principle of both methods are theoretically deduced, and the effect of these two methods are verified for the application of optical pulse compression through simulation experiment。In addition, we also use electro-optic phase modulation based time lens implementing temporal4-f system, and analyse the dispersion of its subsystem temporal2-f system which is so called Fourier transform system. It requires that the selecting of dispersion should be confined in a certain dispersive limiting value to confirm performance of the output, and if too low, excessive modulation voltage is required. Finally, we further study the superior performances of temporal4-f system for optical pulse signal processing through functional simulation.The results show that by using electro-optical phase modulation based time lens, the optical pulse signal can be efficiently compressed and Fourier transformed. Therefore, this kind of time lens has a wide range of applications in the field of temporal imaging and optical signal processing.