Photonic generation of microwave waveforms with wide chirp tuning range

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• 作者：Jia Haur Wong^a ; ^{wong0779@ntu.edu.sg} ; Huan Huan Liu^a ; Huy Quoc Lam^b ; Sheel Aditya^a ; Junqiang Zhou^a ; Peng Huei Lim^a ; Kenneth Eng Kian Lee^b ; Kan Wu^a ; Kin Kee Chow^a ; Perry Ping Shum^a
• 关键词：Microwave photonics ; Chirped pulse generation ; Fiber-Bragg-gratings ; Frequency-to-time mapping ; Dispersion
• 刊名：Optics Communications
• 出版年：2013
• 出版时间：1 September, 2013
• 年：2013
• 卷：304
• 期：Complete
• 页码：102-106
• 全文大小：1030 K

文摘

We show analytically as well as demonstrate experimentally an approach to generate microwave waveforms with wide chirp tuning range. The approach is based on the interference of two temporally-stretched pulses which are time-delayed with respect to each other and having different frequency chirp. This approach is realized by an unbalanced Mach Zehnder Interferometer (MZI) incorporating a linearly-chirped fiber-Bragg-grating (LCFBG) whose group-delay-dispersion (GDD) can be tuned across a wide range. In general, tuning the GDD of the LCFBG changes the chirp rate of the generated microwave waveform and tuning the relative time-delay between the interferometer arms changes the center frequency of the generated microwave waveform. Balanced photodetection is also implemented to obtain DC-free microwave waveforms. Based on this approach, we demonstrate the generation of microwave waveforms with different center frequencies and with the chirp rates ranging from¡«?126.7 GHz/ns to ¡«+120.8 GHz/ns, including the zero-chirp case.