All-optical microwave notch filter with flat passband based on semiconductor optical amplifier

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• 作者：Enming Xu ; Xinliang Zhang ; Lina Zhou ; Yu Zhang ; Dexiu Huang
• 关键词：Microwave photonic filter ; Recirculating delay line loop ; Semiconductor optical amplifier ; Cross-gain modulation ; Amplified spontaneous emission
• 刊名：Optics Communications
• 出版年：2009
• 出版时间：15 June 2009
• 年：2009
• 卷：282
• 期：12
• 页码：2297-2300
• 全文大小：355 K

文摘

An all-optical filter structure for interference mitigation of microwave signals is proposed and demonstrated. The structure is based on a recirculating delay line loop (RDLL) and a fiber Bragg grating. The RDLL is comprised of a semiconductor optical amplifier (SOA) followed by a tunable narrowband optical filter and an optical variable delay line. Negative tap is generated using wavelength conversion based on the cross-gain modulation of amplified spontaneous emission spectrum of the SOA. A negative band-pass filter and a broadband all-pass filter are synthesized to achieve a narrow notch filter with flat passband which can excise interference with minimal impact on the wanted signal over a wide microwave range. Experimental results show the notch rejection ratio of 30 dB, good shape factor and tunability.