En-ming Xu,Fei Wang,Pei-li Li.A cascaded microwave photonic filter based on a low-coherence infinite-impulse-response filter[J].Optoelectronics Letters,2013,9(3):165-168 A cascaded microwave photonic filter based on a low-coherence infinite-impulse-response filter Author Name Affiliation E-mail En-ming Xu  School of Optoelectronic Engineering, Nanjing University of Posts and Telecommunications, Nanjing, 210046, China School of Optoelectronic Information, Chongqing University of Technology, Chongqing, 400054, China  enmingxu@gmail.com  Fei Wang  School of Optoelectronic Engineering, Nanjing University of Posts and Telecommunications, Nanjing, 210046, China School of Optoelectronic Information, Chongqing University of Technology, Chongqing, 400054, China    Pei-li Li  School of Optoelectronic Engineering, Nanjing University of Posts and Telecommunications, Nanjing, 210046, China School of Optoelectronic Information, Chongqing University of Technology, Chongqing, 400054, China    Abstract:       A cascaded filter combining active and passive filters is proposed. The active filter acts as a low-coherence infinite-impulse-response (IIR) filter and achieves a sharp frequency response. The low-coherence IIR filter is realized by employing the cross-gain modulation (XGM) of the amplified spontaneous emission (ASE) spectrum of the semiconductor optical amplifier (SOA). The passive filter is an n-section unbalance Mach-Zehnder (UMZ) structure, which is used to increase free spectral range (FSR) and Q factor further. The low-coherence IIR filter cascaded with one section of UMZ passive filter is experimentally demonstrated, and a Q factor of 1268 is obtained. Hits: 4083 Download times: 98 View Full Text    Download reader