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    					Large-range tunable fractional-order differentiator based on cascaded microring resonators  | 
  					 
  					  										
						Ting YANG,Shasha LIAO,Li LIU,Jianji DONG( ) | 
					 
															
						| Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology, Wuhan 430074, China | 
					 
										
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													     		                            						                            																	    Abstract  In this paper, we experimentally demonstrate an all-optical continuously tunable fractional-order differentiator using on-chip cascaded electrically tuned microring resonators (MRRs). By changing the voltage applied on a MRR, the phase shift at the resonance frequency of the MRR varies, which can be used to implement tunable fractional-order differentiator. Hence fractional-order differentiator with a larger tunable range can be obtained by cascading more MRR units on a single chip. In the experiment, we applied two direct current voltage sources on two cascaded MRRs respectively, and a tunable order range of 0.57 to 2 have been demonstrated with Gaussian pulse injection, which is the largest tuning range to our knowledge. 
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															| Keywords 
																																																				all-optical devices  
																		  																																				optical differentiator  
																		  																																				optical signal processing  
																																			  
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																																Corresponding Author(s):
																Jianji DONG   
																													     		
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																															Just Accepted Date: 03 August 2016  
																																														Online First Date: 06 September 2016   
																																														Issue Date: 28 September 2016
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