Author:       2016-06-07

The temporal differentiator plays an important role in system controlling, electrocardiograph (ECG) signal monitoring, radar signals analyzing and modern communications. The application of traditional electrical differentiators is limited due to their low processing speed and narrow band. However, the photonic temporal differentiator exhibits large bandwidth, low loss and immunity to electromagnetic interference (EMI). Thus, the investigation on photonic temporal differentiators has been attracting great interest. So far, much effort has been made to improve the performance of photonic temporal differentiator, such as increasing conversion efficiency and accuracy. However, few schemes have been proposed to increase the reconfigurability, such as switching the differentiation type.
Dr. Yuan Yu and professor Jianji Dong, who are from professor Xinliang Zhang’s group, Optoelectronic Device and Integration Lab (OEDI), WNLO, have realized a reconfigurable photonic temporal differentiator which can be switched to any 1st order differentiator by employing a dual-drive Mach-Zehnder modulator (DDMZM). When a relative time delay is introduced between the two arms of the DDMZM, the two optical beams will interfere with each other and a photonic temporal differentiator can be achieved. Adjusting the bias voltage of DDMZM can switch the differentiation type. In the proposed scheme, a pair of polarity-reversed intensity and a pair of polarity-reversed field photonic temporal differentiators are realized. This scheme exhibits advantages of simple structure and good reconfigurability.
On May 20th, 2016, the investigation result entitled “Reconfigurable photonic temporal differentiator based on a dual-drive Mach-Zehnder modulator” was published in “Optics Express” (vol. 24, no. 11, pp. 11739-11748, 2016). The research was supported by the National Natural Science Foundation of China (Grant No. 61501194, Grant No. 61475052), National Science Fund for Distinguished Young Scholars (Grant No. 61125501), the NSFC Major International Joint Research Project (Grant No. 61320106016), Foundation for Innovative Research Groups of the Natural Science Foundation of Hubei Province (Grant No. 2014CFA004), Hubei Provincial Natural Science Foundation of China (Grant No. 2015CFB231), the Fundamental Research Funds for the Central Universities (Grant No. HUST: 2016YXMS025), and Director Fund of WNLO. 

Fig. Four different differentiated waveforms of the 1st order