All-optical circuits for signal processing and communication could overcome the inherent electronic bottleneck of increasing operation speed and bandwidth in ultra-fast communication systems . As one of the basic building blocks, optical temporal differentiators that can provide real-time derivation in the optical domain have attracted considerable interest during the past few years due to their potential in the future all-optical information processing systems.Generally, all the optical temporal differentiatorscan be mainly classified into two categories, namely field differentiators and intensity differentiators, respectively. Fiber gratings filter based field differentiators are of great convenience due to the all-fiber structure and are naturally compatible with optical fiber communication systems. What’s more, they present negligible insertion loss and low cost thus are favorable for applications.
However, all previous fiber gratings based differentiators had fixed badwidth at a particular wavelength and couldn’t be easily tuned once the gratings were fabricated. In order to accomplish a wavelength-tunable for various optical pulses at different wavelength, a digitally programmable optical filter is required to shape the spectrum flexibly.
Prof. Tang and his student Zhang Hailiang of WNLO have done research on LCFBG based optical temporal differentiator, In this context, by utilizing our developed digitally controlled waveshaper, we experimentally demonstrate a wavelength-tunable second-order OTD with suitable pulse width.
This study has been published in Optics Letter, Vol.39, pp.2004-2007(2014). This work is supported by the National High-tech R&D Program of China (Grant No. SS2012AA010407 and 2013AA013402), National Natural Science Foundation of China (Grant No. 61107087 and 61331010) and Fundamental Research Funds for the Central Universities, HUST: 2013TS052.