Surface plasmon polariton (SPP) launcher, performing functions of photon-to-SPP conversion and subsequent SPP launching in the required direction, acts as a kind of on-chip SPP source, having great potential applications in the fields of integrated plasmonic circuits and devices. However, the obstacle is how to achieve a wideband, high launching efficiency ratio, and large extinction ratio for unidirectional SPP launcher simultaneously. The all-optical logic discriminator, as one of the important complex all-optical logic gates, functions as discriminating and encoding incident light signals according to wavelength. However, there is no any report about the integrated all-optical logic discriminator at the nano scale, which has seriously restricted the study of ultrahigh speed and ultrawide-band information processing based on integrated plasmonic chips.

Gong’s group proposes a chirped plasmonic crystal configuration to achieve an ultrawide energy bandgap, so that the SPPs can only propagate in one direction with ultrahigh efficiency. The device with a planar microstructure is easy to fabricate, operates over an ultrabroad wavelength range from 690 to 900 nm, and has a large extinction ratio of 30 dB and small feature size of only 3.9 μm simultaneously, which provides an excellent optical source on chip for future optical computing technologies and may pave the way to constructing novel nanophotonic processor architectures. The research is reported as a cover article in the journal of Advanced Optical Materials (Cuicui Lu, Xiaoyong Hu*, Hong Yang, and Qihuang Gong*, “Ultrawide-Band Unidirectional Surface Plasmon Polariton Launchers ”, Adv. Optical Mater. 1, 779 (2013)).

They further integrate the ultrawide-band unidirectional SPP optical source and the nanoscale all-optical logic discriminator on the same chip. Light signals falling within different operating wavelength ranges from 650 nm to 1000 nm are differentiated and endowed with different logic state encodings. Compared with values previously reported, the operating bandwidth is enlarged by one order of magnitude. This work was published in Scientific Reports (Cuicui Lu, Xiaoyong Hu*, Hong Yang, and Qihuang Gong*, “Integrated all-optical logic discriminators based on plasmonic bandgap engineering”, Scientific Reports 3, 2778 (2013)).

The above works are supported by the Creative Research Group Project of the National Natural Science Foundation of China, the National Basic Research Program of China and the State Key Laboratory of Mesoscopic Physics.