All-optical wavelength division multiplexer (WDM) technology is one promising approach that can be used in the optical communication system for high-speed information transmission. The demand to exploit all-optical logic gates with broadband wavelengths are key elements to employ the WDM for carrying optical signals

In recent years, the all-optical logic gates via four-wave mixing (FWM) in a silicon micro-ring resonator have made great progress, which can realize higher processing speed in ultrafast process.

However, the silicon photonics cannot provide a flexible method for tuning optical characteristics without changing the device’s geometric structure that limiting its practical applications. Are there any methods to realize tunable all-optical logic gates?

A research team led by Prof. Dr. WANG guoxi from Xi'an Institute of Optics and Precision Mechanics (XIOPM) of the Chinese Academy of Sciences (CAS) propose a novel graphene-on-silicon organic hybrid slot micro-ring resonator (GSHMIR) for tunable all-optical logic gates. The results were published in Optics and Laser Technology.

(a) 3D structure and (b) 2D cross section of the proposed GSHMIR. (Image by XIOPM)

The proposed GSHMIR consists of a straight waveguide and a micro-ring resonator waveguide, and they have the same cross-sectional structure. The GSHMIR based on a slot waveguide is filled by the DDMEBT (a kind of polymer) supramolecular and the graphene sheet is covered at the top and bottom of the DDMEBT to realize tunable functionality.

As for processing technic, the device could be obtained by using semiconductor growth and processing techniques. Meanwhile, the DDMEBT and monolayer graphene can be achieved by molecular beam deposition and high-quality chemical vapor deposition (CVD), respectively.

The results reveal that the third-order dispersion will cause distortion of temporal pulses and fourth-order dispersion will lead to waveform broadening. The broadband tunable all-optical AND logic gates for 40 Gb/s RZ-OOK data streams could be achieved based on the GSHMIR.

The proposed structure offers a significant reference for further research of all-optical signal processing, showing the promise for high-speed logical operation in integrated all-optical systems.