All-Optical Cross-Absorption-Modulation Based Gb/s Switching With Silicon Quantum Dots

• Published in: IEEE journal of selected topics in quantum electronics 2016-11, Vol.22 (6), p.57-69
• Main Authors: Huang, Bo-Ji, Wu, Chung-Lun, Cheng, Chih-Hsien, Hsieh, Cheng-Hsuan, Syu, Shih-Chang, Lin, Yung-Hsiang, Wang, Huai-Yung, Tsai, Cheng-Ting, Chi, Yu-Chieh, Chang, Po-Han, Wu, Chih-I, Lin, Gong-Ru
• Format: Article
• Language: English
• Subjects: Buses (vehicles); Cross-absorption-modulation; Logic; Modulation; Nanostructure; Optical switches; Optical waveguides; Quantum dots; Si quantum dots; Silicon; silicon carbide waveguide; Switching; Waveguide discontinuities; Waveguides; Wavelengths
• ISSN: 1077-260X; 1558-4542
• DOI: 10.1109/JSTQE.2016.2553458

In silicon quantum dots (Si-QDs), the sub-bandgap cross-absorption-modulation (XAM) has been preliminarily observed and confirmed as a new kind of wavelength conversion process to enable ultrafast optical switching. By using the Si-QD doped Si-rich SiC x micro-ring resonator waveguide with a quality factor of 1.7 × 10 4 under an optimized gap spacing of 700 nm away from the bus waveguide, the XAM effect induces a wavelength-converted picosecond all-optical switching between pump and probe signals, which is attributed to a specific free-carrier absorption at probe wavelength caused by the two-photon-absorption induced carriers. The non-degenerate pump-probe analysis also shows a weak Kerr nonlinearity related ultrafast switching response from the changing envelope of the XAM probe pulse at red-shifted wavelength. These observations declare that the nano-scale Si-QDs can provide sufficiently large XAM effect to enable the ultrafast all-optical switching capability for pulsed optical logic applications. To confirm, the Si-QDs doped Si-rich SiC x waveguide modulator-based 1.2 Gb/s all-optical format inversion of a PRZ-OOK data-stream is demonstrated for the first time.