【Research Progress】 All-optical 4-bit Gray code generation

Release time:2016-01-31 23:01

Chip-integrated all-optical 4-bit Gray code generation based on silicon microring resonators

All-optical signal processing has attracted widespread attentionfor a long time. Especially, all-optical logic and encoding devices which adopt photons as information carrierscan break the inherent performance limitations of electronic circuit (such as large power consumption and low processing rates), and show the better performances in the optical communication systems(such as parallel processing, high-speed modulation and low latency transmission). Nowadays, with the rapid development of the electro-optic technology, reliable optical encoders have become one of the indispensable core components to guarantee high performance in long-haul transmission and optical interconnection systems. Gray code is one extremely important encoding method due to its convenience and reliable characters of minimization error. Nowadays, Gray code has been widely used in the digital systems, such as image processing and fiber-optic localization. In the past ten years, different optical implementations to encode the Gray code have been proposed, such as using cross gain modulation (XGM) in semiconductor optical amplifiers (SOAs), nonlinear optical loop mirrors, self-phase modulation (SPM). However, these devices with large size and complex structure or special materials are difficult for practical applications in integrated systems.

Li Liu, who is the PHD student of the WNLO and instructed by the Prof. Jianji Dong and Prof. Xinliang Zhang experimentally demonstrate a 4-port passive circuit for encoding 4-bit Gray code on pure silicon platform. The operation principle for this device is the thermo-optic (TO) effect in silicon microring resonator (MRR) whose transmission spectrum could be shifted by injecting strong light power. By combining two independent resonant wavelengths of two MRRs and adjusting their powers in a certain order, all-optical encoder of 4-bit Gray code has been successfully demonstrated. Toward the target of on-chip integration for optical encoder, the proposed device may have important applications in all-optical communication systems.

This work was supported in part by the National Basic Research Program of China (Grant No.2011CB301704); the Program for New Century Excellent Talents in Ministry of Education of China (Grant No.NCET-11-0168); a Foundation forAuthor of National Excellent Doctoral Dissertation of China (Grant No.201139);the National Natural Science Foundation of China (Grant No.11174096 and 61475052); the National Natural Science Foundation of China (Grant No. 11374115 and 61261130586); the Opened Fund of the State Key Laboratory on Integrated Optoelectronics (Grant No. 2011KFJ002). Recently, this work was published in Optics Express (IF: 3.488, vol. 23, pp. 21414, 2015).