The low cost, ultra high speed, large capacity and long distance fiber transmission have been the targets of people's pursuit with the explosive growth of information demand. In addition, every milestone in optical communications relies on breakthroughs in basic optoelectronic devices. At present, one of the trends in optical communications is that, like the electrical integrated circuits and on-chip systems, optical communications systems will gradually be integrated into a single optoelectronic chip. Since only integration can realize high density, low cost, low energy consumption, and meet the needs of the future information society green environmental protection. Therefore, low-cost, highly integrated silicon based optoelectronics has flourished in the recent ten years, and has become the focus of research in the field of optical communications and optoelectronics. The State Key Laboratory focus on the key scientific and technical research on silicon based optoelectronics and large capacity optical communication system for many years, and won the National 973 program, the National Natural Science Foundation Project and National 863 program support. The important achievements were achieved on silicon photonics theory, new type silicon-based integrated photonic devices design and technology realization, high speed the optoelectronic-integrated chip, large capacity transmission system. The more than 100 articles (above impact factor 3.0) were published in Physical, Review Letters, Light Science and Application, Optics Letters, Applied Physics Letter and so on.
1) Significant progress in the study of the theory of optical continuum region bound states.
The optical beam can be manipulated precisely, published in the Phys., Rev., Lett., 113, 037401 (2014). This work can clarify the intrinsic physical mechanism of optical continuum region bound states phenomenon, laid the foundation for the realization of accurate control and design of optical beam. In addition, the model provides a simple analysis and research method for silicon photonic devices to achieve continuous adjustable beam bound. It has great application potential in the optical buffer, optical logic, optical signal processing, and quantum information control.
2) Innovating silicon-based optical waveguide device design and breaking the bottleneck of existing technology.
The ultra small on-chip arbitrary rotation angle of the light was first achieved, published in Scientific Reports (Vol. 5, P. 15794, 2015), and was selected as an important achievement in Chinese Optics in 2015. In addition, the ultra small wavelength division multiplexer based on a plasma slot resonator is highly cited for 112 times as ESI high cited paper. The silicon waveguide amplifier and laser made a series of progress. We were invited to write 4 review papers, which were published on the Light: Science & Application (Vol. 4, No. 11, p.e358, 2015) on (impact factor 14), Nature photonics has been cited more than 30 times. Another study published in "China Science: physics mechanics astronomy" (Vol 44, P. 014201 (7), 2015) was award “Chinese science 2016 annual award”, since it has been downloaded 2013 times, cited 15 times up to now.
3) High-speed optoelectronic integrated transceiver.
For the future need of large capacity and high speed optical integrated demand module of optical communication system, the research team, under the support of 863 major projects of the Ministry of science and technology, fabricated silicon based optoelectronic integrated grating, detector, optical modulator, mixer, polarization beam splitter and many other active and passive devices. In May 2015, the first domestic silicon based above100Gb/s rate coherent transmitting and receiving optoelectronic integrated chip was realized, to fill the domestic space. The research results obtained Chinese Optical Engineering Society of science and technology innovation award.
4) High speed coherent optical transmission experiments
We demonstrate 120-Gb/s coherent optical single carrier frequency domain equalization (CO-SCFDE) transmission over 317 km standard single-mode fiber (SSMF), which is the first report of 100G polarization division multiplexed CO-SCFDE operation. We also report the first demonstration of terabit (1.08 Tb/s) coherent optical single carrier frequency division multiplexing (CO-SCFDM) transmission over 3170 km SSMF with EDFA only amplification. For the first time, we introduce Volterra series based nonlinear electrical equalizer into coherent optical communication, which can adaptively compensate for intra-channel fiber nonlinearities. Without requiring prior knowledge of the fiber link parameters, the equalizer is quite efficient and provides enough flexibility when signals are routed differently in optical networks.
5) Long-distance co-propagation of quantum key distribution and terabit classical optical channels.
Quantum key distribution (QKD) generates symmetric keys between two remote parties and guarantees the keys are not accessible to any third party. Wavelength-division multiplexing (WDM) between QKD and classical optical communications by sharing the existing fiber-optics infrastructure is highly desired in order to reduce the cost of QKD applications. Together with the collaborators, we realize the multiplexing and long-distance co-propagation of QKD and terabit classical coherent optical transmission up to 80 km. The data capacity is two orders of magnitude larger than the previous results. The demonstration verifies the feasibility of QKD and classical communication to share the resources of backbone fiber links and thus taking the utility of QKD a great step forward.
6) High speed direct-detection optical transmission experiments.
We report the first single polarization Terabit direct detection WDM transmission on ACP2015 as a PDP paper. We demonstrate 1.728 Tb/s direct detection WDM transmission over 80 km SSMF with half cycle single sideband (SSB) Nyquist 64-QAM signal with a net spectral efficiency record of 3.25 b/s/Hz. We realize 224Gb/s single polarization direct detection transmission over 160km SSMF with Nyquist 16-QAM signal at C-band, which is the first report of C-band single lane 200G direct detection transmission, which sets a record of fiber link length for such systems. We demonstrate single channel direct detection transmission of 112Gb/s Nyquist 16-QAM half-cycle SSB signal over 960km SSMF, which is the longest distance for ~100G direct detection transmission systems at C-band. We report the experimental demonstration of single wavelength terabit free-space intensity modulation direct detection (IM-DD) system employing orbital angular momentum (OAM) multiplexing, which is the first single wavelength terabit transmission and the highest modulation efficiency (48 bits/symbol) ever reported for OAM based direct detection optical communication.