State Key Laboratory of Optical Communication Technologies and Networks

Wuhan, China

State Key Laboratory of Optical Communication Technologies and Networks

Wuhan, China
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Hu Y.,Huazhong University of Science and Technology | Hu Y.,Accelink Technologies Co | Cao W.,Wuhan Research Institute of Posts and Telecommunications | Tang X.,Accelink Technologies Co | And 4 more authors.
Optics Express | Year: 2017

An external cavity tunable laser, which is based on a silicon hybrid micro-ring resonator, is demonstrated. The heat isolate grooves around the rings effectively cuts off temperature crosstalk. Experimental results have shown that the output power of this device can reach 15.5dBm, with a linewidth less than 130 kHz. The tuning range is more than 57nm in C-band with 60 dB side mode suppression ratio (SMSR). © 2017 Optical Society of America.


Gui T.,Jinan University | Li C.,State Key Laboratory of Optical Communication Technologies and Networks | Yang Q.,State Key Laboratory of Optical Communication Technologies and Networks | Xiao X.,State Key Laboratory of Optical Communication Technologies and Networks | And 4 more authors.
Optics Express | Year: 2013

In coherent optical communication systems, the transmitter usually employs an optical in-phase and quadrature (IQ) modulator to perform electrical-to-optical up-conversion. However, some environmental factors, such as temperature and mechanical stress, strongly influence the stability. To stabilize the quality of the transmitted signal, auto bias control (ABC) is essential to keep modulator in optimum bias. In this paper, we present a novel method of ABC for the optical orthogonal frequency division multiplexing (O-OFDM) signal. In the proposed scheme, a small cosine/sine wave dither signal is added on to the I/Q baseband signal, respectively. Based on the power monitoring of the 1st and 2nd harmonics of the dither signal, the biases of the optical IQ modulator for O-OFDM system can be adjusted very precisely. The simulation and experimental results show good performance on locating the optimum bias voltages for the IQ modulator with high precision. © 2013 Optical Society of America.


Zhang M.,State Key Laboratory of Optical Communication Technologies and Networks | Yu J.-G.,State Key Laboratory of Optical Communication Technologies and Networks | Cao Z.-Z.,Hunan University | Chen L.,Hunan University
Guangdianzi Jiguang/Journal of Optoelectronics Laser | Year: 2010

A radio-over-fiber (RoF) system with 56 GHz optical millimeter-wave (mm-wave) generation using an optical phase modulator (PM) based on frequency-doubling technology is proposed and demonstrated experimentally. Firstly, at the central station (CS), a 56 GHz optical mm-wave is generated by a 28 GHz microwave-signal source, which is applied to the phase modulator; secondly, 2.8 Gbit/s OOK downstream data is modulated onto 56 GHz optical carrier and then transmitted over 20 km of standard single-mode fiber (SSMF) to the base station (BS); finally, it would be radiated by a transmission antenna. At the user terminal, baseband signal is retrieved from the downstream data by coherent detector. Experiment results show that the 56 GHz mm-wave signal can be transmitted over 20 km in SSMF with the power penalty less than 1 dB, and 1.1 m via wireless with the power penalty less than 2.5 dB.


Li C.,State Key Laboratory of Optical Communication Technologies and Networks | Li C.,Huazhong University of Science and Technology | Yang Q.,State Key Laboratory of Optical Communication Technologies and Networks | Jiang T.,Huazhong University of Science and Technology | And 6 more authors.
IEEE Photonics Technology Letters | Year: 2012

Multiband discrete Fourier transform spread (DFT-S) is a promising technology to reduce peak-to-average power ratio and mitigate the fiber nonlinearity. We investigate DFT-S coherent optical orthogonal frequency division multiplexing (CO-OFDM) in terms of computational complexity and nonlinearity. With the nonlinearity improvement, 450-Gb/s twoband DFT-S CO-OFDM outperforms conventional CO-OFDM, and is successfully transmitted over a 9280-km fiber link. © 2012 IEEE.


Yang Q.,State Key Laboratory of Optical Communication Technologies and Networks | He Z.,State Key Laboratory of Optical Communication Technologies and Networks | Yang Z.,State Key Laboratory of Optical Communication Technologies and Networks | Yu S.,State Key Laboratory of Optical Communication Technologies and Networks | And 2 more authors.
Optics Express | Year: 2012

Coherent optical OFDM (CO-OFDM) combined with orthogonal band multiplexing provides a scalable and flexible solution for achieving ultra high-speed rate. Among many CO-OFDM implementations, digital Fourier transform spread (DFT-S) CO-OFDM is proposed to mitigate fiber nonlinearity in long-haul transmission. In this paper, we first illustrate the principle of DFT-S OFDM. We then experimentally evaluate the performance of coherent optical DFT-S OFDM in a band-multiplexed transmission system. Compared with conventional clipping methods, DFT-S OFDM can reduce the OFDM peak-to-average power ratio (PAPR) value without suffering from the interference of the neighboring bands. With the benefit of much reduced PAPR, we successfully demonstrate 1.45 Tb/s DFT-S OFDM over 480 km SSMF transmission. © 2012 Optical Society of America.


Li Z.,Jinan University | Xiao X.,State Key Laboratory of Optical Communication Technologies and Networks | Gui T.,Jinan University | Yang Q.,State Key Laboratory of Optical Communication Technologies and Networks | And 8 more authors.
IEEE Photonics Technology Letters | Year: 2013

We propose a novel multiple pilot-carriers assisted direct-detection optical orthogonal frequency division multiplexing (DDO-OFDM) superchannel transmission scheme. With the proposed scheme, a 432-Gb/s transmission over 3040-km standard single mode fiber (SSMF) is successfully demonstrated. The nonlinear effect of correlated/uncorrelated sub-band loading is also investigated. © 2013 IEEE.


You S.,Soochow University of China | Li C.,State Key Laboratory of Optical Communication Technologies and Networks | Yang Q.,State Key Laboratory of Optical Communication Technologies and Networks | Luo M.,State Key Laboratory of Optical Communication Technologies and Networks | And 3 more authors.
IEEE Photonics Technology Letters | Year: 2014

We experimentally demonstrate a sub-band wavelength conversion scheme based on four-wave mixing in high-nonlinear fiber for multiple Tb/s-class superchannel coherent optical orthogonal frequency-division multiplexing networks. Combined with the wavelength selective switches in reconfigurable optical add/drop multiplexers, the overlapped spectra are efficiently relocated and almost seamlessly formed into a new superchannel with very little spectral efficiency degradation. © 2014 IEEE.


Zhang D.,Huazhong University of Science and Technology | Zhang D.,Accelink Technologies Co | Zhao J.,Huazhong University of Science and Technology | Zhao J.,Accelink Technologies Co | And 9 more authors.
Optics Express | Year: 2012

A compact and ultra-narrow linewidth tunable laser with an external cavity based on a simple single-axis-MEMS mirror is presented in this paper. We discuss the simulation of this tunable laser using a two-step hybrid analysis method to obtain an optimal design of the device. A wide wavelength tuning range about 40nm in C-band with a narrow linewidth of less than 50 kHz and wavelength accuracy of ± 1GHz over the entire tuning range can be achieved experimentally. We also conduct several experiments under different conditions to test the tunable laser. This device shows an excellent performance in both single-carrier polarization-multiplexed quadrature phase-shift keying (PM-QPSK) and multi-carrier orthogonal frequency division multiplexing (OFDM) coherent systems. © 2012 Optical Society of America.


Li C.,Huazhong University of Science and Technology | Li C.,State Key Laboratory of Optical Communication Technologies and Networks | Zhang X.,Jinan University | Li H.,State Key Laboratory of Optical Communication Technologies and Networks | And 5 more authors.
IEEE Photonics Journal | Year: 2014

We experimentally demonstrate a 429.96-Gb/s signal transmission over a 400-km standard single-mode fiber within the 50-GHz grid and successfully achieve spectral efficiency as high as 8.63 bit/s/Hz. Orthogonal frequency-division multiplexing/offset quadrature amplitude modulation with 64-quadrature amplitude modulation is selected as the modulation format to provide a "perfect" rectangular spectrum that efficiently reduces the channel crosstalk. No timing or frequency alignment is required for the subbands to form the superchannel. © 2009-2012 IEEE.


Li C.,Huazhong University of Science and Technology | Li C.,State Key Laboratory of Optical Communication Technologies and Networks | Gui C.,Huazhong University of Science and Technology | Xiao X.,State Key Laboratory of Optical Communication Technologies and Networks | And 3 more authors.
Optics Letters | Year: 2014

We report on-chip all-optical wavelength conversion of multicarrier multilevel modulation signals in a silicon waveguide. Using orthogonal frequency-division multiplexing (OFDM) combined with advanced multilevel quadrature amplitude modulation (QAM) signals (i.e., OFDM m-QAM), we experimentally demonstrate all-optical wavelength conversions of 3.2 Gbaud/s OFDM 16/32/64/128-QAM signals based on the degenerate four-wave mixing (FWM) nonlinear effect in a silicon waveguide. The measured optical signal-to-noise ratio (OSNR) penalties of wavelength conversion are ∼3 dB for OFDM 16-QAM and ∼4 dB for OFDM 32-QAM at 7% forward error correction (FEC) threshold and ∼3.5 dB for OFDM 64-QAM and ∼4.5 dB for OFDM 128-QAM at 20% FEC threshold. The observed clear constellations of converted idlers imply favorable performance obtained for silicon-waveguide-based OFDM 16/32/64/128-QAM wavelength conversions. © 2014 Optical Society of America.

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