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Jiang Z.,Huazhong University of Science and Technology | Dai N.,Huazhong University of Science and Technology | Yang L.,Huazhong University of Science and Technology | Peng J.,Huazhong University of Science and Technology | And 4 more authors.
Journal of Non-Crystalline Solids | Year: 2014

Bi-doped and Yb-Bi-codoped SiO2-Al2O3-CaO glasses were prepared, and the effect of Al2O3 composition on the near-infrared (NIR) emission and energy transfer between Yb 3 + and Bin + (Bi NIR emission centers) were investigated. The introduction of Al2O3 into the glass hosts can vary the NIR luminescence centered at 1300 nm and obtain the strongest emission when the concentration of Al2O3 is 15 mol%. Efficient energy transfer from Yb3 + to Bin + is achieved by co-doping of Al2O3. With the increased Al2O3 concentration, the energy transfer efficiency between Yb3 + and Bin + increased at first and then decreased, maximizing (~ 79%) at 8 mol%. It is suggested that the introduction of appropriate Al2O 3 concentration in Yb-Bi-codoped silicate glasses may be an efficient way to realize effective optical amplification with commercially available 976 nm LD pumping. © 2013 Elsevier B.V. All rights reserved. Source


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. Source


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. Source


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. Source


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. Source

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