| 1. |
- Jiang, Tao, et al.
(författare)
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Investigation of DC-Biased Optical OFDM With Precoding Matrix for Visible Light Communications : Theory, Simulations, and Experiments
- 2018
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Ingår i: IEEE Photonics Journal. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1943-0655. ; 10:5
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Tidskriftsartikel (refereegranskat)abstract
- Orthogonal frequency-division-multiplexing (OFDM) technology is widely used in visible light communication (VLC) to achieve high data rate transmission. However, the traditional direct-current (DC)-biased optical OFDM (DCO-OFDM) VLC systems suffer from the high peak-to-average power ratio (PAPR) which causes signal clipping distortion, and, thus, performance degradation. Furthermore, severe high-frequency fading due to the limited system bandwidth results in poor bit error rate (BER) performance. Precoding matrix (PM) techniques have been proposed to enhance the performance of VLC OFDM transmission, but a little or no work has been carried out in investigating the theory of PM used in OFDM VLC systems. In this paper, we aim to reveal the theory of PM-DCO-OFDM for a VLC system. To figure out the intrinsic laws of a PM method, we investigate the principles of PAPR reduction, clipping distortion optimization, and signal-to-noise ratio (SNR) distribution equalization. Based on the analysis of PAPR, we theoretically proved the simplicity of PM as a method to reduce the possibility of high PAPR by improving the autocorrelation performance of input symbols. The clipping distortion could be improved due to the reduction of high PAPR. Moreover, the relatively uniform SNR distribution can be achieved by PM through equalizing the clipping and channel noise, which is beneficial to improve the BER performance in high-frequency constrained systems. However, the PM method used in a DCO-OFDM VLC system should consider the transmitting power, modulation format, and transmission distance as a whole to achieve the transmission performance improvement. The simulation results demonstrate the complementary cumulative distribution function of PAPR can be reduced similar to 3 dB, while the performance of clipping distortion power and clipping error probability are significantly improved. Furthermore, experiment is carried out with results showing that the PM method can improve the BER performance in the case that VLC OFDM transmission has enough transmitting power, but with the low transmitting power, the PM also can damage the BER performance. The simulation and experiment results are consistent with our theoretical analysis.
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| 2. |
- Liu, Hairong, et al.
(författare)
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Design and analysis of anti-resonant reflecting photonic crystal VCSEL lasers
- 2004
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Ingår i: Optics Express. - 1094-4087. ; 12:18, s. 4269-4274
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Tidskriftsartikel (refereegranskat)abstract
- Anti-resonant reflecting photonic crystal structure is employed in vertical cavity surface emitting lasers (VCSELs) to achieve photon confinement in lateral direction. Such a design is promising in supporting large-aperture single-mode emission. In the configuration, hexagonal arrays of high-index cylinders which run vertically in the cladding region are introduced in the VCSEL's top DBR (p-DBR) mirror region. The transverse modal property of the proposed structure, especially leakage loss, has been theoretically investigated. An optimum design for the minimum radiation loss while maintaining single-mode operation has been discussed in this paper.
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| 3. |
- Liu, Hairong, et al.
(författare)
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Design and analysis of anti-resonant reflecting photonic crystal VCSEL lasers
- 2004
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Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 12:18, s. 4269-4274
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Tidskriftsartikel (refereegranskat)abstract
- Anti-resonant reflecting photonic crystal structure is employed in vertical cavity surface emitting lasers (VCSELs) to achieve photon confinement in lateral direction. Such a design is promising in supporting large-aperture single-mode emission. In the configuration, hexagonal arrays of high-index cylinders which run vertically in the cladding region are introduced in the VCSEL’s top DBR (p-DBR) mirror region. The transverse modal property of the proposed structure, especially leakage loss, has been theoretically investigated. An optimum design for the minimum radiation loss while maintaining single-mode operation has been discussed in this paper.
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| 4. |
- Liu, Hairong, et al.
(författare)
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Optimum design of anti-resonant reflecting photonic crystal vertical-cavity surface-emitting lasers
- 2005
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Ingår i: Chinese Optics Letters. - 1671-7694. ; 3:SUPPL, s. S210-S212
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Tidskriftsartikel (refereegranskat)abstract
- Anti-resonant reflecting photonic crystal structure in vertical-cavity surface-emitting lasers (VCSELs) to achieve photon confinement in lateral direction is introduced. This kind of design is proposed to support large aperture single-mode emission. A proper method to fabricate the proposed structure has also been discussed. Firstly a spacer layer will be fabricated between the active layer and pDBR layer. A hexagonal array of high-index cylinders will be designed by etching and re-growth on the spaced layer. The transverse modal property of the proposed structure has been investigated. An optimum design for the minimum radiation loss by considering of the cylinder diameter has been discussed in this paper.
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| 5. |
- Liu, Hairong, et al.
(författare)
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Theoretical investigation on guiding IR light in hollow-core metallic fiber with corrugated inner surface
- 2010
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Ingår i: Optics Express. - 1094-4087. ; 18:21, s. 21959-21964
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Tidskriftsartikel (refereegranskat)abstract
- Hollow metallic fibers (HMFs) are in general lossy primarily owing to the fact that the guided transverse-magnetic (TM) light sustains a relatively high propagation loss. In this paper, we propose a type of practical hollow-core metallic fiber (HMF) with longitudinally corrugated inner surface for transmitting infrared (IR) light. Simulation results show that the loss of the fundamental TM mode can be easily reduced by 50 similar to 100 times compared to a HMF without surface corrugation. In contrast to the traditional HMF with a dielectric coating, it is shown that the loss of the fundamental TM mode in the proposed HMF is relatively insensitive to the corrugation layer thickness or equivalently the operating frequency.
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| 6. |
- Liu, Hairong, et al.
(författare)
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Theoretical investigation on guiding IR light in hollow-core metallic fiber with corrugated inner surface
- 2010
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Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 18:21, s. 21959-21964
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Tidskriftsartikel (refereegranskat)abstract
- Hollow metallic fibers (HMFs) are in general lossy primarily owing to the fact that the guided transverse-magnetic (TM) light sustains a relatively high propagation loss. In this paper, we propose a type of practical hollow-core metallic fiber (HMF) with longitudinally corrugated inner surface for transmitting infrared (IR) light. Simulation results show that the loss of the fundamental TM mode can be easily reduced by 50~100 times compared to a HMF without surface corrugation. In contrast to the traditional HMF with a dielectric coating, it is shown that the loss of the fundamental TM mode in the proposed HMF is relatively insensitive to the corrugation layer thickness or equivalently the operating frequency.
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| 7. |
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| 8. |
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| 9. |
- Chen, XÍ, et al.
(författare)
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TDHQ Enabling Fine-granularity Adaptive Loading for SSB-DMT Systems
- 2018
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Ingår i: IEEE Photonics Technology Letters. - : Institute of Electrical and Electronics Engineers Inc.. - 1041-1135 .- 1941-0174. ; 30:19, s. 1687-1690
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Tidskriftsartikel (refereegranskat)abstract
- In this letter, we introduce time domain hybrid quadrature amplitude modulation (TDHQ) for the single sideband (SSB) discrete multi-tone (DMT) systems. Experimental results reveal that with a single precoding set and the proposed adaptive loading algorithm, the TDHQ scheme can achieve finer granularity and therefore smoother continuous growth of data rate than that with the conventional quadrature amplitude modulation (QAM). Besides, thanks to the frame construction and the tailored mapping rule, the scheme with TDHQ has an obviously better peak to average power ratio (PAPR).
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| 10. |
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