Extended Reach 10 Gb/s Transmission with an Optical I/Q Modulator Using VCSELs over OFDM-Based Multimode Fiber Link

This paper investigates the possibilities of extending the reach of a 10 Gb/s orthogonal frequency division multiplexing- (OFDM-) based multimode fiber (MMF) link with an optical I/Q modulation technique through vertical cavity surface emitting lasers (VCSELs). The proposed I/Q modulation technique comprises two VCSELs in a 90° hybrid combination to produce I/Q modulated OFDM signal. The results show the excellent performance (in terms of BER and Q factor) of the direct-detection optical- (DDO-) OFDM system with the proposed I/Q modulation in comparison to the direct modulation case. The proposed system is able to achieve worst-case BER of about 1.8616 × 10−3 and Q factor of about 10.9949 dB over a 5 km MMF link. The I/Q modulation technique in the DDO-OFDM system has further been investigated for extending the transmission reach of the MMF link using multispan configuration.

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Theoretical and Experimental Investigation of Direct Detection Optical OFDM Systems with Clipping and Normalization

Journal of Electrical and Computer Engineering ◽

10.1155/2018/1839403 ◽

2018 ◽

Vol 2018 ◽

pp. 1-11 ◽

Cited By ~ 1

Author(s):

Jiang Wu ◽

Zhongpeng Wang

Keyword(s):

Orthogonal Frequency Division Multiplexing ◽

Direct Detection ◽

Single Mode ◽

Superior Performance ◽

Ofdm Systems ◽

Ofdm System ◽

Transmission Scheme ◽

Awgn Channel ◽

Ofdm Signal ◽

Optical Ofdm

A data clipping and normalization technique is employed to improve the performance of the overall direct detection optical orthogonal frequency division multiplexing (DCO-OFDM) system. A detailed analysis of clipping distortion introduced by digital clipping and normalization is provided. The normalization operation amplifies the clipped data signal to the maximum input amplitude of a digital-to-analog converter (DAC). Based on the analysis, a BER formula of the proposed scheme is derived over the AWGN channel and single fiber channel. Performance of an optical clipped OFDM with normalization is assessed through numerical simulations and Monte Claro simulation over the AWGN channel. Theoretical analysis and simulation results both show that the clipping and normalization scheme can greatly improve the BER of an optical OFDM. In particular, BER performance of the proposed transmission scheme was measured in a practical OFDM transmission platform. The measured experimental results show that the clipped and amplified OFDM signal exhibits superior performance in comparison with the conventional OFDM signal. The received sensitivity at a BER of 10−3 for a 4 Gsamples/s (2.6667 Gbits/s) clipped and normalized OFDM signal with clipping ratio of 4 after 100 km standard single-mode fiber (SMF) transmission was improved by 4.3 dB when compared with the conventional OFDM system. The measured results also showed that the clipped OFDM signal exhibits superior performance in comparison with the conventional OFDM signal. Therefore, a clipping and normalization at the transmitter is most effective, and a substantial performance improvement can be obtained by a simple normalization after clipping.

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Performance of a Direct-Detection Spot Mode Division Multiplexing in Multimode Fiber

Journal of Optical Communications ◽

10.1515/joc-2017-0135 ◽

2019 ◽

Vol 40 (2) ◽

pp. 161-166 ◽

Cited By ~ 10

Author(s):

Yousef Fazea ◽

Mustafa Muwafak Alobaedy ◽

Zeyid T. Ibraheem

Keyword(s):

High Speed ◽

Direct Detection ◽

Cavity Surface ◽

Multimode Fiber ◽

Laser Array ◽

Long Distance ◽

Mode Division Multiplexing ◽

Internet Users ◽

Vertical Cavity Surface ◽

Surface Emitting Laser

Abstract Multimode fiber (MMF) regarded as an excellent choice for providing large capacity and high-speed for applications such as data centers due to its adaptability and unwavering quality. The ceaseless development and the increase of Internet users that emphasis on increasing data capacity have promoted mode division multiplexing (MDM) as a promising contender for providing further level of multiplexing freedom by propagating several and dissimilar channels in different mode stream. This paper investigates and analyzes the effects of launching MDM spot mode with various vortex order using vertical-cavity surface-emitting laser array in conjunction with equalization scheme. A capacity of 40 Gbit/s transmitted over MMF long distance of 1500 m has been achieved at a wavelength of 1550.12 nm.

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Hadamard Transform Combined with PTS for PAPR Reduction in Direct-Detection Optical OFDM System

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1061-1062.1194 ◽

2014 ◽

Vol 1061-1062 ◽

pp. 1194-1197

Author(s):

Hui Li ◽

Xu Zhang ◽

Lei Guo ◽

Ye Jun Liu ◽

Xiao Xue Gong ◽

...

Keyword(s):

Orthogonal Frequency Division Multiplexing ◽

Direct Detection ◽

Average Power ◽

Papr Reduction ◽

Hadamard Transform ◽

Ofdm System ◽

Partial Transmit Sequence ◽

Ofdm Signal ◽

Optical Ofdm ◽

Complementary Techniques

High Peak-to-Average Power Ratio (PAPR) of the Orthogonal Frequency Division Multiplexing (OFDM) signal is one of the limitations to the transmission performance of optical OFDM system. In this paper, we propose a novel hybrid PAPR reduction technique called Hadamard Transform Combined with Partial transmit sequence (HTCP). The proposed HTCP scheme combines the merits of two complementary techniques, i.e., Hadamard transform and Partial Transmit Sequence (PTS), to improve the performance of the optical OFDM system in terms of PAPR and Bit Error Rate (BER). Simulation results show that the HTCP scheme has better performance with regard to PAPR and BER compared with the case of applying only the Hadamard transform or PTS technique.

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