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In this paper, the transceiver performance of optical 64QAM-OFDM signals with different sub-car- riers is studied. Firstly, we build a 40Gbit/s optical coherent 64QAM-OFDM transmission system. 64QAM-OFDM optical signals with 16, 32, 64, 64, 128, 256 and 512 sub-carriers are transmitted over 100 km single mode fiber (SMF). Then, the optical spectrum diagrams before and after transmission, the bit error rate (BER) and constellation diagrams of received signals were compared. The simulation results show that, with the number of sub-carriers increasing, the value of PAPR will gradually increase and the quality of the received optical signals will deteriorate. Moreover, with the number of sub-carriers increasing, the computational complexity will increase when digital signal processing (DSP) is used. Therefore, we should choose the optimal number of sub-carriers, and the PAPR influence and BER are also considered for achieving effective transmission.

Orthogonal Frequency division multiplex (OFDM) technology has been widely used in the optical transmission systems, because it has characteristics of effectively against dispersion, eliminating the inter symbol interference (ISI) and flexible bandwidth allocation [

Orthogonal Frequency Division Multiplexing technology, the evolution and development of multicarrier modulation (MCM) technology, has been widely attracted much attention [

In the case of sub-carrier numbers are 128 and 256, we analyzed optical spectral which before and after 64QAM-OFDM signals transmitted over 100 km single mode fiber and after signals through Gauss filter.

We compared constellations and BER in the case of sub-carriers are 16, 32, 64, 128, 256 and 512. The comparison is shown that the BER is gradually increased and the quality of optical receiving signal gradually deteriorated with the increase of the number of sub-carriers in optical coherent 64QAM-OFDM transmission system.

We compared constellations and BER in the case of sub-carrier numbers are 16, 32, 64, 128, 256 and 512. The comparison shown that the bit error rate is gradually increased and the quality of optical receiving signal gradually deteriorated with the increase of the number of sub-carriers in optical coherent 64QAM-OFDM transmission system.

In the study of PAPR for OFDM signal, we should consider two factors: PAPR and computational complexity. We demonstrated the effect of different sub-carriers for PAPR and computational complexity.

Firstly, we analyzed PAPR of 64QAM-OFDM signal in the case of different sub carriers. PARP is described as the peak to average power ratio, which is a ratio function to measure the size of power fluctuation.

We assume that the sequence length is

Different numbers of sub-carriers in optical coherent 64QAM-OFDM transmission system have impact on tran-

sceiver performance. The simulation results show that, the value of PAPR will increase, if the sub-carriers number rise. At the same time, the receiver sensitivity will gradually deteriorate when 64QAM-OFDM optical signals are transmitted over 100 km SMF. Meanwhile, the number increasing of the sub-carriers will lead to the increase of computational complexity. Therefore, selecting suitable sub-carriers number is important. Moreover, we also should consider the influence of BER, PAPR and computational complexity in high speed OFDM optical transmission systems.

This work is partially supported by the National Natural Science Foundation of China (No. 61107064), Innovation Program of Shanghai Municipal Education Commission (No. 15ZZ101), Leading Academic Discipline Project of Information and Communication Engineering (No.XXKZD1605), School Foundation (No. EGD14XQD01) of Shanghai Polytechnic University, College Students’ Science and Technology Innovation Pro- ject of Shanghai Polytechnic University (No. 2016-xjkj-063), and College Student Innovation Activity Plan in Shanghai (No. 2013-sj-cxjh-028).

Changxiang Li,Yufeng Shao,Zhifeng Wang,Junyi Zhou,Yue Zhou,Wenzhe Ma, (2016) Optical 64QAM-OFDM Transmission Systems with Different Sub-Carriers. Optics and Photonics Journal,06,196-200. doi: 10.4236/opj.2016.68B032