Direct and External Intensity Modulation in OFDM RoF Links

Author

Khwandah, Sinan A. ; Cosmas, John P. ; Glover, Ian A. ; Lazaridis, Pavlos I. ; Prasad, Neeli R. ; Zaharis, Zaharias D.

Author_Institution

Coll. of Eng., Design & Phys. Sci., Dept. of Electron. & Comput. Eng., Brunel Univ., Uxbridge, UK

Volume

7

Issue

4

fYear

2015

fDate

Aug. 2015

Firstpage

1

Lastpage

10

Abstract

Radio-over-fiber (RoF) systems comprise light modulation and transmission of millimeter-wave signals over fiber links. The aim of this study is to investigate the performance of external and direct intensity modulation in RoF links and to analyze the drawbacks induced by different components of the optical system. In external modulation, the Mach-Zehnder modulator (MZM) is used, whereas the vertical-cavity surface-emitting laser (VCSEL) is utilized in direct modulation. Both modulation schemes are tested for a vector modulation format, i.e., the quadrature amplitude modulation (QAM), where an orthogonal frequency-division multiplexing (OFDM) scheme is used to generate signal subcarriers. The simulations are carried out with the same values of common global parameters for both schemes of intensity modulation. Although VCSEL is a promising device for future RoF systems, the external modulation shows a more robust performance compared with that of VCSEL when implemented with the OFDM modulation technique.

Keywords

OFDM modulation; intensity modulation; laser cavity resonators; quadrature amplitude modulation; radio-over-fibre; surface emitting lasers; Mach-Zehnder modulator; OFDM RoF links; VCSEL; direct intensity modulation; external intensity modulation; orthogonal frequency-division multiplexing scheme; radio-over-fiber systems; vector modulation format; vertical-cavity surface-emitting laser; OFDM; Optical amplifiers; Optical fibers; Optical filters; Optical modulation; Optical receivers; Direct Intensity Modulation; External Intensity Modulation; Mach-Zehnder Modulator; Mach???Zehnder modulator (MZM); Optical OFDM; Radio-over-Fiber; Radio-over-fiber (RoF); Vertical-Cavity Surface-Emitting Laser; direct intensity modulation; external intensity modulation; optical orthogonal frequency-division multiplexing (OFDM); vertical-cavity surface-emitting laser (VCSEL);

fLanguage

English

Journal_Title

Photonics Journal, IEEE

Publisher

ieee

ISSN

1943-0655

Type

jour

DOI

10.1109/JPHOT.2015.2456499

Filename

7158985