Optik 124 (2013) 5139–5141 Contents lists available at ScienceDirect Optik jou rn al homepage: www.elsevier.de/ijleo Analysis of multitone microwave signals on optical ﬁber system using external laser modulation Parveen Rani a,∗ , Kamaljit Singh Bhatia b , Kulwinder Singh c a Department of Electronics and communication, Bhai Maha Singh College of Engg., Sri Muktsar Sahib, 152026, India b Department of Electronics and Instrumentation, Sri Guru Granth Sahib World University, Fatehgarh Sahib, India c Department of Electronics and communication, Bhai Maha Singh College of Engg, Sri Muktsar Sahib, 152026, India a r t i c l e i n f o Article history: Received 8 October 2012 Accepted 11 March 2013 Keywords: External modulator Multitone optical Fiber (MoF) system Optical signal to noise ratio (OSNR) a b s t r a c t In this paper, we Analyze multitone microwave signals on optical ﬁber with different tone signals and utilizing various possibilities of regeneration and ampliﬁcation by different means. We compare out the performance analysis of Erbium doped ﬁber ampliﬁers (EDFAs) and Semi-conductor Optical Ampli- ﬁers (SOA). One tone’s frequency varies from 1 to 20 GHz through parametric runs and other has ﬁxed frequency of 5 GHz and third harmonic tones may be monitored. © 2013 Published by Elsevier GmbH. 1. Introduction Microwave-over-ﬁber technologies are of great interest for many potential applications such as broad-band wireless access networks, sensor networks, radar and satellite communication sys- tems, and have been extensively studied in the last few years. The key function of a microwave-over-ﬁber network is to distribute microwave and millimeter-wave signals over optical ﬁber to take the advantages of the low loss, low dispersion, and large band- width of optical ﬁber links [1]. Many papers have been published in the last decades for optical microwave over ﬁber for excitation of multi tones [2–5]. However, to the best of our knowledge, no approaches have been proposed to analyze multitone microwave using external modulator over a ﬁber link. Direct modulation of semiconductor lasers at high data rate is attractive more for analysis of multitones. it offers advantages of simplicity, no excess insertion loss from modulator, and potentially low cost [6]. But a 10-Gb/s directly modulated distributed feedback laser diode (DFB-LD) may be deployed in access networks due to the shorter span lengths [7]. In this Paper, we propose an approach to perform analysis of multitones using external modulator in a microwave-over- ﬁber link. In MoF system we investigates the performance of external modulator combining with performance of two different optical ampliﬁers named as EDFA(erbium doped ﬁber ampliﬁer) and SOA(semiconductor optical ampliﬁer). An erbium doped ﬁber ∗ Corresponding author. E-mail address: sawneparveen@gmail.com (P. Rani). ampliﬁer (EDFA) consists of a few meters of optical ﬁber doped with a few parts per million of the rare earth element erbium. The optical signal is injected into this ﬁber, along with the light from a special “pump” laser that is designed to excite the erbium ions [8] and In SOA ampliﬁer, The ampliﬁcation function is achieved by externally pumping the energy levels of the material. 2. Operation principle In multitone MOF system we are using optsim simulator for analyzing the multitones. The concept of analyzing microwave multitone signals is a simple process which is carried out simply comparing two different tones. One is having varying frequency and other has constant. This process can be achieved by using the simple ﬁber-based system shown in Fig. 1. In multitone MOF system, two modulating tones are employed. The frequency of one tone is varied from 1 to 20 GHz, while the other one is ﬁxed at 5 GHz Fig. 1 shows the multitone MOF system in which EDFA ampliﬁer is used with photodetector for the detection of microwave signals. Microwave signal is transmitted through the ﬁber. Due to long distance traveling of signal, EDFA or SOA ampliﬁer at end of the channel is used to maintain the signal strength and help in the detection of the signal [9]. Display device is used to give the results. In this system external laser modulation is obtained at the transmitter by photodiode and optical modulator. On the other hand, analysis of multitone over MoF system can also be done by direct laser modulation. Direct modulation is directly obtained from the optical modulator but this modulation is less effective than the external laser modulation. So we are, here concentrate only on external modulation in multitone MoF system. Basically 0030-4026/$ – see front matter © 2013 Published by Elsevier GmbH. http://dx.doi.org/10.1016/j.ijleo.2013.03.074