RESEARCH ARTICLE Performance evaluation of hybrid optical ampliﬁers in WDM system Deepak Malik 1 • Geeta Kaushik 2 • Amit Wason 3 Received: 11 September 2017 / Accepted: 29 May 2018 Ó The Optical Society of India 2018 Abstract There is a huge demand of bandwidth and gain in today’s high tech era. To fulﬁl this demand proper ampliﬁcation is required. Hybrid Optical Ampliﬁer made a remarkable change in present optical networks in order to amplify the signals for better performance of a system. In this paper, we have proposed the different conﬁgurations of hybrid optical ampliﬁers for better performance of Wave- length Division Multiplexed (WDM) systems. This paper also provides a crucial insight into the performance of different conﬁgurations of hybrid optical ampliﬁers (such as EDFA–Raman, EDFA–EDFA and SOA–EDFA) at 10 Gbps in WDM systems with 0.4 and 0.8 nm channel spacing. Work capacities of the systems were compared on the basis of various parameters viz., ﬁber length, disper- sion, bit error rate, quality factor, eye diagram and output power. Attempts were taken to design 8 9 10 Gbps Dense Wavelength Division Multiplexed system with reduced channel spacing and 16 9 10 Gbps WDM system with 100 GHz channel spacing. It was assessed that for WDM system with 16 inputs and channel spacing of 0.8 nm, Raman–EDFA conﬁguration gives better results as com- pared to EDFA–EDFA and SOA–EDFA conﬁgurations. Further, it was observed that SOA–EDFA conﬁguration with reduced channel spacing (0.4 nm) provided maximum output power and better eye opening with lowest BER at a distance of 100 km. Moreover, it was seen that with increase in channel dispersion from 2 to 8 ps/nm/km, the quality of the signal started decreasing. Keywords BER Á Hybrid optical ampliﬁer Á Output power Á Quality factor Introduction The Dense Wavelength Division Multiplexed (DWDM) with high ﬂexibility, transparency and reliability has become the preferred technique these days to cover the longer distances along with large number of channels [1, 2]. Using this technology number of channels can be increased on demand. Conventional ampliﬁers such as Raman ampliﬁer, Erbium Doped Fiber Ampliﬁer (EDFA) and Semiconductor Optical Ampliﬁer (SOA) are the major components of WDM optical networks [3, 4]. Among the above-mentioned ampliﬁers, Raman optical ampliﬁer has grabbed huge attention due to its transparency to amplify any wavelength by adjusting pump wavelength [5]. Addi- tionally, Raman ampliﬁer reduces the non-linearity by improving overall performance of the system [6]. On the other hand, EDFA was used for long distance transmission due to its high on–off ratio. Simultaneously, it can also amplify large number of signals of different wavelengths. Singh and Kaler [7] reported a 20 9 10 Gbps WDM transmission system using cascaded inline semiconductor optical ampliﬁer by using 100 GHz channel spacing with OOK and DPSK modulation formats. It was found that DPSK system performs best for 1190 km transmission distance with bit error rate observed \ 10 -10 and quality factor of 15 dB for all channels. In comparison with Raman ampliﬁer and EDFA, SOA is low cost, requires less power and has wide spectrum ampliﬁcation that can amplify all & Amit Wason wasonamit13@gmail.com 1 MMEC, MMU, Mullana, Ambala, India 2 ECE Department, MMEC, MMU, Mullana, Ambala, India 3 Ambala College of Engineering and Applied Research, Devsthali, Ambala, India 123 J Opt https://doi.org/10.1007/s12596-018-0470-1