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We have investigated the theoretical and principal analysis of cascaded electroabsorption modulators (EAMs) and Mach-Zehnder modulator (MZM). We have proposed a technique to generate an ultraflat and power efficient optical frequency comb (OFC) by the serial cascading of two EAMs and one single-drive MZM. Continuous wave (CW) light source is modulated and spectrum broadened by two EAMs and MZM, respectively. Here, EAMs in cascaded mode produce ultrashort pulses followed by MZM, which is introduced to perform intensity modulation and tuned the power variation of even and odd order sidebands at the same level for obtaining a flat optical spectrum at the output. The first EAM acts as a subcarrier generator and the latter one acts as a subcarrier enhancer, which is followed by the MZM acting as subcarrier flatter. By this proposed technique, we have generated 63 subcarriers with 10-GHz spacing and within 2-dB power fluctuation. The generated OFC has a bandwidth of 630 GHz. This technique generates OFC with an appreciable power level and flattened optical spectrum, which is very much essential in dense wavelength division multiplexing and elastic optical networks. [ABSTRACT FROM AUTHOR]

Traditional dense wavelength division multiplexing (DWDM) technology is no longer enough to meet the extensive growth in the demand of bandwidth in an efficient and effective manner under the fixed grid environment. Thus, a technology is needed to overcome the challenges raised by the ever-increasing demand of bandwidth in an effective manner with efficient utilization of spectral resources. To solve this problem, an elastic optical network (EON) paradigm comes into existence. It uses a flexible grid technology that removes the limitations of fixed grid DWDM technology and increases the channel capacity to meet current bandwidth demand with proper utilization of optical spectrum. We present the evolution of EON from the DWDM network. We have discussed the main components and characteristics of EON that includes superchannel and sliceable bandwidth variable transponder (SBVT). Thereafter, we discuss the different modulation and transmission techniques used in EON. Next, we present the recently proposed architectures of SBVT followed by its applications. Lastly, we have discussed various subcarrier generation techniques in brief. [ABSTRACT FROM AUTHOR]