The increasing demand for high-speed systems urges to design the system with low complexity and power consumption. In the current scenario, to achieve the technology demand of higher capacity at a lower cost the optical communication has been introduced. In optical communication, the transmission capacity is large along with the longer transmission distance [1–2, 7]. But in earlier decades, devices were implemented using semiconductor technology, where it has some limitations like high power dissipation, high input power, and low switching time [1, 4–6, 19]. To overcome the limitations of semiconductor technology, optical communication came into consideration. Optical communication is quite instrumental in the field of telecommunication due to its large bandwidth, high speed, and low interference [3, 6–9]. Due to these reasons, researchers have shifted focus on the optical signal to transmit the information [1, 5–7, 10–13]. Different types of optical techniques are employed such as metal-insulator-metal (MIM) [3–4, 28, 31, 33, 37, 43], insulator-metal-insulator (IMI) [28, 33], dielectric-loaded surface plasmon polaritons (DLSPP) [10–11, 21–22, 29, 31, 33, 35], metal slot waveguide [3–4]. The directional coupler already has been implemented by using a semiconductor optical amplifier (SOA) [15–16, 23, 27, 36–37] photonic crystal [13, 19, 31, 36–42, 44–45] and lithium niobate (LiNbO3) [5,8,15,]. SOA have some limitations like gain saturation and high driving current input and in LiNbO3 the electrical signal is used to switch the optical signal. The current work purposes the optimization of the area in the directional coupler structure. Surface plasmon polaritons (SPPs) [10–11, 18, 21–22, 29, 31, 33, 35] are the electromagnetic waves that travel along a metal-dielectric or metal-air interface and SPPs are excited by both electrons and photons. Plasmonic is considered as a potential solution for size and operating speed mismatch problems in electronics and photonics [3–4, 6]. The motivation behind plasmonic is the ability the realization of very compact photonic devices [13, 31]. To obtain a satisfactory performance between loss and confinement, MIM [3–4, 6, 28, 31, 33, 37, 43] has been preferred due to the ability to confine surface plasmon diffraction limit . The important structure in optical communication is directional coupler [3–4, 9, 14, 19, 28–30, 32–34] and it can be implemented in various applications like power splitter , optical switches, and wavelength selective coupler, etc. . In this paper, the structure of the optimized 10-dB and 3-dB directional coupler is proposed. The compact design of the directional coupler is proposed in the footprint of 8 μm x 4μm. The proposed design is verified using FDTD [1, 3, 7, 14, 21, 31–32, 36, 39–40, 42] method. In this paper, the optimized design of 10-dB and 3-dB directional coupler is discussed in Sect. 2, and in Sect. 3 simulation resultsand discussions are presented. Finally, the conclusion of the paper has been deliberated.