ehnder modulators (MZM) are used for high bit rates. For modulation of the optical signal, Si PN junction-based phase shifters are used. In MZM for coupling of the optical signal, two Si grating couplers, which operate in C-band, are used [26-29]. 10.3.3 OPTICAL AMPLIFIER Erbium-doped fiber amplifiers are not compatible with photonic integrated circuits because in outdoor equipment, power consumption is critical. To reduce the size, provide low power consumption and low loss, SOA integrated with a silicon photonic circuit is used. By using an integrated amplifier, zero loss equipment can be designed. Heterogeneous III-V/Si semiconductor optical amplifiers are used to overcome the loss at the transmitter and to amplify optical power at the receivers of the optical transceivers. At various wavelengths and input powers, the gain of the amplifier obtained [26-29]. 10.3.4 PASSIVE OPTICAL DEVICES, SWITCHES, AND MULTIPLEXERS Passive optical devices are used for low cost, to simplify network operation, and to reduce equipment inventory. These filters are used in wavelength selective passive optical networks and broadcast-and select optical add-drop multiplexers. The reconfigurable optical add-drop multiplexer (ROADM) provides flexibility in decreasing inventory cost, and network up-gradation, and enables software reconfig- uration. ROADM can support 20 channels at the 100 Gbps bit rate and has less power requirement for wavelength selection. Tunable photonics components such as filters, switches, and lasers can be implemented with the help of silicon photonics. Wavelength filters, switches, and modulators are designed by the thermo optic electro-optic effect in MZI and ring resonators. Ring resonator based switching devices are designed for centralized access networks and are a prototype of the Mini-ROADM. The mini-ROADM device is polarization independent. To obtain polarization independence, a polarization diver- sity structure is used which consists of ring resonator-based switching elements. 5G Wireless Communication 