Optical networks utilize several key protocols to manage data transmission, including Synchronous Optical Networking (SONET), Synchronous Digital Hierarchy (SDH), and Optical Transport Network (OTN). These protocols ensure efficient, reliable, and scalable data transport over optical fibers. Additionally, Wavelength Division Multiplexing (WDM) and its dense variant (DWDM) are used to increase the capacity of optical fibers by transmitting multiple data channels on different wavelengths of light.