is probably the most diffused transceiver format available with a variety of differ- ent transmitter and receiver types, allowing users to select the appropriate transceiver for each link to provide the required optical reach over the available optical fiber (e.g., multi- mode fiber or single-mode fiber). Technology for Telecommunications: Integrated Optics and Microelectronics 13.4 mm Label 8.5 mm 55 mm Dustplug Receiver optical bore Transmitter optical bore Bail clasp FIGURE 5.82 Pictorial representation and dimensions of a pluggable SFP transceiver. A drawing of an SFP transceiver is presented in Figure 5.82, where the particular con- nector for the input and output fibers that, with different dimensions, is present in all the transceivers is evidenced. The way in which the SFP transceivers are hosted on the motherboard using a suitable cage allowing a hot plug is shown in Figure 5.83, where both the empty cages on the front of a system card and the cages with plugged SFPs are shown. Optical SFP modules are commonly available in four different categories: 850 nm (SX), 1310 mm (LX), 1550nm (ZX), and WDM, both DWDM and CWDM. SFP transceivers are also available with a "copper" cable interface, allowing a host device designed primarily for optical fiber communications to also communicate over unshielded twisted pair net- working cable. Commercially available transceivers have a capability up to 2.5 Gbit/s for transmission applications; moreover, a version of the standard with a bit rate of 10 Gbit/s exists, but it can be used only to connect nearby equipment, and is very useful to spare space and power consumption as interface in the client cards of line equipments. Modern optical SFP transceivers support digital optical monitoring functions accord- ing to the industry standard SFF-8472 MSA. This feature gives the end user the ability to monitor real-time parameters of the SFP, such as optical output power, optical input power, temperature, laser bias current, and transceiver supply voltage. SFP transceivers are d