How to Choose Fiber Optic Transceiver

Do you know the common IEEE descriptions like LX, SR and ZR? Many people are confused by the specification of the transceiver when choosing transceivers, thus making the transceiver selection painful. To make the right transceiver decision, you need take many parameters into consideration. This following paper is to introduce some important parameters frequently used in the selecting of the matching optical transceivers.

Transceiver Type

Before selecting transceiver, you’d better have a basic knowledge of transceiver types. Transceiver is a device with both a transmitter and a receiver which are combined and share common circuitry or a single housing. Typically, the fiber optic transceiver can be divided into different catalogs according to different standards. Usually, we can classify it by its package, transmission rate, and function (with or without hot pluggable). Among these classifications, the common one is divided by its package, thus we can get GBIC, SFP, SFP+, QSFP+, CFP, XFP, XENPAK and X2 and so on.

Protocol and Data Rate

In fiber optic technology, the protocol is the special set of rules used in transceiver application. Well, the data rate is usually measured by seconds in the transmission speed. Since different switch/router supports different protocol and data rate, you should make sure the protocol and data rate support your transceiver when selecting. The following are the most common protocol and data rate types.

Gigabit Ethernet: 1 GE/10 GE/40 GE/100 GE

Fiber Channel: 1 GFC (1.25 Gbps)/2 GFC/4 GFC/8 GFC/16 GFC

SDH STM-1 (155 Mbps)/STM-4 (622 Mbps)/STM-16 (2.5 Gbps/STM-64 (10 Gbps)

Multirate (155 Mbps to 2.67 Gbps)

CPRI up to 6 Gbps (for Video Transmission)

Transceiver Media

Transceiver can work over copper, single-mode fiber (SMF) and multi-mode fiber (MMF). In different Ethernet applications, media can achieve different link lengths when combined with transceivers. For example, the single-mode transceiver can reach a transmission distance of 5 km to 120 km, while multi-mode transceiver is defined to have the maximum reach of 550 m, with copper solution establishing even fewer link length at 25 m.

Power Budget

The power budget refers to the amount of loss that a data link (transmitter to receiver) can tolerate in order to operate properly. It has to be 2-3 dB larger than the measured link loss. Sometimes the power budget needs at least a minimum value of loss so that it does not overload the receiver and a maximum value of loss to ensure the receiver has sufficient signal to operate properly. As for the calculation of the link loss, transmission distance [km], number of ODFs, patches and passive optical components (Muxes) have to be considered. The following diagram describes how the power budget comes into being.

In conclusion, transceivers are devices widely used in optical communication network, such as metropolitan-area networks (MAN) and local area network (LAN). It is not easy to choose the right type of transceiver for your network, but above discussed parameters can guide you to transceiver selection.

Additional Information for common IEEE description:

Base -T: “copper” SFP with electrical RJ45 interface

SX: SFP 850 nm, MM, grey, 1GE, approx. 500 m

LX: SFP 1310 nm, SM, grey, 1GE, approx. 8 km

ZX: SFP 1550 nm, SM, grey, 1GE, approx. 70 km

CX4: “copper” XFP with electrical IB4x connector

SR: SFP+ or XFP 850 nm, MM, grey, 10GE, approx. 300 m

LR: SFP+ or XFP 1310 nm, SM, grey, 10GE, approx. 10 km

ER: SFP+ or XFP 1550 nm, SM, grey, 10GE, approx. 40 km

ZR: SFP+ or XFP 1550 nm, SM, grey, 10GE, approx. 80 km

SR4: QSFP 850 nm, MM, 40GE, approx. 100 m

SR10: CFP 850 nm, MM, 100GE, approx. 100 m

LR4: CFP or QSFP 1310 nm, SM, 40GE (CFP or QSFP) or 100GE, approx. 10 km

MM = multimode

SM = single mode