It’s no mystery why fiber optic technology has grown in popularity since it was commercially introduced in the 1970s. Sending data via infrared light pulses on a fiber line, rather than electrically over copper cable, allows the transmitting of more information faster, over longer distances and with no threat of radio or electromagnetic interference. That’s why it is often the choice for systems that demand high bandwidth over long distances, as well as short distances with large bandwidth requirements such as data centers.
But not everybody understands the crucial component onto and off the fiber optic superhighway – the fiber optic transceiver.
A fiber optic (or optical) transceiver serves as both a transmitter and a receiver. It is a small component that is plugged or embedded into another device within a data network like a switch or a router. At the on ramp, it converts an electrical signal from the switch or router to an optical (light) signal. At the off ramp, it converts the optical signal back to an electrical signal.
This blog explains the main terms you will encounter while shopping L-com’s selection of over a thousand optical transceivers.
Form Factors
A form factor indicates a transceiver’s shape and size. So that transceivers from different vendors are compatible, most manufacturers design them based on the same set of standards, known as the Multisource Agreement (MSA). We recommend you use transceivers that are MSA compliant.
Some common form factors include GBIC, SFP, SFP+ and XFP. Which type you should use depends on the speed, throughput and distance you need to achieve.
Though many GBIC and SFP transceivers perform equally, SFPs are generally considered an upgrade. The SFP’s design is based on the older GBIC design but is smaller and allows the placement of more transceivers per inch on a motherboard. Ideal for data communications and telecommunications, the SFP is available in versions that support both multimode fiber and single-mode fiber. In single mode it operates at wavelengths of 1310 nm and 1550 nm and over distances of 2 km to 120 km. In multimode it handles 850 nm at up to 500 meters. (Fiber modes and wavelengths are explained below.)
The SFP+ is an improvement on the SFP, though they are the same size. The SFP performs at data rates up to 4.25 Gb/s, while SFP+ offers 8.5 Gb/s to 16 Gb/s. The XFP form factor is capable of more than 10 Gb/s, though it is about 30% larger than SFP and SFP+ transceivers and uses more energy. The XFP can reach up to 100 km over single-mode fiber.
Connectors
An optical transceiver’s “connector type” refers to its interface for accommodating a fiber cable. Common connector types are LC, SC, ST, MT-RJ and MPO. Particularly prevalent are LC and SC. LC fiber connectors are typically found on SFP, SFP+, XFP, QSFP and SFF transceivers. SC fiber connectors are typically found on GBIC, BiDi SFP, X2, XENPAK and 1×9 transceivers. LC connectors have a latch to provide stability. SC connectors are nonlatching and therefore ideal for quick patching of cables. L-com also offers transceivers with pluggable RJ-45 connectors for compatibility with copper networks.
Wavelengths
Wavelength is the optical term for frequency. When a transceiver converts an electrical signal into a light signal, each data stream is changed to a signal on its own wavelength, which is measured in nanometers (nm). Three central wavelengths are most used in fiber optics: 850 nm, 1310 nm and 1550 nm. The longer the wave, the less loss of signal strength during transmission. Therefore, 850 nm is used for shorter runs of fiber links and 1550 nm for longer runs.
Transmission Rates
A fiber optic transceiver’s transmission rate, or data rate, refers to the number of bits it transmits, expressed in either megabits per second (Mbps) or gigabits per second (Gbps). A transceiver is classified into one of over two dozen transmission rates, from 0.5 Mbps up to 20 Gbps.
Distance Range
The transmission distance of an optical transceiver is the maximum distance it can transmit an optical signal. The distance is usually expressed in meters or kilometers. L-com’s full line of transceivers covers about a dozen distance ranges, from 30 meters up to 120 km.
Fiber Modes: MMF vs. SMF
An optical transceiver mates with either multimode fiber (MMF) or single-mode fiber (SMF). Besides being able to transport light in multiple modes, MMF has a larger core diameter and works in the 850 nm and 1310 nm wavelengths. It is used for shorter distances and lower-speed networks like LANs. SMF transmits only one mode at a time, has a smaller core and can handle the longer 1550 nm wavelength. Because it is more highly focused, with less light dispersion, SMF can handle longer distances, typically from 10 km to 160 km.
Platforms
Each transceiver is made to be compatible with one of the many switch and router platforms that are in use. L-com offers models that meet the specifications of more than 40 platforms. We have particularly large selections for popular platforms such as MSA, Cisco, Ciena, Alcatel 7x50, Adva, Cyan, Cisco ONS, Elkinops, Arris and BTI.
Summary
Fiber optic transceivers are essential to converting electrical signals to optical signals and vice versa. When shopping for them, it helps to understand several terms. The form factor you choose will depend on the type of data converted, the speed and distance required andthe equipment you plug them into. The appropriate connector will depend on the form factor. Transceivers accommodate different wavelengths, with the longer the wavelength, the less amount of signal loss. A transceiver’s transmission rate is the number of bits it can send per second. And finally, a transceiver operates in modes, with either multimode fiber at shorter distances or single-mode fiber at longer distances.
L-com offers fiber optic transceivers that are MSA-compliant, are compatible with 40+ switch and router platforms, and are available in the form factors you use. Need help deciding on the fiber transceiver for you? See our Fiber Optic Solutions brochure or connect with one of our L-com technical experts now. Call us toll-free at 1-866-506-2818, chat with us live, or email us at sales@l-com.com.
