Optical Transceiver Module Tutorial From FiberStore

What is an Optical Transceiver module?

Optical Transceiver is a computer chip that uses fiber optic technology to communicate between other devices. This is opposed to a chip that transfers information electrically through metal wires and circuits or by the process of using various wave forms to communicate data. An optical transceiver chip is an integrated circuit (IC) that transmits and receives data using optical fiber rather than electrical wire.
Optical transceivers are typically used to create high bandwidth links between network switches. With the optical transceiver you can also create data transmission links capable of long range transmission.

Tips: Click here to know about the jargons related to fiber optic transceivers.


Development of Optical Transceiver Modules

Optical transceivers play an important role in conveying information across communication channels for Ethernet systems. They act as the all-in-one objects that receive and convey inforamtion, similar to those found in radios and telephone systems. With an optical transceiver, networks save much more space and avoid the need of having a transmitter and receiver apart inside a network. Capable of transmitting information further and faster than older models, the newer transceivers continue to change the way transceivers are used and appear, making for smaller, more compact modules than before. Here is a simple development of the transceivers.

Earliest Modules
SFP Module is one of the earliest transceiver devices which were created for Gigabit Ethernet networks and were preferred for their hot-swappable abilities. GBIC, or Gigabit interface Converters, allowed networks the ability to transmit data across copper or fiber-optic channels, creating a more versatile device than transmitters and receivers. Of course, GBIC modules were also have defect, and many had size and compatibility issues that limited their ability to transmit data across particular distances and at certain wavelengths.

XENPAK Modules
XENPAK became the new standard transceiver with increased support across longer distances and for multiple wavelengths. Unlike GBIC transceivers that sent information across either copper or fiber optic channels, XENPAKs included support for both networks, creating a better, more flexible module. And unlike the bigger GBIC transceivers, XENPAKs were capable of conveying data across short and long distances due to their configuration settings located inside the devices. When utilizing a single-mode configuration, networks create a single ray of light to send data across a long distance, while they use a multimode setup to transmit information across short distances. Both single and multimode fiber optics were utilized by networks, creating the XENPAK device ideal.

10 Gigabit Ethernet
X2 Transceiver and XPAK that the older XENPAK modules could no longer keep up with, were made when the 10 Gigabit Ethernet standard took hold. The smaller, more flexible X2 and XPAK standards allowed for even more support for the different Ethernet standards and were capable of transmitting data across longer distances.

And when the 10G SFP (SFP Plus or SFP+) came into existence, the competing standards of X2 and XPAK couldn't continue to control the market as they once had any more. SFP+ modules allowed for more configuration standards for networks, providing various wavelength and distance configurations for Ethernet.


Principle of Optical Transceiver Modules
Optical transceiver generally includes both a transmitter and a receiver in a single module. The transmitter and receiver are arranged in parallel so that they can operate independently of each other. Both the receiver and the transmitter have their own circuitry so that they can handle transmissions in both directions. The transmitter takes an electrical input and converts it to an optical output from a laser diode or LED. The light from the transmitter is coupled into the fiber with a connector and is transmitted through the fiber optic cable plant. The light from the end of the fiber is coupled to a receiver where a detector converts the light into an electrical signal which is then conditioned properly for use by the receiving equipment.

In a word, the optical transceiver module is the role of the photoelectric conversion. The transmitter converts electrical signals into light signals, and through the fiber optic transmission, the receiving end of the optical signals are converted into electric signals.


How Optical Transceivers Work In Personal Computers
When there is an issue, the pieces that make up the personal computers could be a mystery for many people. Without having an established understanding, we can feel helpless and incapable of fixing even the most basic of problems on ourself. So, it's necessary to make clear that how the transceivers work in the computers.
Considering that many of us are constantly on the internet, it may be easy to get an understanding of the most basic optical transceivers and how they make it so you can connect an search the internet with ease. To provide you with a straight connection to the web, you are either connected through a wireless network, or to an Ethernet cable which is connected to your modem or router when you are online. The Cat5 cable as it is also known, plugs into the computer by using the optical transceiver, which is often not housed on the side of your laptop, or the reverse end of the CPU.

There are many various modules that can be utilized as your optical transceiver. Unlike XFP modules, Cisco SFP modules, GigaBit interface converters, or GBIC modules, are some of your more average transceivers, and are input/output modules with one end that plugs into a gigabit ethernet port, while the opposing side is plugged into the fiber patch cables and links the fiber optic networks. Allowing the devices to process the data accordingly, the base function of the GBIC module is to communicate the signals between the Ethernet network and fiber optic network. One terrific aspect of the GBIC module is that it's a hot pluggable, allotting for a port to be changed from one kind of external interface to another by simply plugging the module in to an alternate external interface without having to power down the host switch or router in the process.


Application of Optical Transceiver Modules

Optical transceiver, essentially just completed the converted of data between different media, can realize the connection between two switches or computers in the 0-120km distance. Its main function is to achieve the conversion between optical-electrical and electrical-optical, including optical power control, modulation transmission, signal detection, IV conversion and limiting amplifier decision regeneration. In addition, there are security information query, TX-disable and other functions. Here is a summary in the practical application.

1. Optical transceivers can realize the interconnection between switches.

2. Optical transceivers can realize the interconnection between the switch and the computer.

3. Optical transceivers can realize the interconnection between computers.

4. Optical transceivers can act as the transmission repeater.
When the actual transfer distance exceeds the nominal transmission distance of the transceiver, in particular, the actual transfer distance exceeds 120km alerts, with 2 sets transceiver back to back in the case of on-site conditions allow, repeaters or the use of "optical-optical" conversiona relay, is a very cost-effective solution.

5. Optical transceivers can offer conversion between single-mode and multimode fiber connection.
When the networks appear to need a single multimode fiber connection, you can use a multimode transceiver and a single-mode transceiver back-to-back connections, which can solve the problem of single multimode fiber converted.

6. Optical transceivers can offer WDM transmission.
The lack of resources of long-distance fiber optic cable, in order to improve the utilization rate of the fiber optic cable, and reduce the cost, transceiver and wavelength division multiplexer (WDM multiplexer) with the use of two-way information on the same fiber transmission.


Classification of Optical Transceiver Modules
Optical Transceiver modules can be classified according to the following aspects.

1. Optical Fiber Type
Single-mode fiber transceiver and Multimode fiber transceiver. The single-mode version has a transmission distance of 20 to 120 km, while the multimode one's is 2 to 5 km. Due to the different transmission distance, the transceivers' transmit power, receiver sensitivity and the use of wavelength will be different.

2. Optical Fiber Count
Simplex fiber transceiver and Duplex fiber transceiver. The simplex version receives the data sent in a single fiber transmission, While the duplex one receives data transmitted on a dual fiber transmission. By definition, single fiber devices can save half of the fiber, a fiber that is in the receive and transmit data, where the fiber is very applicable to resource constraints. These products use the wavelength division multiplexing techniques, mostly using the wavelength 1310nm and 1550nm.

3. Transmission Rate
Transmission rate refers to the number of gigabits transmitted per second, per unit of Mbps or Gbps. Optical modules cover the following main rate: low rates, Fast, Gigabit, 1.25G, 2.5G, 4.25G, 4.9G, 6G, 8G, 10G and 40G.

4. Package
SFP, SFP+, GBIC, XFP, XENPAK, X2, 1X9, SFF, 200/3000pin, XPAK, etc. Click for Details About Related Packages.


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Optical Transceiver Modules

Optical transceiver module consists of optoelectronic devices, circuits and optical interface and other components. It can be divided into various kinds, respectively according to rates, applications, working modes and packages.
Rates: 100Base, 1000Base, 10GE in the application of Ethernet; 155M, 622M, 2.5G, and 10G in the application of SDH.

Applications: SDH/SONET, Ethernet, Fiber Channel, CWDM, DWDM etc..

Working Modes: Continuous and Burst (OLT/ONU).

Packages: 1 x 9, 2 x 9, SFF, SFP, GBIC, 300-PIN, XENPAK, X2，XFP, and SFP+, all kinds of packages are showing as below.

1 × 9 and 2 × 9 packages are welded type optical module, the general speed is less than 1000m, using SC interface.

SFF (Small Form Factor) is welded small package optical module, with the general speed of less than 1000Mbps and using LC interface. SFF small package optical module adopts advanced precision optics and integrated circuit process, size only ordinary duplex SC (1x9) half type optical fiber transceiver module. Optical port number in the same space can be increased one times, which can increase the line port density, reducing the system cost per port. And because the SFF small package module uses MT-RJ interface similar to the copper wire network, and the size of the common computer network wire interface is the same, it is conducive to the existing network devices in a copper based transition to optical fiber network high speed to meet the rapid growth of network bandwidth demand.

SFF transceiver modules are designed for a range of data rates up to 4 Gbps and offer physical compactness and pin-thru hole soldering onto a host board. They are available in several configurations including industry standard 2x5 / 2x10, and de-facto 2x7 pinout.

GBIC (giga bitrate interface converter) is hot pluggable Gigabit interface optical module, using SC interface. GBIC is the device that converts Gigabit electrical signal into optical signal interface. GBIC design can be used for hot plug. GBIC is an international standard interchangeable product. Switches with GBIC interface design are flexible and get a large market share in the market.

GBIC transceiver module is a hot-swappable input/output device that plugs into a Gigabit Ethernet port or slot, linking the port with the network by fiber optic cable or copper networking cable. It is an interface device used to convert Gigabit electrical signal to optical signal. By offering a standard, hot swappable electrical interface, one Gigabit port can support a wide range of physical media, from copper to long-wave single-mode optical fiber, at lengths of hundreds of kilometers.

SFP (small form factor pluggable) is a hot plug small package module, using the LC interface. SFP can be simply understood as an upgraded version of GBIC. Some switch manufacturers called SFP module for Mini GBIC. SFP module volume is reduced by half than the GBIC module, and can be set with double the number of ports in the same panel than GBIC. Other functions of SFP module are the same as GBIC.

SFP transceiver modules are hot-swappable in industry-standard cages and connectors, and offer high-speed performance in a compact package. SFP is used for data rates up to 4 Gbps and DWDM, including tunable versions. The electrical interface to the host board is a serial interface. Cisco GLC-T is one of the most popular SFP modules. Click to get Cisco GLC-T price.

300-PIN is a standardized MSA fiber pigtailed form factor for 10 and 40 Gbps fiber optic transponders used primarily in Telecom and DWDM applications. For 10 Gbps applications, SONET OC-192, SDH STM-64 and DWDM (including tunable) versions are available. For 40 Gbps applications, multiple standards are supported for 2km short reach optical links: SONET OC-768/SDH STM-256, 40GBASE-FR and OTU/OTU3e. For long-haul DWDM applications, OTU3 and OTU3e data rates are supported based on tunable advanced phase modulation formats.

XENPAK (10G Ethernet transceiver package) is a transponder used in Gigabit Ethernet, using the SC interface. It is a standardized form factor for 10 Gbps fiber optics transponders. XENPAK transponders are used in datacom optical links, primarily 10G Ethernet. The electrical interface to the host board is also standardized and is called XAUI (4 x 3.125 Gbps).

X2 (X-wavelength two ports) is a transponder used in Gigabit Ethernet, using the SC interface. It is a standardized form factor for 10 Gbps fiber optics transponders. X2 transponders are used in datacom optical links, primarily 10G Ethernet. The electrical interface to the host board is also standardized and is called XAUI (4 x 3.125 Gbps). X2-10G-LR modules are used very often in the fiber optic networks. X2 DWDM Cisco buy, plz come to FiberStore.

XFP (10 gigabit small form factor pluggable) is available in the 10G optical modules, Gigabit Ethernet, SONET and other system, using the LC interface. It is used for serial modules in 10GbE field, and is the optical module for next generation. XFP is a standardized form factor for serial 10 Gbps fiber optic transceivers. It is protocol-independent and fully compliant to the following standards: 10G Ethernet, 10G Fiber Channel, SONET OC-192, SDH STM-64 and OTN G.709, supporting bit rate from 9.95G through 11.3G. XFP transceiver modules are used in datacom and telecom optical links and offer a smaller footprint and lower power consumption than other 10 Gbps transponders. The electrical interface to the host board is a standardized serial 10 Gbps interface called XFI. Force10 XFP is one of the most popular XFP modules.

SFP+ (SFP plus) is the transceiver module that gigabit network used most commonly. It is used for 10Gbps Ethernet and 8.5Gbps system (Fiber Channel) with the new pluggable optical module size. SFP+ transceiver module has a shape more compact than the X2 and XFP packages, and its power consumption is less than 1W. In addition, it provides a installation density which is higher than the other 10G transceivers. SFP+ has the same volume as SFP industry standard due to a new design. SFP+ is a standardized form factor for fiber optic transceivers and is used in datacom and telecom optical links, offering a smaller footprint and lower power consumption than XFP transceivers. Initial standard applications focused on 8G Fiber Channel, 10G Ethernet and 10G Fiber Channel, where the electrical interface to the host board is a standardized serial interface called SFI. The applications have expanded to include SONET OC-192, SDH STM-64, OTN G.709, CPRI wireless, 16G Fiber Channel, and the emerging 32G Fiber Channel application. Click to buy CWDM 10Gig SFP+.

From 300-PIN to XENPAK, X2, and XFP, the 10G modules finally realizes the transmission of 10G signal with the same size as SFP, which is the SFP+ transceiver module. With the miniaturization, low cost and other advantages, SFP+ module meets the demand for high density optical modules. Since SFP+ standard was released in 2002, it has now replaced XFP and become the mainstream of 10G market.

The Evolution And Trends Of Fiber Optic Transceivers

When it comes to fiber optic transceivers, we can easily think of a lot of different package formats like 1X9, GBIC, SFF, SFP, etc.
1X9 package optical module was first produced in 1999, with SC head, is fixed optical module products, usually directly solidified on the circuit board of communication equipment, used as a fixed optical module. Then, 1X9 package optical module was gradually developed towards miniaturization and hot-pluggable.
Fiber optical module products began to develop in two aspects. One is hot-pluggable optical module, which became GBIC. The other is small, with LC head, directly solidified to the circuit board, which became SFF 2X5, or SFF 2X10.
Both GBIC and SFF optical modules have been widely used.
GBIC module, once widely used in switches, routers and other network products. The old Cisco and other vendors’ switched and routers have been widely adopted GBIC modules. Compared with 1X9, GBIC has obvious advantages, hot-pluggable feature makes GBIC can used as an independent module, users can easily maintain, update fiber optic transceivers and fault location. However, with the continuous development of network, GBIC module’s shortcomings also gradually appeared. The main disadvantage is its large size, resulting in a smaller density of service boards, boards can not accommodate a sufficient number of GBIC, unable to adapt to the trend of rapid development of network.
SFF module, is another branch of fiber optic modules’ evolution, now is widely used in EPON system. In the EPON ONU system, all adopt SFF module. The main reason why ONU use SFF optical module is EPON ONU products are usually placed in the users, require fixed rather than hot-pluggabe. With the rapid development of EPON technology, SFF market is gradually expanding.
SFP is the latest fiber optic transceiver, also is the most widely used module currently.
SFP module is hot-pluggabe (like GBIC) and small (like SFF). Using LC head, and its size is small as 1/2 to 1/3 as that of GBIC Module, which greatly increases the port density of network device, adaptable to the trend of the rapid development of the network, so it has been the most widely used. Currently the main equipment manufacturers, without exception, no one abandoned GBIC products and only produce SFP transceiver. Thanks to the centralized standards, SFP modules from different manufacturers can be compatible with each other, SFP is available as a stand-alone network equipment.
According to the rate, fiber optic transceivers can be divided into 100Base, 1000Base (Gigabit) and 10GE for Ethernet, 155M, 622M, 2.5G and 10G for SDH, which all have been widely used, and now the rate of 40G and 100G has appeared. The 10G modules are widely used in the main transmission, mainly include XENPAK, X2, XFP and 10G SFP+.
XENPAK module is an important step in the evolution. XENPAK in architecture for media access controller provides a XAUI interface. Serializer / deserializer to 10 Gbps available payload and forward error correction overhead assigned to the interface 4 channels, each one line signaling rate decreased to 3.125 Gbps. Compared with non-hot-pluggable, XENPAK module is very attractive, but it can not meet the demand of some important market. XENPAK power is typically 10W, caused a certain influence on the structure of size. Because it increases the printed circuit board manufacturing costs and reduce valuable trace space.
X2 transceiver also uses electrical interface(like XENPAK), but there are a few exceptions. X2 provides a 4-bit port address space, a bit less than XENPAK. X2 also reduces the number of power pins, and the bottom plate and electrical grounding utilities. X2 retained the 4 vendor-specific pin as Xenpak. In optical technology, X2 supports 10GbE, OC192 SONET, 10GFC and other standards.
XFP (10 Gb small form factor pluggable module), it provides a architecture with its four-channel interface different from XENPAK. XFP is a single-channel serial module using a XFI (10 Gb Serial Interface) connection at full speed, can replace XENPAK and its derived products. Without serializer / deserializer, XFP is smaller, cheaper and less power consumption.
SFP + module is smaller than XFP, the circuit for clock and data recovery is transferred to the card from the chip. SFP + module compressed size and power consumption through putting the CDR and electronic dispersion compensation outside the module.
No matter how fiber optical module develops, it has its own direction. Currently fiber optical transceiver mainly toward the directions of miniaturization, low cost, low power, high speed, long distance and hot pluggable.