This passage is a basic knowledge of fiber optic communication systems aim to help you have a quick learning of the products. It is suitable for beginners,. If you are engineers or if you already are familiar with the products and systems you can skip it.
What is Fiber Optical Transceiver?
Optical transceiver is also called fiber optic transceiver, optical module, transceiver module or switch module, which is a device that has both a transmitter and a receiver. The optical transceiver can transfers information electrically to various fibre wave forms to communicate data. 
The common optical transceivers include 1X9, SFP, GBIC,SFF, XFP, XENPAK,X2 and XPAK, datarates covers OC-3/STM-1,OC-12/STM-4,OC-48/STM-16, OC-192/STM-64,1.25Gb/s, 2.125Gb/s, 4.25Gb/s, 8.5Gb/s, 40Gb/s, 100Gb/s. They can used in Fast ethernet, Gigabit Ethernet, 10 Gigabit Ethernet ( 10GE or 10GbE or 10 GigE), SDH, SONET, Fibre channel, local area network(LAN), Wide area network(WAN),Storage area network (SAN), Metro Area Network and so on.
What is SFP ?
The small form-factor pluggable (SFP) or Mini-GBIC is a compact, hot-pluggable optical transceiver used for both telecommunication and data communications applications. It's also called SFP module, SFPs and SFP's. It interfaces a network device mother board (for a switch, router, media converter or similar device) to a fiber optic or copper networking cable. It is a popular industry format supported by many network component vendors.SFP transceivers are designed to support SONET, Gigabit Ethernet, Fibre Channel, and other communications standards.
SFP transceivers (SFP Module) are available with a variety of types, SFP transceivers (SFP modules) are commonly available in several different categories:
850nm 550m multi-mode fiber (SX)
1310nm 10km single-mode fiber (LX)
1490nm 10km single-mode fiber (BS-D)
1550nm 40km (XD), 80 km (ZX), 120 km (EX or EZX)
1490nm 1310nm (BX), Single Fiber Bi-Directional Gigabit SFP Transceivers
Copper SFP with RJ45 connector
Single-fiber BIDI SFPs.
The SFP transceiver is specified by a multi-source agreement (MSA) between competing manufacturers. The SFP was designed after the GBIC interface, and allows greater port density (number of transceivers per cm along the edge of a mother board) than the GBIC, which is why SFP is also known as mini-GBIC. The related Small Form Factor transceiver is similar in size to the SFP, but is soldered to the host board as a pin through-hole device, rather than plugged into an edge-card socket.
However, as a practical matter, some networking equipment manufacturers engage in vendor lock-in practices whereby they deliberately break compatibility with "generic" SFPs by adding a check in the device's firmware that will only enable the vendor's own modules, Such as Allied Telesis, AVAYA, Brocade, Cisco, DELL, D-LINK, Emulex, Enterasys, Foundry, HP, Huawei, H3C, Juniper, Linksys, Netgear, Nortel, Planet,Trendnet, ZyXEL, ZTE, SMC and 3com.
For more information, please refer to
What is GBIC?

GBIC stands for Gigabit Interface Converter. A GBIC or GBICs or GBIC's is a type of Optical Transceiver. It is an module which converts serial electric signals into serial optical signals and vice versa. In the Optical Networking world, a GBIC is commonly used to interface a Fiber Optic system with an Ethernet system. Common applications include Fibre Channel and Gigabit Ethernet. The GBIC form factor allows manufacturers to design one type (form factor) of device which can be used for either copper or optical applications. GBIC modules are hot swappable, which increases the ease of upgrading Optical networks. The GBIC has become a standard form factor for optical transceivers, and can support a variety of physical media, from legacy copper to long wave single mode fiber up to lengths of hundreds of kilometers.


The GBIC is an appealing standard in networking equipment because of its flexibility. In networks where a variety of different optical technologies are deployed, IT staff can purchase GBIC modules as needed, for the specific type of link needed. The flexibility of the GBIC standard drives costs down and gives IT administrators far more flexibility. The GBIC standard is non proprietary and is defined by the SFF Committee in document SFF-8053i. A variation of the GBIC called the mini-GBIC or SFP exists as well. It has the same functionality / modularity but in a smaller form factor.

For more information, please refer to http://en.wikipedia.org/wiki/Gigabit_interface_converter

What is X2 transceiver?
An X2 Transceiver is a 10G fiber optic transceiver based on former Xenpak transceiver standards. The functionality of X2 and Xenpak transceivers is nearly identical, but an X2 Transceiver can also use one transceiver to fulfill all 10G Ethernet optical port functions. Physically, an X2 Transceiver is approximately 50% smaller than an equivalent Xenpak transceiver, which often makes the X2 a better choice for higher density applications. All X2 Transceivers carried by Optcore conform to the IEEE 10Gbps Ethernet standard. All of our Cisco Compatible, 3rd party X2 transceiver products are also Multi Source Agreement (MSA) compliant, and will not void OEM warranty. The 10Gbps Ethernet standard is defined by the IEEE, and not only increases the data transmission rate, but also increases transmission distance over previous transceiver types. The IEEE 802.3ae 10G Ethernet standard defined the working distance from 300 meters to 40km. Optcore offers a variety of X2/Xenpak fiber optic transceivers that are fully compatible with Cisco, 3Com, HP, D-Link, Juniper and so on.


What is Medium Attachment Unit
A Medium Attachment Unit (MAU) is a transceiver which converts signals on an Ethernet cable to and from Attachment Unit Interface (AUI) signals. On original 10BASE5 (Thick) Ethernet, the MAU was typically clamped to the Ethernet cable. With later standards it was generally integrated into the network interface controller and eventually the entire Ethernet controller was often integrated into a single integrated circuit ("chip") to reduce cost.


In most modern switched or hubbed Ethernet over twisted pair systems, neither the MAU nor the AUI interfaces exist (apart, perhaps as notional entities for the purposes of thinking about layering the interface), and the category 5 (CAT5) cable connects directly into an Ethernet socket on the host or router. For backwards compatibility with equipment which still has external AUI interfaces, MAUs are still available with 10BASE2 or 10BASET connections.


However, the tradition of using a separate low-level I/O device in networking has continued in fast optical fiber network interfaces, where the GBIC, XENPAK, XFP, and enhanced small form-factor pluggable (SFP+) pluggable transceiver modules using the XAUI interface play a similar role.

What is XFP?
The XFP (10 Gigabit Small Form Factor Pluggable) is a standard for transceivers for high-speed computer network and telecommunication links that use optical fiber. It was defined by an industry group in 2002, along with its interface to other electrical components which is called XFI.
XFP modules are hot-swappable and protocol-independent. They typically operate at optical wavelengths (colors) of 850 nm, 1310 nm or 1550 nm. Principal applications include 10 Gigabit Ethernet, 10 Gbit/s Fibre Channel, Synchronous optical networking (SONET) at OC-192 rates, Synchronous optical networking STM-64, 10 Gbit/s Optical Transport Network (OTN) OTU-2, and parallel optics links. They can operate over a single wavelength or use DWDM techniques. They include digital diagnostics that provide management that were added to the SFF-8472 standard. XFP modules use an LC fiber connector type to achieve high density.
For more information, please refer to http://en.wikipedia.org/wiki/XFP_transceiver
What is SFP+ (SFP plus)?
SFP+ Stands for Enhanced small form-factor pluggable transceiver, it is an enhanced version of the small form-factor pluggable transceiver, commonly known as SFP. It supports data rates up to 10 Gbit/s. SFP+ supports 8 Gbit/s Fibre Channel, 10 Gigabit Ethernet and Optical Transport Network standard OTU2. It is a popular industry format supported by many network component vendors.
In comparison to earlier XENPAK or XFP modules, SFP+ modules leave more circuitry to be implemented on the host board instead of inside the module. Consideration has to be given to whether the module is linear or limiting. Linear SFP+ modules are appropriate for 10GBASE-LRM otherwise limiting modules are preferred.
What is SFP plus direct attach?
Also known as 10GSFP+Cu, 10GBase-CR, or 10GBase-CX1, this uses a passive twin-ax cable assembly and connects directly into an SFP+ housing. It has a range of 10 m and like 10GBASE-CX4, is low power, low cost and low latency with the added advantage of having the small form factor of SFP+. SFP+ Direct Attach is expected to be the optimum solution for reaches of 10 m.
What is Fiber media converter?
Fiber media converters are simple networking devices that make it possible to connect two dissimilar media types such as twisted pair with fiber optic cabling. They are important in interconnecting fiber optic cabling-based systems with existing copper-based, structured cabling systems. They are also used in MAN access and data transport services to enterprise customers.
Fiber media converters support many different data communication protocols including Ethernet, Fast Ethernet, Gigabit Ethernet, T1/E1/J1, DS3/E3, as well as multiple cabling types such as coax, twisted pair, multi-mode and single-mode fiber optics. Media converter types range from small standalone devices and PC card converters to high port-density chassis systems that offer many advanced features for network management.
Fiber media converters can connect different Local area network (LAN) media, modifying duplex and speed settings. Switching media converters can connect legacy 10BASE-T network segments to more recent 100BASE-TX or 100BASE-FX Fast Ethernet infrastructure. For example, existing Half-Duplex hubs can be connected to 100BASE-TX Fast Ethernet network segments over 100BASE-FX fiber.
When expanding the reach of the LAN to span multiple locations, media converters are useful in connecting multiple LANs to form one large campus area network that spans over a limited geographic area. As premises networks are primarily copper-based, media converters can extend the reach of the LAN over single-mode fiber up to 130 kilometers with 1550 nm optics. Wavelength-division multiplexing (WDM) technology in the LAN is especially beneficial in situations where fiber is in limited supply or expensive to provision. As well as conventional dual strand fiber converters, with separate receive and transmit ports, there are also single strand fiber converters, which can extend full-duplex data transmission up to 70 kilometers over one optical fiber. Other benefits of media conversion include providing a gradual migration path from copper to fiber. Fiber connections can reduce electromagnetic interference. Also fiber media converters pose as a cheap solution for those who want to buy switches for use with fiber but do not have the funds to afford them , they can buy ordinary switches and use fiber media converters to use with their fiber network.
What is 10 Gigabit Ethernet?
The 10 gigabit Ethernet (10GE or 10GbE or 10 GigE) computer networking standard defines a version of Ethernet with a nominal data rate of 10 Gbit/s (billion bits per second), ten times as fast as gigabit Ethernet.10 gigabit Ethernet defines only full duplex links which are generally connected by network switches. Half duplex operation and CSMA/CD (carrier sense multiple access with collision detection) do not exist in 10GbE.
What is 10GBASE-SR?
10GBASE-SR ("short range") uses the IEEE 802.3 Clause 49 64B/66B Physical Coding Sublayer (PCS) and 850 nm lasers. It delivers serialized data over multi-mode fiber at a line rate of 10.3125 Gbit/s.
Over obsolete 62.5 micron multi-mode fiber cabling (OM1), it has a maximum range of 26–82 metres (85–269 ft), depending on cable type. Over standard 50 μm 2000 MHz·km OM3 multi-mode fiber (MMF), it has a maximum range of 300 metres (980 ft). The transmitter can be implemented with a vertical-cavity surface-emitting laser (VCSEL) which is low cost and low power. MMF has the advantage of having lower cost connectors than SMF because of its wider core.
What is 10GBASE-LR?
10GBASE-LR ("long reach") uses the IEEE 802.3 Clause 49 64B/66B Physical Coding Sublayer (PCS) and 1310 nm lasers. It delivers serialized data over single-mode fiber at a line rate of 10.3125 Gbit/s.10GBASE-LR has a specified reach of 10 kilometres (6.2 mi), but 10GBASE-LR optical modules can often manage distances of up to 25 kilometres (16 mi) with no data loss.
Fabry–Pérot lasers are commonly used in 10GBASE-LR optical modules. Fabry–Pérot lasers are more expensive than VCSELs but their high power and longer wavelength allow efficient coupling into the small core of single mode fiber over greater distances.
What is 10GBASE-LRM?
10GBASE-LRM, (Long Reach Multimode) also known as 802.3aq uses the IEEE 802.3 Clause 49 64B/66B Physical Coding Sublayer (PCS) and 1310 nm lasers. It delivers serialized data over multi-mode fiber at a line rate of 10.3125 Gbit/s.10GBASE-LRM supports distances up to 220 metres (720 ft) on FDDI-grade 62.5 µm multi-mode fibre originally installed in the early 1990s for FDDI and 100BaseFX networks and 260 metres (850 ft) on OM3. 10GBASE-LRM reach is not quite as far as the older 10GBASE-LX4 standard. However it is hoped that 10GBASE-LRM modules will be lower cost and lower power; and because 10GBASE-LRM uses the same PCS as XFI and SFI no recoding of data is required with the XFP and SFP+ module MSAs.
What is 10GBASE-ER?
10GBASE-ER ("extended reach") uses the IEEE 802.3 Clause 49 64B/66B Physical Coding Sublayer (PCS) and 1550 nm lasers. It delivers serialized data over single-mode fiber at a line rate of 10.3125 Gbit/s.10GBASE-ER has a reach of 40 kilometres.
What is 10GBASE-ZR?
Several manufacturers have introduced 80 km (50 mi) range ER pluggable interfaces under the name 10GBASE-ZR. This 80 km PHY is not specified within the IEEE 802.3ae standard and manufacturers have created their own specifications based upon the 80 km PHY described in the OC-192/STM-64 SDH/SONET specifications.
What is 10GBASE-LX4?
10GBASE-LX4 uses the IEEE 802.3 Clause 48 Physical Coding Sublayer (PCS) and coarse WDM. It supports ranges of between 240 metres (790 ft) and 300 metres (980 ft) over legacy multi-mode cabling. This is achieved through the use of four separate laser sources operating at 3.125 Gbit/s in the range of 1300 nm on unique wavelengths. 10GBASE-LX4 also supports 10 kilometres (6.2 mi) over SMF. Until 2005 10GBASE-LX4 optical modules were cheaper than 10GBASE-LR optical modules. 10GBASE-LX4 is used by people who want to support both MMF and SMF with a single optical module. Because 10GBASE-LX4 uses four lasers it has a potential cost, size and power disadvantage compared to 10GBASE-LRM.
What is 10GBASE-CX4?
10GBASE-CX4 was the first 10G copper standard published by 802.3 (as 802.3ak-2004). It uses the XAUI 4-lane PCS (Clause 48) and copper cabling similar to that used by InfiniBand technology. It is specified to work up to a distance of 15 m (49 ft). Each lane carries 3.125 G baud of signaling bandwidth.n10GBASE-CX4 offers the advantages of low power, low cost and low latency, but has a bigger form factor than the newer single lane SFP+ standard and a much shorter reach than fibre or 10GBASE-T.
What is CFP?
CFP stands for C form-factor pluggable, it is a multi-source agreement to produce a common form-factor for the transmission high-speed digital signals. The c stands for the Latin letter C used to express the number 100 (centum), as the standard was primarily developed for 100 Gigabit Ethernet systems.The CFP transceiver is specified by a multi-source agreement (MSA) between competing manufacturers. The CFP was designed after the SFP interface, but is significantly larger to support 100Gb using 10 lanes in each direction (RX, TX) with 10Gb/s each. In March 2009, Santur demonstrated a 100 Gigabit pluggable CFP Transceiver prototype, Santur 100G CFP Transceiver Supported signalsCFP transceivers can support a single 100 Gbit/s signal like 100GbE or OTU4 or one or more 40 Gbit/s signals like 40GbE, OTU3, or STM-256/OC-768.
What is 100 Gigabit Ethernet?
40 Gigabit Ethernet, or 40GbE, and 100 Gigabit Ethernet, or 100GbE, are high-speed computer network standards developed by the Institute of Electrical and Electronics Engineers (IEEE). They support sending Ethernet frames at 40 and 100 gigabits per second over multiple 10 Gb/s or 25 Gb/s lanes. Previously, the fastest published Ethernet standard was 10 Gigabit Ethernet. They were first studied in November 2007, proposed as IEEE 802.3ba in 2008, and ratified in June 2010.  Another variant was added in March 2011.
The following nomenclature was used for the physical layers:

Physical layer

40 Gigabit Ethernet

100 Gigabit Ethernet

at least 1 m over a backplane


approximately 7 m over copper cable



at least 100 m over OM3 MMF



at least 125 m over OM4 MMF

at least 10 km over SMF



at least 40 km over SMF


serial SMF over 2 km


What is Local area network?
A local area network (LAN) is a computer network that connects computers and devices in a limited geographical area such as home, school, computer laboratory or office building.[1] The defining characteristics of LANs, in contrast to wide area networks (WANs), include their usually higher data-transfer rates, smaller geographic area, and lack of a need for leased telecommunication lines.
What is metropolitan area network?
A metropolitan area network (MAN) is a computer network that usually spans a city or a large campus. A MAN usually interconnects a number of local area networks (LANs) using a high-capacity backbone technology, such as fiber-optical links, and provides up-link services to wide area networks (or WAN) and the Internet.
What is Wide area network?
A wide area network(WAN) is a telecommunication network that covers a broad area (i.e., any network that links across metropolitan, regional, and national boundaries) Business and government entities utilize WAN to relay data among employees, clients, buyers, and suppliers from various geographical location. In essence this mode of telecommunication allows a business to effective carry out it's daily function regardless of location. This is in contrast with personal area networks (PANs), local area networks (LANs), campus area networks (CANs), or metropolitan area networks (MANs) which are usually limited to a room, building, campus or specific metropolitan area (e.g., a city) respectively.


What is Metro Ethernet?
Metro Ethernet is a computer network that covers a metropolitan area and that is based on the Ethernet standard. It is commonly used as a metropolitan access network to connect subscribers and businesses to a larger service network or the Internet. Businesses can also use Metro Ethernet to connect branch offices to their Intranet. Ethernet has been a well known technology for decades. An Ethernet interface is much less expensive than a SONET/SDH or PDH interface of the same bandwidth. Ethernet also supports high bandwidths with fine granularity,[clarification needed] which is not available with traditional SDH connections. Another distinct advantage of an Ethernet-based access network is that it can be easily connected to the customer network, due to the prevalent use of Ethernet in corporate and, more recently, residential networks. Therefore, bringing Ethernet in to the Metropolitan Area Network (MAN) introduces a lot of advantages to both the service provider and the customer (corporate and residential).


What is Synchronous optical networking?
Synchronous optical networking (SONET) and synchronous digital hierarchy (SDH) are standardized multiplexing protocols that transfer multiple digital bit streams over optical fiber using lasers or light-emitting diodes (LEDs). Lower data rates can also be transferred via an electrical interface. The method was developed to replace the Plesiochronous Digital Hierarchy (PDH) system for transporting larger amounts of telephone calls and data traffic over the same fiber without synchronization problems. SONET generic criteria are detailed in Telcordia Technologies Generic Requirements document GR-253-CORE. Generic criteria applicable to SONET and other transmission systems (e.g., asynchronous fiber optic systems or digital radio systems) are found in Telcordia GR-499-CORE. SONET and SDH, which are essentially the same, were originally designed to transport circuit mode communications (e.g., DS1, DS3) from a variety of different sources, but they were primarily designed to support real-time, uncompressed, circuit-switched voice encoded in PCM format. The primary difficulty in doing this prior to SONET/SDH was that the synchronization sources of these various circuits were different. This meant that each circuit was actually operating at a slightly different rate and with different phase. SONET/SDH allowed for the simultaneous transport of many different circuits of differing origin within a single framing protocol. SONET/SDH is not itself a communications protocol per se, but a transport protocol.

SONET/SDH Designations and bandwidths

SONET Optical Carrier Level

SDH level and Frame Format

Line Rate (kbit/s)





















What is Storage area network?
A storage area network (SAN) is a dedicated storage network that provides access to consolidated, block level storage. SANs primarily are used to make storage devices (such as disk arrays, tape libraries, and optical jukeboxes) accessible to servers so that the devices appear as locally attached to the operating system. A SAN typically has its own network of storage devices that are generally not accessible through the regular network by regular devices. The cost and complexity of SANs dropped in the early 2000s, allowing wider adoption across both enterprise and small to medium sized business environments.
What is Fibre Channel?
Fibre Channel, or FC, is a gigabit-speed network technology primarily used for storage networking. Fibre Channel is standardized in the T11 Technical Committee of the InterNational Committee for Information Technology Standards (INCITS), an American National Standards Institute (ANSI)–accredited standards committee. Fibre Channel was primarily used in the supercomputer field, but now, has become the standard connection type for storage area networks (SAN) in enterprise storage. Despite its name, Fibre Channel signaling can run on both twisted pair copper wire and fiber-optic cables.
Fibre Channel Variants



Throughput (Fullduplex) (MBps)*


















10GFC Serial




10GFC Parallel











What is Passive optical network?
Passive optical network is also called PON, it include EPON, APON,BPON,G-PON,10G-PON.

EPON (Ethernet PON) is part of IEEE standard Ethernet with options for 1/1 Gbit/s 10/1 Gbit/s and 10/10 Gbit/s. There are currently over 40 million installed EPON ports making it the most widely deployed PON technology globally. EPON is also the foundation for cable operators business services as part of the DOCSIS Provisioning of EPON (DPoE) specifications.
APON (ATM PON) was the first Passive optical network standard. It was used primarily for business applications, and was based on ATM.
BPON (Broadband PON) is a standard based on APON. It adds support for WDM, dynamic and higher upstream bandwidth allocation, and survivability. It also created a standard management interface, called OMCI, between the OLT and ONU/ONT, enabling mixed-vendor networks.
G-PON (Gigabit PON) is an evolution of the BPON standard. It supports higher rates, enhanced security, and choice of Layer 2 protocol (ATM, GEM, Ethernet). GPON networks have now been deployed in numerous carrier networks across the globe, and the trends indicate higher growth in GPON than other PON technologies.
10G-PON has 10 Gbit/s downstream and 2.5 Gbit/s upstream – framing is "G-PON like" and designed to coexist with GPON devices on the same network
What is 10G-EPON?
The 10 Gbit/s Ethernet Passive Optical Network standard, better known as 10G-EPON allows computer network connections over telecommunication provider infrastructure. The standard supports two configurations: symmetric, operating at 10 Gbit/s data rate in both , directions, and asymmetric, operating at 10 Gbit/s in the downstream (provider to customer) direction and 1 Gbit/s in the upstream direction.
In March 2006, the Institute of Electrical and Electronics Engineers (IEEE) 802.3 working group held a call for interest for a 10 Gbit/s Ethernet passive optical network study group. According to the CFI materials, representatives from the following companies supported the formation of the study group:[1] Advance/Newhouse Communications, Aeluros, Agilent, Allied Telesyn, Alloptic, Ample Communications, Astar-ODSM, Broadcom, Centillium Communications, China Netcom, China Telecom, Chunghwa Telecom, Cisco Systems, ClariPhy Communications, Conexant Systems, Corecess, Corning, Delta Electronics, ETRI, Fiberxon, FOTEK Optoelectronics, ImmenStar, Infinera, ITRI, KDDI R&D Labs., K-Opticom, Korea Telecom, NEC, OpNext, Picolight, Quake Technologies, Salira Systems, Samsung Electronics, Softbank BB, Teknovus, Teranetics, Texas Instruments, Telecom Malaysia, TranSwitch, UNH IOL, UTStarcom, Vitesse.
The 10/10G-EPON employs a number of functions that are common to other point-to-point Ethernet standards. For example, such functions as 64B/66B line coding, self-synchronizing scrambler, or gearbox are also used in 10GBASE-SR, 10GBASE-LR, 10GBASE-ER, 10GBASE-LRM, and 10GBASE-KR types of Ethernet links.
What is FTTX?
Fiber to the x (FTTx) is a generic term for any broadband network architecture that uses optical fiber to replace all or part of the usual metal local loop used for last mile telecommunications. The generic term originated as a generalization of several configurations of fiber deployment (FTTN, FTTC, FTTB, FTTH...), all starting by FTT but differentiated by the last letter, which is substituted by an x in the generalization.
FTTN - Fiber-to-the-node - fiber is terminated in a street cabinet up to several kilometers away from the customer premises, with the final connection being copper. Fiber-to-the-node is often seen as an interim step towards full FTTH and is currently used by telecoms service providers like AT&T, Deutsche Telekom, Telekom Austria and Swisscom to deliver advanced triple-play services.
FTTC - Fiber-to-the-cabinet - this is very similar to FTTN, but the street cabinet is closer to the user's premises; typically within 300m.
FTTB - Fiber-to-the-building or Fiber-to-the-basement - fiber reaches the boundary of the building, such as the basement in a multi-dwelling unit, with the final connection to the individual living space being made via alternative means.
FTTH - Fiber-to-the-home - fiber reaches the boundary of the living space, such as a box on the outside wall of a home. Active Ethernet Point-to-Point is fast emerging as the optimum architecture for delivering advanced triple-play services over FTTH networks because there is no limit on the distance between an operator‘s central office (CO) and a subscriber's home.
FTTP - Fiber-to-the premises - this term is used in several contexts: as a blanket term for both FTTH and FTTB, or where the fiber network includes both homes and small businesses.
What is Optical line termination( OLT)?
An optical line termination (OLT), also called an optical line terminal, is a device which serves as the service provider endpoint of a passive optical network. It provides two main functions:
1.to perform conversion between the electrical signals used by the service provider's equipment and the fiber optic signals used by the passive optical network.
2.to coordinate the multiplexing between the conversion devices on the other end of that network (called either optical network terminals or optical network units).
What is Transmission windows?

Each effect that contributes to attenuation and dispersion depends on the optical wavelength. The wavelength bands (or windows) that exist where these effects are weakest are the most favorable for transmission. These windows have been standardized, and the currently defined bands are the following:
Band Description Wavelength Range


What is Wavelength-division multiplexing(WDM)?
In fiber-optic communications, wavelength-division multiplexing (WDM) is a technology which multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths (colours) of laser light. This technique enables bidirectional communications over one strand of fiber, as well as multiplication of capacity. The term wavelength-division multiplexing is commonly applied to an optical carrier (which is typically described by its wavelength), whereas frequency-division multiplexing typically applies to a radio carrier (which is more often described by frequency). Since wavelength and frequency are tied together through a simple directly inverse relationship, the two terms actually describe the same concept.

Coarse WDM (CWDM)
Originally, the term "coarse wavelength division multiplexing" was fairly generic, and meant a number of different things. In general, these things shared the fact that the choice of channel spacings and frequency stability was such that erbium doped fiber amplifiers (EDFAs) could not be utilized. Prior to the relatively recent ITU standardization of the term, one common meaning for coarse WDM meant two (or possibly more) signals multiplexed onto a single fiber, where one signal was in the 1550 nm band, and the other in the 1310 nm band.
An interesting and relatively recent development relating coarse WDM is the creation of GBIC and small form factor pluggable (SFP) transceivers utilizing standardized CWDM wavelengths. GBIC and SFP optics allow for something very close to a seamless upgrade in even legacy systems that support SFP interfaces. Thus, a legacy switch system can be easily "converted" to allow wavelength multiplexed transport over a fiber simply by judicious choice of transceiver wavelengths, combined with an inexpensive passive optical multiplexing device. Passive CWDM is an implementation of CWDM that uses no electrical power. It separates the wavelengths using passive optical components such as bandpass filters and prisms. Many manufacturers are promoting passive CWDM to deploy fiber to the home.

Dense WDM( DWDM)
Dense wavelength division multiplexing, or DWDM for short, refers originally to optical signals multiplexed within the 1550 nm band so as to leverage the capabilities (and cost) of erbium doped fiber amplifiers (EDFAs), which are effective for wavelengths between approximately 1525–1565 nm (C band), or 1570–1610 nm (L band). EDFAs were originally developed to replace SONET/SDH optical-electrical-optical (OEO) regenerators, which they have made practically obsolete. EDFAs can amplify any optical signal in their operating range, regardless of the modulated bit rate. In terms of multi-wavelength signals, so long as the EDFA has enough pump energy available to it, it can amplify as many optical signals as can be multiplexed into its amplification band (though signal densities are limited by choice of modulation format). EDFAs therefore allow a single-channel optical link to be upgraded in bit rate by replacing only equipment at the ends of the link, while retaining the existing EDFA or series of EDFAs through a long haul route. Furthermore, single-wavelength links using EDFAs can similarly be upgraded to WDM links at reasonable cost. The EDFAs cost is thus leveraged across as many channels as can be multiplexed into the 1550 nm band.
What is TOSA and ROSA?
TOSA stands for Transmitter Optical Subassembly and ROSA stands for Receiver Optical Subassembly
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