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Passive Optical Network (PON) Knowledge Introduction

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A Passive Optical Network (PON) is a system that transmits all or most of the fiber cabling and signals to end-users. Depending on where the PON terminal is located, the system can be described as fiber-to-the-curb (FTTC), fiber-to-the-building (FTTB), or fiber-to-the-home (FTTH).
The optical distribution network does not contain any electronic devices and electronic power supply, ODN splitter consist of the passive components, and other components do not require expensive active electronic devices. A passive optical network includes an optical line terminal (OLT) installed at a central control station and a set of optical network units (ONUs) installed at customer side. The Optical Distribution Network (ODN) between the OLT and the ONU contains optical fibers as well as passive optical splitters or couplers.
The structure of the PON system is mainly composed of an Optical Line Terminal (OLT) at the ca0rrier’s office, an Optical Distribution Network (ODN) including passive optical components, an ONU (Optical Network Unit / ONT (Optical Network Terminal). The difference is that the ONT is directly located at the user end, and there are other networks between the ONU and the user, such as Ethernet) and the network element management system (EMS), and usually adopts point-to-multipoint Tree topology.
Introduction
Fiber is so cheap and easy to use, so FTTx (Fiber To The X, fiber access) as a new generation of broadband solutions are widely used to provide users with high-bandwidth, full-service access platform. The FTTH (Fiber To The Home, FTTH, the fiber is directly connected to the user’s home) is also known as the best business transparent network, is the ultimate way of access network development.
The FTTx is how to work? In many kinds of schemes, P2MP optical access mode PON (Passive Optical Network, passive optical network) is the best choice. PON is an optical distribution network (ODN) which is applied to an access network, an OLT and a plurality of client devices (ONU / ONT) through passive optical cables, optical splitters/combiners, etc., Connected network. As shown on the right.
• OLT (Optical Line Terminal, optical line terminal)
• ONU (Optical Network Unit, optical network unit)
• ONT (Optical Network Terminal, optical network terminal)
• ODN (Optical Distribution Network, optical distribution network)
Both the ONU and the ONT belong to the user equipment. The difference between them lies in that the ONT is located directly on the user end, and there are other networks between the ONU and the user, such as Ethernet.
The key point of “passive” is that the ODN between the OLT and the ONU is an optical access network without any active electronic equipment. Because of this “passive” feature, the purely PON network can avoid electromagnetic Interference and lightning effects reduce line and external device failure rates, improve system reliability, and reduce maintenance costs.
PON technology began to develop in the 1990s, ITU (International Telecommunication Union) started from APON (155 M), developed BPON (622 M), and to GPON (2.5 G); meanwhile, in this century, due to Ethernet technology widespread application, IEEE also developed EPON technology in Ethernet technology. At present, PON technologies for broadband access mainly include EPON and GPON, and the two adopt different standards. The future development is higher bandwidth, such as EPON / GPON technology has developed 10G EPON / 10G GPON, the bandwidth has been a higher upgrade.
Click here to learn more about the difference and comparison between GPON and EPON
PON Features
The complexity of PON lies in the signal processing technology. In the downlink direction, the switch sends the signal is broadcast to all users. In the uplink direction, each ONU must use some kinds of multiple access protocols such as TDMA (Time Division Multiple Access) protocols to complete the shared transmission channel information access. Currently used for broadband access PON technologies are: EPON and GPON.
PON Standards
• ITU-T G.983
APON (Passive Optical Network), This is the first passive optical network standard, which is based on ATM and is mainly used in commercial applications. BPON (Broadband Passive Optical Network),  This is an APON-based standard that adds support for WDM, dynamic and high-speed uplink bandwidth allocation, and endurance. BPON also created a management interface standard OMCI, authorized between the OLT and ONU / ONT hybrid supplier network.
• IEEE 802.3ah
EPON or GEPON (Ethernet Passive Optical Network), This is an IEEE / EFM standard for data using Ethernet packets. The 802.3ah standard is now part of the IEEE 802.3 standard and there are now about 15 million EPON ports in use. In 2008, China vigorously developed EPON technology. It is estimated that as of the end of 2008, China had a total of 2 million EPON installation users.
• ITU-T G.984
GPON (Gigabit PON, Gigabit Passive Optical Network), This is a BPON standard development. GPON supports higher rates, enhanced security and optional Layer 2 protocols (ATM, GEM, Ethernet). In mid-2008, 900,000 lines had been installed by the company, and British Telecom And AT & T are conducting advanced trials.
• IEEE P802.3av
10G-EPON (10 Gigabit Ethernet PON) is an IEEE dedicated project that is backward compatible with 802.3ah standard EPON in order to achieve 10 Gbit/s. 10Gig EPON will use separate wavelengths for 10G and 1G downstream. 802.3av will continue to be isolated using separate wavelength TDMA for uplink between 10G and 1G. 10G-EPON will also be WDM-PON compatible (as defined by WDM-PON).This allows multiple wavelengths to be used in both directions It is possible.
• SCTE IPS910
RFoG (RFoverGlass) is an SCTE interface practice subcommittee standard for point-to-multipoint (P2MP) operation with wavelength planning compatible data PON solutions such as EPON, GEPON or 10Gig EPON.
PON technology status
The traditional downlink data flow of PON system adopts a broadcasting technology, and the uplink data flow uses TDMA technology to solve the problem of multiplexing signals in each direction of multi-user. The traditional PON technology uses WDM technology to implement single-fiber bidirectional transmission on optical fibers and solve the multiplexing transmission of signals in two directions. PON generally by the optical line terminal (OLT), optical splitter (ODU), the user terminal (ONU) 3 parts. Currently, PON technologies widely used in the current network include two mainstream technologies, EPON and GPON. The bandwidth for EPON uplink and downlink is 1.25 Gbit / s, the downlink bandwidth for GPON is 2.5 Gbit / s, and the uplink bandwidth is 1.25 Gbit / s.
Currently, in the actual FTTx application scenario, most EPON / GPONs only have an Ethernet interface, and POTS and 2M interfaces are optional. However, from the technical standards, EPON / GPON can achieve multi-service access such as IP service and TDM service and realize QoS classification.
EPON / GPON can transmit the clock synchronization signal. The frequency synchronization signal can be extracted from the external line through the STM-1 interface or the GE interface of the OLT. In this case, the OLT needs to support synchronous Ethernet, and can also be input from the external BITS on the OLT device The clock signal, as a common clock source of the PON, is kept in frequency synchronization with the clock source.
PON Standards Development
Although 10G EPON and PON have not yet been commercialized on a large scale, the PON technology at a rate of more than 10 Gbit / s is the focus and hot point of the research of ITU-T and FSAN in the past two years. The relevant technical standards of XG-PON1 have become mature, NG-PON2 standard after XG-PON1 ITU-T related standards for GPON, XG-PON1, and NGPON2 The framework has basically been completed. The emphasis on recent multi-wavelength extensions is the focus of recent technical studies where FSAN has identified TWDM-PON as the technology of choice for NG-PON2 in the future, but the G. multi-standard that standardizes multiple technologies in ITU-T SG15 has also been largely completed.
PON Advantages
• Energy consumption
Imagine the ongoing costs of energy-inefficient equipment and equipment needed to operate in traditional Ethernet LANs and the additional energy costs to cool or heat the closet space. Achieving More Than 50% Savings by Eliminating Active Switches, Uninterruptible Power Supplies (UPS) Devices, and Additional Power Demand is a year-by-year cost-effective annuity.
• Save space
The PON architecture requires a separate data center room, with splitters on each floor, usually hidden in a maintenance or electrical cabinet. Traditional Ethernet closets require more than 100 to 200 square feet of floor space per floor, and these spaces are returned to customers for functional or even potential revenue-generating space. Just reducing the weight of the ceiling wiring is amazing. BICSI announced that the traditional 114-port copper Ethernet design required 890 pounds of copper and fiber optic backbone; in contrast, the 114-port PON design required only 180 pounds of fiber optic cable, about one-fifth the size of a traditional design.
• Installation Savings
Which sounds easier? Installing and Terminating (5) Category 6A UTP cable to each hotel room, or (1) Fiber optic cable in each room … Each floor without cable tray, rack, and traditional cabinet. Few components require grounding and coding, and fire through holes are much smaller and less expensive.
• Safety
Passive optical networks LANs are naturally more secure than Ethernet LANs for the simple reason that optical fibers are not as conductive as copper. Unfortunately, electronic-based services are known as security risk points because copper emits electromagnetic radiation (EMR) signals. These signals contain all the information copper carries at the time and can be intercepted and reconstructed on nearby devices.
• Speed and bandwidth
We have already mentioned the potential of speed and bandwidth, which is why in the 90s we wanted to achieve the “fiber to the desktop” dream. The reality now is that, for example, new hotels that have moved to PON are now gaining the benefits of improved high-speed Internet access (HSIA) performance from their guests, improving customer satisfaction surveys and increasing occupancy rates.

What is Fiber Optic Adapter

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Fiber optic adapters (also known as Fiber couplers, Fiber Adapter ) are designed to connect two optic cables together. They have a single fiber connector (simplex), dual fiber connector (duplex) or sometimes four fiber connector (quad) versions. The optical fiber adapter can be inserted into different types of optical connectors at both ends of the optical fiber adapter to realize the conversion between different interfaces such as FC, SC, ST, LC, MTRJ, MPO and E2000, and is widely used in optical fiber distribution frames (ODFs) Instruments, providing superior, stable and reliable performance.
Features of Fiber Optic Adapter
The optical fibers are connected by an adapter through its internal open bushing to ensure the maximum connection between the optical connectors. In order to be fixed in a variety of panels, the industry also designed a variety of finely fixed flange.
Transformable optical adapters are available with fiber optic connectors of different interface types on both ends and provide a connection between APC faceplates. Duplex or multi-adapter adapts to increase installation density and save space.
Fiber Optic Adapter types
FC Fiber Optic Adapter
This fiber optic adapter was first developed by Japan NTT. FC is an acronym for FERRULE CONNECTOR, indicating that its external reinforcement is the use of the metal sleeve, fastening the way for the buckle. The earliest, FC type connector, the docking end of the ceramic pin. Such connectors are simple in structure, easy to operate and easy to manufacture. However, the fiber end face is more sensitive to dust, and it is easy to produce Fresnel reflection and it is difficult to improve the return loss performance. Later, this type of connector has been improved, the use of docking the spherical end of the pin (PC), while the external structure has not changed, making the insertion loss and return loss performance has been greatly improved.
SC Fiber Optic Adapter
This is a kind of optical fiber connector developed by Japan NTT Corporation. The shell is rectangular, the pin and the coupling sleeve used in the structure of the same size and FC type. One end of the pin to use more PC or APC grinding method; fastening method is the use of plug pin type, without rotation. Such connectors are inexpensive, easy to plug and unplug, low insertion loss variations, high compressive strength, and high installation density.
DIN47256 Fiber Optic Adapter
This is a connector developed by Germany. The pins and coupling sleeves used in this connector are the same size as the FC type and the PC process is used for the end face processing. Compared with the FC type connector, the structure is more complex, and the internal metal structure has a control pressure spring to prevent the end face from being damaged due to the excessive insertion pressure. In addition, this connector has higher mechanical accuracy and therefore smaller insertion loss values.
MT-RJ Fiber Optic Adapter
MT-RJ started with the MT connector developed by NTT with the same latching mechanism as the RJ-45 type LAN electrical connector. Alignment of the optical fiber with guide pins mounted on both sides of the small bushing made it easy to communicate with the optical transceiver Machine connected to the connector end of the optical fiber for the dual core (0.75MM spacing) array design is mainly used for data transmission next generation high-density fiber optic connectors.
LC Fiber Optic Adapter
The lc-type connector is a well-known BELL (Bell) Institute of research and development, the use of convenient modular jack (RJ) latch mechanism made. The pins and sleeves used are half the sizes used for normal SC, FC, etc., at 1.25mm. This will increase the density of fiber optic connectors in fiber distribution frames. Currently, in the single-mode SFF, LC type of connector has actually occupied the dominant position, the application of multi-mode is also growing rapidly.
MU Fiber Optic Adapter
The MINIATURE UNIT COUPLING connector is the world’s smallest single-core fiber optic connector developed by NTT based on the currently used SC-type connector. The connector uses a 1.25MM diameter sleeve and self-holding mechanism, the advantage is that it can achieve high-density installation. NTT has developed the MU connector family with MU’s L.25MM diameter bushings. They have socket type connectors for optical cable connections; backplane connectors with the self-holding mechanism and simplified sockets for connecting LD / PD modules and plugs Wait. Demand for MU-type connectors will also grow rapidly as fiber-optic networks become more capable of larger bandwidths and DWDM technologies are widely used.
MTP/MPO Fiber Optic Adapters
Unlike the single-core SC fiber optic adapters, the SC fiber optic adapters are internally equipped with a ceramic ferrule that is precisely aligned through the ferrule when the SC connector ferrule is connected, while the MPO / MTP adapter is connected using an MPO / MTP Precise connection of two guide holes with a diameter of 0.7mm and a guide pin on the left and right ends of the ferrule. MPO / MTP adapters are widely used in communication system base stations, optical fiber distribution frames (ODFs) in building rooms, MPO / MTP cassette module, and various test instruments.

Do you know the transceiver laser types?

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Lasers are the core devices of optical transceivers, which injecting current into semiconductor materials and injecting laser light through the photon oscillations and gains in the resonator. At present, the most commonly used lasers are VCSEL, FP, and DFB laser. The difference between them is that semiconductor materials and resonator structures. DFB lasers are more expensive than FP lasers. The optical modules of transmission distance within 40km generally use VCSEL, FP lasers; transmission distance ≥ 40km generally use DFB lasers. Do you know all the transceiver laser types? Let us learn this knowledge.
LED Laser
Light-emitting diode referred to as LED. Made of a compound containing gallium (Ga), arsenic (As), phosphorus (P), nitrogen (N). Visible light is emitted when electrons recombine with holes and thus can be used to make light emitting diodes. In the circuit and equipment as a light, or composed of text or digital display. Gallium arsenide diode red, gallium phosphide diode green, silicon carbide diode yellow, gallium nitride diode blue. Due to the chemical nature of organic light-emitting diode OLED and inorganic light-emitting diode LED.
For optical fiber communication systems, LEDs are the best light source of choice if the multimode fiber is used and the bit rate is under 100-200Mb/s while only requiring input optical power of tens of microwatts. Compared with the semiconductor laser, because the LED does not need thermal stability and light stabilization circuit, so the LED drive circuit is relatively simple, its production cost is low, high yield LED emission spectrum line light, poor directivity, its own response speed Slow, so only for the lower speed communication system. The LED laser commonly used in 155M 1×9 multimode transceivers.
VCSEL Laser
Vertical-Cavity Surface-Emitting Laser (VCSEL) is a type of semiconductor laser whose laser is perpendicular to the top surface It is made of a separate chip that is generally cut with a slit, and the edge-emitting laser is different from the edge-emitting laser. VCSELs typically use 850nm wavelengths for short-range transmission of Gigabit Ethernet to 10GbE SR multimode fiber.
VCSEL laser has many advantages over edge-beam lasers in the production process. Edge-beam lasers cannot be tested after production. If an edge-emitting laser does not work, it is a waste of processing time and material processing time, either because of poor contact or poor material growth. However, VCSEL can be tested its quality and troubleshoot any manufacturing process. For example, if the paths between the dielectrics are not completely and cleanly connected, the top metal layer is not in contact with the test metal layer during the pre-packaged test and the test result is incorrect. Further, since the laser light emitted from the VCSEL is perpendicular to the reaction zone, and edge emitting laser light emitted in parallel to the reaction zone contrary, there can be tens of thousands of VCSEL to be processed on a three-inch large gallium arsenide chip simultaneously. In addition, even though VCSELs require more labor and finer material in the manufacturing process, more predictable production results can be controlled.

Differences Between FBT Splitter and PLC Splitter

In future fiber networks, splitters provide capabilities that help users maximize the functionality of optical network circuits.according to different manufacture technologies, fiber optic splitters can be divided into PLC splitter and FBT splitter.

In future fiber networks, splitters provide capabilities that help users maximize the functionality of optical network circuits.according to different manufacture technologies, fiber optic splitters can be divided into PLC splitter and FBT splitter.

What is Fiber Optic Splitter?

Fiber Optic splitter is suitable for a fiber optic signal to be decomposed into mufti-channel optical signal output.

Fiber splitters are comprised of three fibers – two fiber legs on one side that overlap inside a junction with a third fiber at the common end. The fiber type used in each leg is typically the same, but can also be custom configured to have different fiber core diameters or wavelength ranges. fiber splitters are good for mixing light from two different locations and delivering it through a single fiber to a spectrometer or sample.  This ability can be used to combine illumination from two different light sources, or to mix light collected from two different sampling points before delivery to a spectrometer.

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Optical Splitter is used to split the fiber optic light into several parts at a certain ratio. It is an important component used in Passive Optical Network (PON), therefore also called PON Splitter. There are mainly two kinds of PON splitters: one is the traditional fused type splitter known as FBT Coupler or FBT WDM splitter, which features competitive price; the other is the PLC Splitter based on the PLC (Planar Lightwave Circuit) technology, which has a compact size and suits for density applications. fiber optic splitter, also known as a beam splitter, is based on a quartz substrate of an integrated waveguide optical power distribution device, similar to a coaxial cable transmission system. The optical network system also needs to be an optical signal coupled to the branch distribution. In which requires the fiber optic splitter is one of the most important passive devices in the optical fiber link, is optical fiber tandem device with many input terminals and many output terminals, especially applicable to a passive optical network (EPON, GPON, BPON, FTTX, FTTH etc.) to connect the MDF and the terminal equipment and to achieve the branching of the optical signal.

FBT Splitters

FBT splitter is made out of materials that are easily available, for example steel, fiber, hot dorm and others. All of these materials are low-price, which determines the low cost of the device itself. Fused Biconical Taper (FBT) is used for splitting or combining optical signals and is tied to two or more fibers, and then melted in a cone machine, pull tensile and real-time monitoring of changes in splitting ratio, melt tensile splitting ratio to meet the requirements end, wherein one end of a fiber optic reserved ( The remaining cut off) as the input terminal and the other end a multitude of road outputs. Mature tapering process can only pull 1 × 4. 1 × 4 or more devices, with a plurality of 1 × 2 connected together. Then the whole package in the splitter box. The splitting or coupling ratio is controlled and can be modified upopn costumer request as well as the amount of splitting ports. The FBT coupler supports dicrete wavelength window.

fbt.jpg

PLC Splitters

PLC splitter manufacturing technology is more complex. It uses semiconductor technology (lithography, etching, developer technology) production, hence it is more difficult to manufacture. PLC refers to planar lightwave circuit. As a micro-optical device, PLC splitter uses an optical chip to split the input signal into various outputs. At the edge of the chip, there is a light circuit in ribbon form mounted on a carrier and fibers. PLC splitter typically adopts silica glass as the material of lightwave circuit and accepts different types of polished finishes. The substrate, waveguide and lid are three basic layers of the PLC splitter. For different applications, PLC splitters can be further categorized into different types including bare PLC splitters, blockless PLC splitters, ABS PLC splitters, LGX box PLC splitters, mini plug-in type PLC splitters, tray type PLC splitters and 1U rack mount PLC splitters.

 plc

Differences Between FBT Splitter and PLC Splitter

In this part, we will take a look at the main differences between FBT splitter and PLC splitter , which are listed in following.

 

PLC_Table.PNG

PLC splitters are optimal split applications since they facilitate the construction of many optical circuits in a compact size. although the outer appearance and size of FBT and PLC fiber splitter seem rather similar, their internal technologies and specifications differ in various ways. Fiber-Mart provides both PLC splitters and FBT coupler splitters for EPON/GPON Systems.any question pls not hesitate to contact us. E-mail:service@fiber-mart.com

What is Power-over-Ethernet (PoE)?

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PoE Definition

Short for Power over Ethernet, PoE is a standard that allows Ethernet cables to simultaneously transmit data and power using a single network cable. This allows system integrators and network installers to deploy powered devices in locations that lack electrical circuitry. PoE eliminates the expense of installing additional electrical wiring which entails hiring professional electrical installers to ensure that strict conduit regulations are followed. Typical PoE users are businesses adding to their network or adding VoIP phones in buildings where new power lines would be expensive or inconvenient.

What are the advantages of Power over Ethernet?

Cost savings– PoE significantly reduces the need for electricians to install conduit, electrical wiring, and outlets throughout the enterprise.   With PoE, only one cable – a simple CAT-5 Ethernet – is required.
Quick Deployment– PoE simply requires plugging in networking cabling to the proper equipment in order to function correctly.
Flexibility– Network administrators can deploy powered devices at nearly any location. Shielded cabling can be used for outdoor environments. Industrial-grade powered devices can be used for industrial environments.
Safety– Because PoE utilizes a relatively low voltage, it presents low risks of electrical hazards.
Reliability– PoE falls under IEEE’s strict 802.3 standard umbrage.
Scalability– PoE makes it simple to add new equipment to a network.

PoE Applications

VoIP phones
IP cameras
Wireless Access Points
PoE lighting
ATM machines
IP Intercoms
Security Card Readers
IP Clocks
Vending Machines

802.3af and 802.3at PoE Standards

There are currently two PoE standards available. The 802.3af standard supports 15.44 watts of power. But even though 802.3af Powered Sourcing Equipment (PSE) are able to transmit 15.44 watts of power, powered devices (PDs) can only reliably receive 12.95 watts of power due to power dissipation. In 2009, IEEE introduced the higher powered 802.3at standard, also known as PoE+. The standard supports 30 watts of power, but in a similar fashion to the 802.3af standard, power dissipation causes powered devices to receive slightly lower amounts of power, specifically 25.5 watts of power.

IEEE is currently overseeing yet another higher powered PoE standard. As the utility of PoE expands beyond the networking sector, higher powered PoE will be able to support nurse call systems, the point of sale systems, IP turrets used by financial traders, and higher powered IP cameras such as PTZ Cameras, among many other applications. 802.3bt, also known as PoE++, the new standard is expected to be ratified in early 2017, will utilize all four twisted pairs to transmit power. The 802.3bt standard will be able to achieve 49-70 watts of power using this method. The new standard will essentially combine both Mode A and Mode B to achieve the higher voltage. Some sources even site that the standard will be able to supply up to 100 watts of DC power. This newer standard will not only allow for higher power but will also be able to support 10 Gbps connections. Type A specifies for 60W (50 watts of power) and Type B specifies for about 100 watts of power (approximately 80 watts of power with power dissipation).

40G & 100G Optical Transceivers Basics

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A recent report from market research company LightCounting talks about the 40G & 100G optical transceivers basics, here are the details.

40G and 100G have two main types in the data center. Short reach (SR4) for ~100 meters transmission on multimode fiber and Long Reach (LR4) for 100 meters to 10km using single-mode fiber. We can use SR/LR transceivers to connect compute clusters and various switches layers in data centers. 40G transceivers are typically deployed as four 10G lanes in QSFP or CFP MSAs. 40G SR transceiver uses 8 multi-mode fibers, VCSEL lasers, and the QSFP MSA. Using edge-emitting lasers and multiplexes the four 10G lanes onto two single-mode fibers, 40G LR4 reach a 10km distance per CFP MSA, CFP/2 or QSFP28 MSAs. The 40G SR4 and LR4 transceivers can be used in the same QSFP switch port without any issues.

100G SR10 transceivers use 20 multi-mode fibers, VCSELs and the CXP MSA, the 100G LR4 transceivers uses CFP form and 2 single-mode fibers. The 100G SR10 CXP transceivers and AOCs are typically designed for the link of large aggregation and core switches at <50 meters. Since 2008, 40G QSFP transceivers and AOCs have been available, but until 2012, several transceiver companies announced CXP 100G SR transceivers.