New hardware could make FTTH expansion cheaper

A new way to solve the “last mile problem” and provide real fiber connections to households was developed by scientists and researchers from the UCL Optical Networks Group and UNLOC program in London as they designed a simplified optical receiver that could be mass-produced cheaply.
Although current networks are mostly composed with optical fiber, they usually terminate in cabinets away from the user premises and that last mile that goes from the cabinet to the end user is mostly made with copper, which slows down connections, because it is really expensive to install in every home the optical receiver needed to read the optical signals.
“We have designed a simplified optical receiver that could be mass-produced cheaply while maintaining the quality of the optical signal. The average data transmission rates of copper cables connecting homes today are about 300 Mb/s and will soon become a major bottleneck in keeping up with data demands, which will likely reach about 5-10 Gb/s by 2025. Our technology can support speeds up to 10 Gb/s, making it truly futureproof”, said Dr Sezer Erkilinc, lead researcher from UCL Electronic & Electrical Engineering.
The design of the optical receiver developed by UCL researchers is simplified because it contains a quarter of the connectors that are usually used in a conventional receiver. It is able to improve sensitivity and network reach compared to current technology. When commercialized, the cost of installing and maintaining a real FTTH network will be dramatically reduced.
 The laser stability of the receiver is currently being tested by the researchers, but Dr Erkilinc said once they it is quantified, they will be in a strong position to take the receiver design to trials and commercialize it.
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The status of FTTH on USA: What to know about it?

Given the growing demand for data on both fixed and mobile networks and the big size of the USA market, there is continuous pressure for operators to invest in fiber networks and to push connectivity closer to consumers.
In recent years the United States has seen increased activity from regional players as well as the major telcos and cablecos. Much of this activity was stimulated by Google Fiber following its investments in a number of markets. Although Google Fiber (now managed through Alphabet’s Access unit) began scaling back its efforts in late 2016, the company’s legacy has been profound. It encouraged the major providers to reduce pricing for their similar offers, stimulated interest among municipal leaders, and highlighted the fact that haphazard and potentially duplicated fiber deployments are no effective substitute for municipally-led wholesale fiber infrastructure accessible to any provider.
Local networks supported by municipal governments have also sprung up despite the lobbying efforts of AT&T and Verizon aimed at preventing local competition. However, for their part AT&T and Verizon have both refocused efforts on FTTP rather than FTTN, looking at the benefits of current investments for decades to come. G.fast is also being rolled out, to a lesser degree, in areas where FTTP is less feasible, while a growing number of cablecos have also deployed and DOCSIS3.1.
In the United States, the largest fiber to the premises (FTTP) deployment to date is Verizon’s FiOS, which covers 32 million people in the Northeastern United States. Verizon is the only Regional Bell Operating Company thus far to deploy FTTP on a large scale.
Verizon’s initial FTTP offering was based on broadband passive optical network (BPON) technology. Verizon has already upgraded to Gigabit PON or GPON, a faster optical access technology capable of providing 1Gbit/s speeds to consumers.
Lightower has the second most available fiber network, with 19 million people in the Northeast and the Midwest. Frontier is available to 10 million people across the country, and Monmouth is available to 8 million people in New Jersey.
The biggest benefit of fiber is that it can offer much faster speeds over much longer distances than traditional copper-based technologies like DSL and cable. The actual service depends on the company providing the service, but in most cases, fiber is the best bang for the buck broadband and future-proof for as long as we can tell. Even if typical broadband speeds become 1000 times faster in 20 years, a single existing fiber-optic connection can still support it.

FTTH PON evolution: GPON to NG-PON2

by http://www.fiber-mart.com

Evolution Path: GPON to NG-PON2
 After GPON Recommendations were done, FSAN and ITU-T continued the study of NG-PONs and defined the first phase of NG-PONs as systems that offer low costs, large capacity, wide coverage, full service, and interoperability with existing technology. FSAN and ITU-T members also agree that long term PON evolution will be driven by new scenarios if coexistence with legacy systems is not required. In addition to time-division multiplexing (TDM) PONs, other technologies for NG-PON could also be taken into account.
 The key to a successful upgrade is to make sure that no changes are required to the optical distribution network. This requires the operator to place a coexistence element (CE) in the central office, and to make sure the current GPON ONTs/ONUs are equipped with the WDM filters as described in ITU-T G.984.5.
  The evolution to a NG-PON2 network can be performed by inserting a NG-PON2 blade at the optical line terminal (OLT) and routing the fibres to the coexistence element (CE). Figure following: Coexistence of GPON and NG-PON2
What is NG-PON2
  NG-PON2 (Next-Generation Passive Optical Network 2) is a 2015 telecommunications network standard for a passive optical network (PON). The standard was developed by ITU and details an architecture capable of total network throughout of 40 Gbps, corresponding to up to 10 Gbps symmetric upstream/downstream speeds available at each subscriber.
  A passive optical network is a last mile, fibre-to-the-x telecommunications network that broadcasts data through fibre optic cables. PONs are managed by passive optics such as unpowered splitters and filters, offering high reliability and low cost compared to active networks. The PON data stream is generally converted to a more traditional service such as Ethernet and Wi-Fi at the subscriber’s location.
  NG-PON2 is compatible with existing PON fibre by replacing optical line terminal (OLT) at the central office, and the optical network unit (ONU) near each end-user.

Picking the right fiber connector – PC, UPC or APC

I wrote a blog post some days ago on the different types of connectors available, which sparked a great deal of feedback and discussion, demonstrating how important the whole topic is to both fiber installers and network planners alike. Thanks again to everyone around the world that contributed, both directly on the PPC’s blog and through various social groups.

To recap, I covered SC, LC, FC, ST and MTP/MPO connectors, and looking through the comments I thought it would be beneficial to focus on one area that the original post deliberately didn’t cover – the differences between Angled Physical Contact (APC) and Ultra Physical Contact (UPC) connectors. Beside one having a green body and the other being colored blue, the different ways they both treat light is crucial in planning a network, as several readers pointed out.

To help us understand all this jargon, let’s look back at why the original Flat Fiber Connector evolved into the Physical Contact (PC) connector and then onto UPC and APC.

The primary issue with Flat Fiber connectors is that when two of them are mated it naturally leaves a small air gap between the two ferrules; this is partly because the relatively large end-face of the connector allows for numerous slight but significant imperfections to gather on the surface. This is not much use for single mode fiber cables with a core size of just 8-9 µm, hence the necessary evolution to Physical Contact (PC) Connectors.

The PC is similar to the Flat Fiber connector but is polished with a slight spherical (cone) design to reduce the overall size of the end-face. This helps to decrease the air gap issue faced by regular Flat Fiber connectors, resulting in lower Optical Return Loss (ORL), with less light being sent back towards the power source.

Building on the convex end-face attributes of the PC, but utilizing an extended polishing method creates an even finer fiber surface finish: bringing us the Ultra Physical Contact (UPC) connector. This results in a lower back reflection (ORL) than a standard PC connector, allowing more reliable signals in digital TV, telephony and data systems, where UPC today dominates the market. Most engineers and installers believe that any poor performance attributed to UPC connectors is not caused by the design, but rather poor cleaving and polishing techniques. UPC connectors do have a low insertion loss, but the back reflection (ORL) will depend on the quality of the fiber surface and, following repeat matings/unmatings, it will begin to deteriorate.

So what the industry needed was a connector with low back reflection, that could sustain repeated matings/unmatings without ORL degradation. Step forward the Angled Physical Contact (APC) connector.

Although PC and UPC connectors have a wide range of applications, some instances require return losses in the region of one-in-a-million (60dB). Only APC connectors can consistently achieve such performance. This is because adding a small 8° angle to the end-face allows for even tighter connections and smaller end-face radii. Combined with that, any light that is redirected back towards the source is actually reflected out into the fiber cladding, again by virtue of the 8° angled end-face.

It is true that this slight angle on each connector brings with it rotation issues that Flat, PC and UPC connectors simply don’t have. It is also the case that the three aforementioned connectors are all inter-mateable, whereas the APC isn’t. So, why then is the APC connector so important in fiber optics?

 

The uses of APC connectors

The best feedback examples from my previous blog came from people experienced with Fttxand Radio Frequency (RF) applications. The advance in analogue fiber optic technology has driven demand for it to replace more traditional coaxial cable (copper). Unlike digital signals (which are either ON or OFF), the analogue equipment used in applications such as DAS, FTTH and CCTV is highly sensitive to changes in signal, and therefore requires minimal back reflection (ORL).

 

APC ferrules offer return losses of -65dB. In comparison a UPC ferrule is typically not more than -55dB. This may not sound like a major difference, but you have to remember that the decibel scale is not linear. To put that into context a -20dB loss equates to 1% of the light being reflected back, -50dB leads to nominal reflectance of 0.001%, and -60dB (typical of an APC ferrule) equates to just 0.0001% being reflected back. This means that whilst a UPC polished connector will be okay for a variety of optical fiber applications, only an APC will cope with the demands of complex and multi-play services.

 

The choice is even more important where connector ports in the distribution network might be left unused, as is often the case in FTTx PON network architectures. Here, optical splitters are used to connect multiple subscriber Optical Network Units (ONUs) or Optical Network Terminals (ONTs). This is not a problem with unmated APC connections where the signal is reflected into the fiber cladding, resulting in typical reflectance loss of -65dB or less. The signal from an unmated UPC connector however, will be sent straight back towards the light source, resulting in disastrously high loss (more than 14dB), massively impeding the splitter module performance.

Picking the right physical contact connector

Looking at current technology, it’s clear that all of the connector end-face options mentioned in this blog post have a place in the market. Indeed, if we take a sidestep across to Plastic Optical Fiber (POF) applications, this can be terminated with a sharp craft knife and performance is still deemed good enough for use in the high-end automotive industry. When your specification also needs to consider cost and simplicity, not just optical performance, it’s hard to claim that one connector beats the others. Therefore whether you choose UPC or APC will depend on your particular need. With those applications that call for high precision optical fiber signaling, APC should be the first consideration, but less sensitive digital systems will perform equally well using UPC. Fiber-Mart can supply many kinds fiber connectors. If you have any questions or requirement of fiber connectors,welcome to contact us: product@fiber-mart.com.

Singlemode fiber and multimode fiber different and selection method(2)

The application of fiber optics is being gradually extended from the trunk or the computer room to the desktop and residential users, which means that more and more users who do not understand the characteristics of the fiber have come into contact with the fiber optic system. Therefore, when designing fiber link systems and selecting products, full consideration should be given to the current and future application requirements of the system, use of compatible systems and products, the greatest possible ease of maintenance and management, and adaptation to the ever-changing field conditions and user installation requirements.

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1. Can a fiber optic connector be terminated directly on a 250 μm fiber?  

 

Loose sleeve fiber optic cable contains bare fiber with an outer diameter of 250 μm, which is very small and fragile. It is unable to fix the fiber and is not enough to support the weight of the fiber optic connector and is very insecure. The connector is terminated directly on the fiber optic cable. At a minimum, a 900 μm tight jacket is required to wrap around the 250 μm fiber to protect the fiber and support the connector.

2. Can the FC connector be connected directly to the SC connector?

Yes, this is just a different connection method for two different types of connectors.
If you need to connect them, you must select a mixed adapter and use the FC/SC adapter to connect the FC connector and the SC connector at both ends. This method requires that the connectors should all be flat ground. If you absolutely need to connect APC connectors, you must use a second method to prevent damage.

The second method is to use a hybrid jumper and two connection adapters. Hybrid patch cords use different types of fiber connectors at both ends. These connectors will connect to the place where you need to connect. In this way, you can use a universal adapter to connect the system in the patch panel, but bring the system budget to budget. The increase in the number of connector pairs.

3. The fixed connection of optical fibers includes mechanical optical fiber connection and thermal welding. What are the selection principles for mechanical optical fiber connection and thermal welding?

Mechanical fiber optic connection, commonly known as fiber optic cold connection, refers to an optical fiber connection method in which a single or multi-fiber optical fiber is permanently connected through a simple connection tool and a mechanical connection technology without the need of a thermal fusion bonding machine. In general, mechanical splices should be used in place of thermal fusion when splices are made at a small number of cores dispersed at multiple locations.

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Mechanical fiber optic connection technology is often used in engineering practices such as line repairs and small-scale applications in special occasions. In recent years, with the large-scale deployment of fiber-to-the-desktop and fiber-to-the-home (FTTH), it has been recognized that mechanical fiber optic connection is an important means of fiber optic connection.

For fiber-to-the-desktop and fiber-to-the-home applications with a large number of users and geographically dispersed features, when the scale of the users reaches a certain level, the construction complexity and construction personnel and fusion splicer cannot meet the time requirements for users to open services. Because of the simple operation, short training cycle, and low equipment investment, the mechanical fiber connection method provides the most cost-effective solution for optical fiber connection for large-scale deployment of optical fibers. For example, in the high corridors, narrow spaces, insufficient lighting, inconvenient on-site power and other occasions, mechanical fiber optic connection provides a convenient, practical, fast and high-performance optical fiber continuation means for design, construction and maintenance personnel.

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 4. What is the difference between fiber optic splice enclosure requirements and fiber optic splice closures used in telecom operators’ outdoor lines in fiber-to-the-home systems?

First of all, in the fiber-to-the-home system, it is necessary to reserve the position of the optical splitter installation and termination, accommodation, and protection of the jumper to and from the optical splitter in the joint box according to actual needs. Because the actual situation is that the optical splitter may be located in the cable joint box, optical cable transfer box, wiring box, ODF and other facilities, and in which the optical cable termination and distribution.

Secondly, for residential quarters, the optical fiber cable splice box is installed in a buried manner. Therefore, the optical cable splice box has higher requirements for buried performance.

In addition, in the fiber-to-the-home project, it may be necessary to consider the entry and exit of a large number of small-core optical cables.