DO You Know Variable Optical Attenuator?

Optical Attenuator is one part of passive optical components. It’s widely used in fiber optic communications to reduce optical fiber power at a certain level. Variable optical attenuator is one of optical attenuator. Now I would like to introduce some basic knowledge of variable optical attenuator in this blog.

what is Variable Optical Attenuator?

Variable Optical Attenuator (VOA) is a double window (1310/1550nm) of passive optical components. Variable optical attenuator could continually and variably attenuate the light intensity in the optical fiber transmission. Variable optical attenuator cable could help simulate distance or actual attenuation in the fiber optic testing work by inserting a calibrated attenuation into the link. By using the variable optical attenuator (VOA), technicians could verify the power margin received by testing the fiber optic link power budget. Fiber optic VOA can help the user vary the light power injected from a light source into the optical fiber.

VOA type

Principle of Variable Optical Attenuator

The power reduction is done by such means as absorption, reflection, diffusion, scattering, deflection, diffraction, and dispersion, etc. Variable optical attenuator usually works by absorbing the light, like sunglasses absorb the extra light energy. It typically gets a working wavelength range in which they absorb the light energy equally. They should not reflect the light since that could cause unwanted back reflection in the fiber system. Or by scattering the light such as an air gap. Another type of attenuator utilizes a length of high-loss optical fiber. It operates upon its input optical signal power level in such a way that its output signal power level is less than the input level.

Built-in Variable Optical Attenuator

Variable optical attenuator may be either manually or electrically controlled. A manual device is useful for one-time set up a system, and is a near-equivalent to a fixed attenuator, and may be referred to as an “adjustable attenuator”. In contrast, an electrically controlled attenuator can provide adaptive power optimization.

Attributes of merit for electrically controlled devices, include speed of response and avoiding degradation of the transmitted signal. Dynamic range is usually quite restricted, and power feedback may mean that long term stability is a relatively minor issue. Speed of response is a particularly major issue in dynamically reconfigurable systems, where a delay of one millionth of a second can be expected to result in the loss of large amounts of transmitted data. Typical technologies employed for high speed response include LCD, or Lithium niobate devices.

With this blog, we have learnt the basic knowledge of variable optical attenuator.  It is necessary to use in fiber optical communications. Fiberstore is a professional supplier of fiber optic communication solution. Variable optical attenuator is just one of PON(passive optical network) components. For more information about variable optical attenuator, welcome to visit our website or contact us over

The Process Of FTTH Network From 2011 To 2013

FiberStore news, the Chinese traditional fiber optic connector manufacturers not fared well in 2013, according to statistics, in the first quarter shipments of fiber optic connectors for FTTH “cold junction” decreased nearly 80% compared to 2012, which is regarded as technical magic for rapid deployment of FTTH by operators, gradually fell out of favor.

In the FTTH project, inevitably need to connect 5-7 fiber breakpoint. Before the advent of FTTH, fiber is mainly used for the backbone network, the breakpoints are using fusion splicer to connect, but because of its fusion splicer bulky, expensive, difficult to master the technology, these characteristics make it does not apply to FTTH project fast, low cost, convenience requirements.

Therefore, a few years ago, the industry developed fast connector, simple, convenient and low cost of FTTH splice junction, called the cold welding technology. United States, Japan, South Korea, which are the earliest development scale of FFTH, all have used the cold welding technology, verify the maturity of this technology.

“Hot melt” Return

In 2011, China Telecom launched the “city network” strategy, start the FTTH large-scale construction of China, and follow the international operators used cold welding technology. For a time, Chinese fast connector market raised quickly.

In the second half of 2011, cold welding technology began a large-scale unsuitable. The cold welding industrial chain which lacked details exposed its shortcomings: Although the same shape, but the heart technology of slot technology and matching fluid were unable to mark the international technology, below standard connectors entered into the network, caused massive FTTH quality problems.

In 2012, the three big operators reflected on this, Wei Leping, China Telecom Science and Technology Committee, noted: “FTTH network with serious quality problems, the network Splice, splitters and other products need to strengthen quality inspection.” But the problem was not changed with the operator’s attention. At present, in addition to Shanghai and Jiangsu, FTTH from other provinces still have serious quality problems.

However, it also provides an opportunity for some vendors. Fusion Splicers with “Miniaturization, long battery life, low cost, easy to operate” characters became hot topics in research and development.

Google Fiber is Aiming to Breakout the U.S Telecommunication Duopoly Market

Google Fiber is Aiming to Breakout the U.S Telecommunication Duopoly Market FiberStore News, According to the foreign media reports, since its inception, Google Fiberis basically regarded as an experiment in the industry, aiming to highlight the poor performance of the network service providers to promote high-speed broadband services, which is also test platform of next generation of advertising and video technology. Google has been working to correct this stereotypes of people, and repeatedly stressed that it is their serious business to carry out, even if there are indications that they would never in a nationwide promotion of Google Fiber (only a handful of cities deployment)

Media reports fully proved Google is by trying to get people to think more seriously about Google’s fiber optic network project to get it regarded as a major broadband company, although not always the case. Technology News clearly states: This network was initially seen as what the Internet giant used to test its news services and advertising model as an experiment network. Others also would like to know if Google network is just is a mean to promote the existing cable TV and phone companies to provide faster Internet service. Obviously, it was agreed that Google as a rich and powerful technology giant is affordable with this project and simply credited the cost as research and development expenditures.
The reason of Google fiber networks impress on peoples in this way is because that is the truth. This makes Google recently announced the entry into Austin and Prove does not really change that. Google Fiber is an amazing little experiment, although it may ultimately have a huge impact, it is till a long time for it to get rid of “the interesting experiment” (in issues on the U.S market capacity background and connectively)
It is not important that how we call it. Google Fiber MiloMeldin (formerly known as @Home) participate in the association meeting on FTTH in North America this week, and reiterated Google fiber network is a serious money-making initiatives. During the meeting, other than repeatedly requesting for subsidies, deregulation or complaining the poor service (just like the attitude of telecommunication industry’s mobile operators towards the large carries), Google in turns insisted that the earnings of working with the local government is rather abundance.
To be specifically, Google requires Kansas City as the assigned inspector for the Google Fiber project construction to enable speedy completion of the city’s periodic inspection, which will further saves the time and money that Google invest I the construction phase. This company also requires deploy fiber in other cities’ piping, and minimizing the unnecessary street excavation projects. The company has cooperated with the public utility companies to get the supported base station location for connections of the new fiber optic network.
Despite all these sound very good, but as of now, Google has not disclosed any convincing financial data, and Google Fiber has not yet been deployed on a large scale in families except a few part families. Although it is welcomed that Google Fiber intended to break the duopoly U.S telecommunication market, it is still a long way to go if it let people to see it as a real player in the market and a truly disruptive market forces.

FTTH Promote The Surge In Demand For Optical Network Testing

Testing is an important means to enhance network quality, network construction, an important means of operators. Test on the one hand, to ensure the consistency and stability of the business, at the same time can be effectively promoted the maturity of the industry.

Currently, the test is not only limited to test network equipment, more and more important for the business and user perception test. Therefore, testing techniques, testing tools developed laboratory environment to build all aspects of test quality assurance will affect the results of the entire test.

In the field of fiber optic communications, with China Mobile completed 100G network test now, “Broadband China” strategy forthcoming FTTH being the country vigorously. Fiber optic communication testing methods and techniques are changed with the change of network.

FTTH test can be roughly divided into the construction, maintenance, fault diagnosis phases. FTTH three wavelengths (1310nm, 1490 nm and 1550 nm) loss during the construction phase, the test focus. The optical splitter in a PON will bring a larger loss (such as a 1:32 optical splitter loss will be greater than 15dB), not only makes the light generating loss downlink, the uplink of the light will produce substantially the same loss. Splitter implementation techniques vary, making each optical path loss may exist differences, in order to strictly limit each optical path loss within the budget is a challenge.

Optical return loss is one of the difficulties of the current test. Optical return loss is not only a loss of energy, but also lead to the originator laser instability. Recommendations based on the ITU-TG.983 and G.984 series, optical return loss values should be in both directions. PON-based FTTH OTDR put forward new demands, requires not only support the 1490nm wavelength testing, but also with penetrating optical splitter. In addition, FTTH network transmission distance is shorter, but the introduction of the high loss of optical splitter requirements OTDR dynamic range wide enough selection of shorter OTDR dead; joints more requirements, high linearity.

In large-scale FTTH deployment phase, testing will be very heavy instrument automation has become one of the factors to be considered. FiberStore’s FOT-930 test instrument developed for this demand, the user simply one-button operation can be completed in the 10s three wavelengths (1310nm, 1490 nm and 1550 nm) bi-directional loss, optical return loss and fiber length test and automatically store test results.

Activation and maintenance, fault diagnosis stage, the most commonly used test instruments PON power meter. EPON or GPON system using time division multiple access technology, OLT and ONT need to activate in order to work, PON power meter has to trigger tests optical power capacity and support meter needs different optimization. FTTH construction early will also face business opened the challenges, many links need to manually construction service activation, as well as the opening of a long cycle, poor customer perception. Troubleshooting link, the failure rate and the declaration of DSL-more than twice the proportion of regional centers for processing, the door-to-door high.

FiberStore, EXFO, JDSU and other enterprises to provide FTTH is simple, fast, and a variety of intelligent solutions, provide strong support for FTTH construction.