Fiber Optic Attenuators—Types And Applications

A fiber optical attenuator is a fiber-coupled device used to reduce or balance the power (the power level of an optical signal, either in free space or in an optical fiber) of the light transmitted from one device to another device. Fiber optic attenuators are designed to use with various kinds of fiber optic connectors. The basical types of optical attenuators are fixed, step-wise variable, and variable fiber optic attenuator. Insertion loss and return loss, or back reflection, are collectively referred to as attenuation; total attenuation is called system loss.

Fiber Optic Attenuators provide technicians with a means of adjusting an optical signal level. Attenuators are commonly used in fiber optic communications, either to test power level margins by temporarily adding a calibrated amount of signal loss, or installed permanently to properly match transmitter and receiver levels.

Commonly used fiber optic attenuators are the female to male type, which is also called a plug fiber attenuator. Plug fiber attenuators utilize male/female ceramic ferrule connectors. Fixed value attenuators function at one loss level, while variable attenuators like the variable optical attenuated jumper (VOA) can adjust loss in a range, as by a turning screw. Patch cord attenuators are fibers that combine the functions of the patch cord and attenuator, reducing costs.

Types of fiber optic attenuators:
1. Female to male plug style optical attenuator (MU, SC, FC, ST, LC) PC& APC polish available;
2. Flange style fiber optical attenuator;
3. Adjustable fiber optical attenuator (FC style) Attenuation scale:0~30dB;
4. IN-Line style fiber optical attenuator.

Wide range variable & inline fiber optic attenuator
The inline fiber optic attenuators are with more accurate attenuation compared with traditional connector type fiber optic attenuators. What is more, the fiber optic attenuator is with a precision screw set, by turing it, the attenuation range can be varied. And this fiber optical attenuator can be with various terminations on the each side of the cable.

Variable Fiber Optic Attenuators
Fixed value fiber optic attenuators can reduce the power of fiber light at a fixed value loss, for example, a 10dB SC fiber optic attenuator will reduce the optical power 10dB and utilize a SC male to female attenuator. Variable fiber optic attenuators (or adjustable fiber optic attenuator) are with adjustable attenuation range. It usually is inline type, the appearance like fiber optic patch cord; it is with an adjustable component in the middle of the device to change the attenuation level to a certain figure. There are also handheld variable fiber optic attenuators; they are used as test equipment, and we have the inline fiber optic attenuators.

Fiber optic attenuator name is based on the connector type (like lc attenuator) and the attenuation level. For example, LC 5dB fiber optic attenuator means this attenuator use LC fiber optic connector and it can reduce the optical fiber power level by 5dB. Commonly used attenuation range is from 1dB to 20Db. Fiber Optic Attenuators are employed in telecommunications networks, local area networks (LAN), and cable television (CATV) systems. They also can be used in fiber optic sensors, testing instruments, and fiber to the home. Compact, environmentally sound, and suffering low return losses, these devices can be embedded into optical fiber networks fitted to the wide variety of industry standard connectors and fibers.

What are Fiber Optic Transceivers Used for

Fiber optic transceiver is also called fiber optic transmitter and receiver. It is composed by optoelectronic devices, the functional circuit and the optica interface. the optoelectronic device includes a transmitter and receiver.

Fiber Optic Transmitters: LEDs, fabry-perot (FP) lasers, distributed feedback (DFB) lasers and vertical cavity surface-emitting lasers (VCSELs) are the 4 types of source for the transmitters that can convert the electrical signals into optical signals. They are al tiny semiconductor chips. Fiber Optic Receivers: The receivers use semiconductor detectors (photodiodes or photodetectors) to
convert optical signals to electrical signals. Silicon photodiodes are used for short wavelength links (650 for POF and 850 for glass MM fiber). Long wavelength systems usually use InGaAs (indium gallium arsenide) detectors as they have lower noise than germanium which allows for more sensitive receivers. Very high speed systems sometimes use avalanche photodiodes (APDs) that are biased at high voltage to create gain in the photodiode.

The role of fiber optic transceiver can be simply concluded: Fiber transceiver is a photoelectric conversion device that converting electrical signal into an optical signal at the transmission side, after the transmission on the fiber optics, the optical signals are transmitted into electrical signals at the receiving side.

In the traditional network, the network cables or coaxial cables are usually used, but their communication bandwidth and signal quality they provide can no longer meet the growing need of customers. While the era of fiber optic network makes the optical switches, SDH equipment, fiber converters, fiber optic multiplexers, and more related fiber optic equipment developed rapidly. In
the works process of these fiber optic network equipments, the fiber optic transceiver modules are needed to convert the electrical signals via the laser driver to optical ones, and then transmit
the optical signals trough the optical fibers for a long distance, when the signals arrive at the receiving end, it then be converted into an electrical signals through the fiber optic receiver ((Pin-Tia or APD).

The following list the regular equipments that the fiber transceivers may used for:
Fiber Optic Multiplexer: Common fiber optic multiplexers use 1 x 9 package fiber optic module, some HD multiplexers would use SFP optical modules.
Fiber Optic Converters: 1 x 9 transceiver modules.
Fiber optic network card: 1 x 9, SFP or SFP+ optical modules.
Fiber-optic high-speed ball machine: SFP optical module
The base station: XFP, SFP optical module.

The above is the analysis of several devices using the optical modules. It can be seen that 1 x 9 and SFP optical modules are the most commonly used, the difference between them is that:
1 * 9 optical module are welded on the device, while SFP transceiver is hot-swappable.

There are uniform standards for the design and production of fiber optic transceivers. The case of the basic specifications, the optical modules from the major manufacturers such as Huawei, Cisco, Juniper, FiberStore, etc. In addition, the compatibility issues that we often talk about refers to the optical modules are compatible use for communications equipment of different manufacturers, for example, the optical module from FiberStore can be totally compatible with Cisco routers or switches. Because the fiber modules are written with the Cisco series switches compatible codes during the production to be work normally with Cisco equipments.

Fiber Testers Of Fusion Splicer

fusion splicer is a device that uses source of heat to melt two optical fibers together at their end faces, to form a single long fiber. The resulting joint, or fusion splice, permanently joins the two optical fibers end to end, so that optical light signals can pass from one fiber into the other with very little loss. The source of heat is usually an electric arc, but can also be a laser, or a gas flame, or a tungsten filament through which current is passed.

Features of Fusion Splicers:
Carefully engineered fiber clamps allow the precise fixing of the fiber ends. At least one clamp is precisely adjustable with micrometer screws;
For splicing polarization-maintaining fibers, it is also necessary to rotate one of the fibers around its axis;
A microscope allows inspection of quality and alignment of the fiber ends. Often, there is a knob for switching between two orthogonal directions of view. The fiber cores can also usually be seen;
A “prefuse”, applied without touching the fibers, allows one to clean the surfaces;
Some splicers do the alignment automatically based on a camera image and/or on monitoring the optical power throughput. For the latter, there must be a light source attached to one fiber end, and a photodetector for the other one;
Some devices can also measure the quality of the resulting splice.

The process of Fusion Splicing involves using localized heat to melt or fuse the ends of two optical fibers together. The Splicing process begins by preparing each Fiber end for fusion. Fusion splicing requires that all protective coatings be removed from the ends of each fiber. The fiber is then cleaved using the score-and-break method. The quality of each fiber end is inspected using a microscope. In fusion splicing, Splice Loss is a direct function of the angles and quality of the two fiber-end faces.

Before optical fibers can be successfully fusion-spliced, they need to be carefully stripped of their outer jackets and polymer coating, thoroughly cleaned, and then precisely cleaved to form smooth, perpendicular end faces. Once all of this has been completed, each fiber is placed into a holder in the splicer’s enclosure.

Cleaning the splicing device and the fiber
Since the slightest trace of dust or other impurities can wreak havoc on a splice’s ability to transmit optical signals, you can never be too clean when it comes to fusion splicing. Even though fibers are hand-cleaned before being inserted into the splicing device, many fusion splicers incorporate an extra precautionary cleaning step into the process: prior to fusing, they generate a small spark between the fiber ends to burn off any remaining dust or moisture.

The fiber is then cleaved using the score-and-break method so that its endface is perfectly flat and perpendicular to the axis of the fiber. The quality of each fiber end is inspected using a microscope. In fusion splicing, splice loss is a direct function of the angles and quality of the two fiber-end faces. The closer to 90 degrees the cleave angle is the lower optical loss the splice will yield.

Splicing Optic Fiber
The splicer emits a second, larger spark that melts the optical fiber end faces without causing the fibers’ cladding and molten glass core to run together. The melted fiber tips are then joined together, forming the final fusion splice. Estimated splice-loss tests are then performed, with most fiber fusion splices showing a typical optical loss of 0.1 dB or less.

Fiberstore is the recognized leader in the development of the highest quality fusion splicing equipment and accessories that have and continue to advance fusion splicing technology. You have a wide selection of fiber optic splicing relevant equipments, like fusion splicer, fiber optic cleaver, fiber cleaver blades, fusion splicer assemblies, etc.

The Standard Of Fiber Optic Transceivers

Fiber optic transceivers are transmitter/receiver modules that are pre-packaged in a standardized form. They offer convenience and the low cost of mass production, are widely used in backbone networks and access networks to support Internet services and enterprise applications that require broadband transmission.

In the fiber optic field, ITU-T is mainly responsible for procedures and IEC is mainly responsible for products. Although these organizations cooperate, they remain separate and were established with different objectives, so some products and procedures, such as optical fibers, must be specified in each organization. Therefore, the two organizations cooperate to avoid producing conflicting specifications.

A standardized fiber optic transceiver is adapted to provide an optimal PCIe expansion over a fiber optic medium. Signal buffers are utilized to translate and fine-tune standardized PCIe traffic to a level of low voltage differential signaling (LVDS) that is comprehensible to a wide range of fiber optic transceivers over a wide range of interface bandwidths. The intended use for such a high-speed LVDS buffer is to strengthen and enable PCIe signals over metal (copper) cable or metal printed circuit board (PCB) traces for large PCBs, such as backplanes, server motherboards, etc. By disposing the PCIe buffer used for metal (copper) cable between the PCIe bus and the fiber optic transceiver, one can achieve the signal conditioning and translating required to allow PCIe signals to pass over the fiber optic medium.

The SFP transceiver is not standardized by any official standards body, but rather 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 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.

Fiber Optic Transceiver design issues nowadays include the following:
Low cost;
High data-rate;
Mechanical compatibility of connector interfaces;
Cross-talk between transmitter and receiver electronics;
Electronic noise (EMI) issues, both with respect to emissions and susceptibility;
Ease of manufacture (i.e. manufacturability);
Minimal footprint.

With the potential for providing high-speed and broadband characteristics, research and development of technologies related to fiber optic transceivers started. As a result of these demands and applications that require high-speed data transmission, new issues have arisen related to delay in the electrical connection network and physical wiring space in and between equipment. In order to deal with these issues, standardization activities for optical circuit boards and sc/apc fiber connectors for circuit board attachment have started in TC91 (Electronic assembly technology).

Economical Fiber Media Converter To Long Distance Transmission

Fiber media converter, also known as fiber transceiver or Ethernet media converter, is a simple networking device which receives data signals, sents via one media, converts the signals and then transmits the signals into another kind of media. A fiber optic media converter makes it possible to connect two dissimilar media types with fiber optic cabling, can transform between different media, different cable types and different equipment interfaces. They were introduced to the industry nearly two decades ago, and are important in interconnecting fiber optic cabling-based systems with existing copper-based and structured cabling systems.

Key Features
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. 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.

Fiber media converters are also used in metropolitan area network (MAN) access and data transport services to enterprise customers. When expanding the reach of the LAN to span multiple locations, fiber transceivers are useful in connecting multiple LANs to form one large campus area network that spans over a wide geographic area.

Types
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.

There are singlemode converters (also called WDM fiber optic converters) and multimode converters. For singlemode converters, there are dual fiber type and single fiber type which the fiber cable functions both as transmitting media and receiving media. While for multimode converters, there are only dual fiber types. Working distance is also different. For typical multimode fiber optic converters, their working distance max is about 2km, for single mode fiber media converters, their working distance can be 20km, 40km, 60km, 80km and up to 120km.

Some fiber optic converters will work with any type of Ethernet cable while others only have ports for either the 100 Megabit or the 10 Gigabit speed Ethernet cables. Different brands and models of converters have different speed caps.

Benefits
Fiber media converter protects your investment in existing copper Ethernet-based network, is an economical solution to achieve long distance transmission based on current status. With the rapid development of society, the transmission of different types of information, like audio, video and data, has become more and more important and Ethernet has been a good way to deal with this need. Traditional Ethernet fiber converter has its disadvantages because it use copper wires and its working distance is very short (about 100meters). Fiber media converter is the solution of this problem, it could extend the Ethernet working distance to max 100km or more, what is more ,the fiber optical converter used today is cheap and reliable.