Category Archives: Optical Attenuator

Guide To Fibre Optic Attenuator

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Optical Fibre Attenuator is a device to reduce the optical fibre power at a certain level by a predetermined factor. The intensity of the signal is described in decibels (dB) over a specific distance the signal travels. Attenuator provides a certain amount of isolation between instruments, thus reducing measurement interaction. This can be done by attenuating the unwanted reflected signal due to imperfect matching. Fibre optic attenuators are used in applications where the optical signal is too strong and needs to be reduced, it is mainly used for fibre optic system of measurement, signal attenuation for short distance communication system and system test, etc. For example, in a multi-wavelength fibre optic system, you need to equalize the optical channel strength so that all the channels have similar power levels. This means to reduce stronger channels’ powers to match lower power channels.

The basic types of optical attenuators are fixed and Fibre Optic Variable Attenuator. The most commonly used type is female to male plug type fibre optic attenuator, it has the fibre connector at one side and the other side is a female type fibre optic adapter. Female to male mechanical attenuator is assembled with a fixed type connector, so it can only be connected with one patch cord, such as LC Attenuator, sc Attenuator, fc Attenuator, st Attenuator, etc.

Fixed Attenuators

Fixed value attenuators have fixed values that are specified in decibels. Just its name implies, fixed value attenuator’s attenuation value cannot be varied. The attenuation is expressed in dB. The operating wavelength for optic attenuators should be specified for the rated attenuation, because optic attenuation of a material varies with wavelength. Their applications consist of telecommunication networks, optic fibre test facility, Local Area Network(Lan) and Catv systems.

Fixed value attenuators are composed of two big groups: In-line type and connector type. In-line type looks like a plain fibre patch cable; it has a fibre cable terminated with two connectors which you can specify types. The in-line fibre optic attenuator is fit to use with optical patch cables. To use these in-line Fibre Optics Attenuators just select the connector type you need ST, SC, LC, & FC Available, the Polish (PC, UPC or APC angled Polish) & the Decibel dB rating.

Variable Attenuators

Variable attenuators come with variety separate designs. They are normal used for testing and measurement, but they also have a wide usage in Edfas for equalizing the light power among separate channels. One type of changeable attenuator is built on a D-shaped fibre as a type of evanescent field device. If a bulk external material, whose refractive index is greater than the mode effective index, replaces a part of the evanescent field reachable cladding, the mode can come to be leaky and some of the optic power can be radiated. If the index of the external material can be changed with a controllable mean, straight through the effects such as thermo-optic, electro-optic, or acoustic-optic, a gadget with controllable attenuation is achievable. Other types of variable attenuators consist of air gap, clip-on, 3-step and more.

As it comes to getting a fibre optic attenuator you have several options listed above, so before you buy one you must be sure at what level you want to attenuate your signal and then choose what type will work best for you. Taking the time to choose the right one can save you big time.

Understanding Optical Attenuators

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Fibre optic attenuator is used to reduce the power level of optical signal, either in free space or in an optical fibre. They are often used in optical communication systems where the optical signal is too strong and needs to be reduced, in which the attenuation, also called transmission loss, helps with the long-distance transmission of digital signals.

Optical attenuators can take a number of different forms and are typically classified as fixed or variable attenuators. Fixed attenuators can be broken down into either build out style or incorporated into a patch cord. The build out variety is a small (~ 1.25 inch long) attenuator with a male connector interface on one end and a female interface connector on the opposite end. The build out style is typically fabricated with either air gap attenuation or doped fibre attenuation.

Fibre optic attenuators can be designed to use with various types of fibre optic connectors. Commonly used fibre optic attenuators are the female to male type, which is also called a plug fibre attenuator. Another type inline fibre optic attenuator is designed with a piece of fibre optic cable at any length and connectors are installed as the customers request. Fixed value fibre optic attenuators can reduce the optical light power at a fixed level, for example, a 10dB SC fibre optic attenuator will reduce the optical power 10dB and utilize a SC male to female attenuator. Variable fibre optic attenuators are with adjustable attenuation range. There are also attenuation fibre optic patch cables available, their function is the same as attenuators and are used inline.

Variable Attenuator (or ajustable fibre optic attenuator) is a need to provide different under construction decline. The reduction of precision devices for a wide variety of fibre optic transmission lines to carry out scheduled, the amount of light intensity attenuation. There are also handheld variable fibre optic attenuators which are used as test equipment.

Typical attenuation values are between 3 and 20 dB. It is used in optical systems where the optical power from a source is too high for the test equipment in use. Fixed plug type fibre attenuator provides a connector plug (male) and an adapter socket (female) to connect between fibre patch cord and fibre adapter. Fixed plug type optical attenuator introduces an in-line fixed loss that will reduce the source power to an acceptable detection level. The attenuation level should be stable with temperature and wavelength for a stable reliable system.

An optical attenuator uses a segment of attenuating fibre interposed in the optical path. The attenuating fibre is produced by using a solution doping technique to introduce transition or rare earth elements into the fibre’s core. The dopant reduces the transmission of the fibre. The degree of attenuation depends upon the material used as the dopant, the dopant level, and the length of the attenuation segment. In a specific embodiment, an optical attenuator is provided having a first and second signal carrying optical fibres and an attenuating fibre segment, each of which has a core, a cladding substantially coaxial with the core, and a substantially planar end face. The attenuating fibre segment is fusion spliced between the first and second signal carrying optical fibres. In a second embodiment a portion of the cladding of the attenuating fibre is chemically etched.

Wide range variable & inline fibre optic attenuator and the inline fibre optic attenuator are with more accurate attenuation compared with traditional connector type fibre optic attenuators. Variable optical attenuators from FiberStore are specifically designed for use in DWDM networks with individual channel source elements such as add drop multiplexer.