A fiber attenuator also called optical attenuator, is a device used to minimize the level of an optical power signal in an optical fiber network for various purpose. Optical attenuators are regularly used in fiber optic communications, to test power level limits and for the time being adding an adjusted amount of signal loss, they are also used to install it forever to accurately match transmitter and receiver sensitivity levels. If a received signal power level is too high, a temporary solution is to wrap the cable around a pencil or a similar object until the required level of attenuation is reached. Severe bends stress optic fibers and can cause losses of light travelled inside these. Though, such solutions are unpredictable, as the stressed fiber be likely to to break over time.
The power lessening is completed by such means as absorption, scattering, diffusion, deflection, reflection, diffraction, and dispersion, etc. Optical attenuators typically work by absorbing the light, like sunglasses absorb extra light energy. They usually have a working wavelength range in which they absorb all the light energy. An optical attenuator should not scatter or reflect the light in an air gap, as that could cause undesirable back reflection in the fiber. A different type of attenuator exploits a length of an optical fiber with high-loss, that type of attenuator functions upon its input optical signal power level in such a way that its output signal power level is less than the input level.
Optical attenuators can take different arrangements and are normally classified as fixed or variable attenuators.
Fixed optical attenuators used in fiber optic network may use a diversity of rules for their operation. Desired attenuators use material among misaligned splices, or doped-fibers, or total power as both of these are dependable and low-priced. In-line type of attenuators are combined into patch cables. The alternate build-out style attenuator is a small male-female adapter that can be added onto other cables.
Non-preferred attenuators frequently use gap loss or reflective principles. Such devices can be sensitive to: wavelength, modal distribution, impurity, temperature, vibration, may cause back reflections, may cause signal dispersion etc.
Loopback fiber optic attenuator is intended for testing, engineering and the burn-in phase of boards or other equipment. Offered in LC/UPC, LC/APC, SC/UPC, SC/APC, MTRJ and MPO for single mode application.
Built-in variable attenuators
Built-in variable optical attenuators, might be electrically controlled or manually controlled, depending upon type. An electrically controlled attenuator can deliver adaptive power optimization. As compared to an automatic, a manually controlled attenuator is useful for one time set up of a system, and is almost alike to a fixed attenuator, and may be stated to as a variable attenuator.
Variable optical test attenuators
Variable optical test attenuators commonly use an adjustable neutral density filter. Regardless of comparatively high price, this type has the benefits of being constant, wavelength insensitive, mode insensitive, and proposing a large dynamic range. Other systems such as LCD, variable air gap etc. have been tried over the years, but with partial accomplishment. These types of attenuators may be manually or motor controlled. Motor control attenuators give regular users a different productivity advantage, since commonly used test sequences can be run automatically.
Attenuator tuning is a main concern. The user naturally would like a total port to port correction. Also, calibration should frequently be at different wavelengths and power levels, as the device is not all the time linear. Nevertheless, a number of tools do not in fact offer these basic features, apparently in an effort to decrease cost. The most precise variable attenuator devices have thousands of tuning points, resulting in excellent overall accuracy in use.