Active couplers require power to amplify signals, ideal for long distances, whereas passive couplers, power-free, split signals without amplification, suitable for short ranges.
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External Power Required
Active couplers require an external power source to work effectively and so are quite different from their passive counterparts. This is due to the fact that, inside the box, they contain electronic components that are specifically designed to boost an optical signal or otherwise manipulate it. This can be very useful for ensuring the that is broadcast along a long length of cable or in a high bandwidth application. For instance, a telecommunications unit may use an active coupler if the signal is being transmitted for several kilometers. In such a situation a power source might be used to amplify the signal in order to ensure that it does not with by the time it reaches the other end.
For example, if 100 kilometers of data is being transmitted and passive couplers are being used, then the entirety of the signal’s power might be lost halfway through. Typically, passive couplers lose approximately 0.2 to 0.3 dB of strength for every kilometer. Consequently in this example, the signal would experience a total attenuation of 20 to 30 dB. An active coupler could include a signal amplifier to ensure that the signal does not lose power. This would mean that when the signal is finally broadcast at the end, it is a 17 dB stronger than when it was received. In such a way, the signal is boosted slightly at every point of transmission to ensure that it remains intact, and this is something that only active couplers can guarantee.
However, this additional capability is expensive, both to install and run. Not only is the active coupler unit double the price of its passive counterpart, but the power source makes it expensive to run over time. For instance, a unit may cost $200 and require $50 of power for every 5 years of use. Finally, owners of active couplers must also consider the matter of size and life span. Specifically, having a power source and electronic components living inside the unit require a larger overall unit in the case of active couplers. In addition, these components mean that active couplers have a much shorter lifespan than passive ones, which can manage with only the optical properties of glass and are more structurally sound.
Types and Applications
Active and passive couplers are different devices that perform specific functions in optical networks. As such, they differ in their respective design and application types, as certain couplers are better suited for specific applications for a variety of reasons. Passive couplers such as fused biconical taper and planar lightwave circuit are common devices used in fiber optic communication due to their simplicity and reliability.
Fused biconical taper couplers are popular as they can be adjusted by the manufacturer during the making for a specific splitting ratio. Planar lightwave circuits tend to be much smaller and typically exhibit excellent uniformity to split light into a dozen or even more outputs. As such, these simpler devices are often used in short-distance applications where signal loss does not affect performance over the run. In the context of a local area network, a planar lightwave circuit might split a data signal to a dozen separate offices, each located within 50 to 100 meters of the point of splitting.
Active couplers contain electronic components that allow them to adjust power and wavelength. They play a key role in long-haul fiber optic systems as they can be used to compensate for signal loss over hundreds or thousands of kilometers. This ability to amplify a signal is critical as the signal power drops over these long distances, with a signal power of approximately -2 dBm to -20 dBm after the signal has traveled over such long distances.
As such, active couplers can be used to amplify signals to facilitate intercontinental data links across the light spectrum that are used in transoceanic cables and similar infrastructure. Such couplers are also useful in network environments that would benefit from real-time control over the signal, such as boosting it to make up for an increased demand for bandwidth during peak traffic periods, including streaming services that require more data to stream in high definition.
Active couplers also have specific types of applications. First, these couplers find use in networks with long-distance runs, as such runs often need a way to adjust signal power. These couplers also see use in applications in which an active coupler can adjust the signal in real-time based on the volume of data and the state of the network. Next, these couplers are used in long-haul fiber optic systems where the signal must travel hundreds of kilometers without being significantly degraded. As such, an active coupler is expected to increase the power of any signal that passes through it.
Finally, a use for an active coupler is in a mid-range structure, such as a long local area network. In such a structure, the signal only needs to pass about 100 meters across several active couplers before reaching its destination; as such, it does not need a significant increase in power. Active couplers are much more expensive than passive devices: while a passive coupler might cost between $20 and $50, an active coupler might cost anywhere from $100 to $500. The higher price is due to the much more complex electronic setup used by active couplers. Active couplers also require a continuous supply of power and regular maintenance.
Performance
Generally, the performance of active and passive couplers differ to a significant degree, and mostly because of the difference in their operational mechanisms and application workflows in the context of fiber optics. Thus, passive couplers split optical signals without modifying their power. They do so by virtue of the intrinsic properties of the physical properties of optical fibers involved, including their refractive indices and the geometrical configuration.
This method works well in the case of short-haul communications – for example when the internet cable is used to deliver the signal within a single household or campus. A typical passive coupler is capable of splitting an incoming signal into the required number of outputs and does so as to divide the signal into the needed ratio. Usually, such a device would lose about 3.5 dB per split, and this level of signal loss is low enough for short-haul communications where the signal does not degrade too dramatically over a several meters-wide distance.
In turn, active couplers are able to boost the performance of the couplers by not only splitting the signal but also by amplifying it. Thus, active couplers are vital for long-haul fiber optic links between two cities or two countries. During such a long trip, signal strength could be dramatically degraded, and the active coupler would be able to compensate for it by raising the signal by 10 to 20 dB.
The case in point when it comes to active couplers is the functioning of submarine fiber optic cables. Current AI couplers allow users to browse the internet or make phone calls with some help of the coast-dwellers. The immense distance of such a cable makes it impossible to continue the work without amplifying the signal – even the most advanced passive coupler would see the data’s signal dwindle to zero on the continent, from which there may be namely this fiber cable to the continent it needs to reach.
The benefits of the passive couplers are the lack of power requirements, namely their energy efficiency, and low electric bill. The benefits of the active coupler is the unparalleled signal control, monitoring, and the ability to sue the fiber network on the next day after the cable broke rather than several months later. Overall, the decision to use one type of coupler over the other must be taken on account of different factors and parameters such as the application, budget, cable length, or the degrading signal that can cover thousands of locations on the way to its final destination in multiple large high-density city networks.
