Low Water peak LWP Optical Fiber: a new optical fiber design of up to 2.5 Gb/s

Today's communication networks are composed of multiple interconnected optical and electrical components to support high-speed video, voice, and data transmission. The backbone of the network is optical fiber. Its design and manufacture are used to optimize attenuation and dispersion, making the network the most cost-effective and cost-effective network. A new optical fiber design is widely accepted in the global communication industry, that is, low water peak LWP) optical fiber. The low water peak Optical Fiber minimizes the attenuation of the entire Standard Single-mode transmission window 1260nm-1625nm. This allows the carrier's transmission engineers to make extra choices to increase the total bandwidth of the optical fiber and the transmission distance of the network system. For cable TV applications, this kind of optical fiber selection can generate additional revenue opportunities, especially with emerging technologies such as coarse Wavelength Division Multiplexing (CWDM) and other low-cost electronic devices. It has the potential to enable future upgrades for fiber-optic coaxial cable hybrid network (HFCs) systems, Passive Optical Networks, fiber-to-households, and/or roadside.

Wavelength Division Multiplexing

As new cable TV technologies are emerging, cable TV providers must meet the needs of increasing bandwidth in the network. From the beginning to the center, the bandwidth needs have been resolved by intensive Wavelength Division Multiplexing (CWDM. Recently, the cable TV supplier's system structure has been transferred from the basic system head end to the central single channel to the multi-channel system. In order to meet the demand for increasing network bandwidth, providers must continue to push Wavelength Division Multiplexing more deeply into the system. Due to the large upfront investment in Dense Wavelength Division Multiplexing and related devices, it is an expensive choice. The rise of coarse Wavelength Division Multiplexing CWDM evolved from Dense Wavelength Division Multiplexing satisfies this need. CWDM uses a wide channel interval of approximately 20 nm in the whole wavelength spectrum ). Therefore, 16 or more channels can be reused on a single optical fiber, which becomes a major factor in improving the bandwidth of a single optical fiber.

Coarse Wavelength Division Multiplexing-economic value

CWDM increases the wavelength spacing for multiple service providers (MSO) to provide a cost-effective solution for network expansion. Cost savings can be achieved by reducing the cost of light sources, multiplexing, and demultiplexing brought about by increasing the wavelength spacing. System vendors provide a comprehensive cost-effective solution by providing easy-to-produce, highly efficient, non-cooled direct-tuning lasers. CWDM equipment requires less energy consumption and less space because there is no cooling Laser, thus saving the cost of building data centers and nodes. Lower cost per channel becomes a value point that is advantageous to MSO.

Application of coarse wavelength division multiplexing and low water peak Optical Fiber

A typical MSO network consists of a standard single-mode optical fiber. It is not optimized for a growing full-spectrum CWDM network. Today's standard single-mode optical fiber is optimized for 1310nm transmission, and it also has the ability to transmit at 1550nm. However, most of them lose the linear spectrum due to the attenuation of the "water peak" area near 1383nm. Till now this zone still does not apply to any wavelength transmission, mainly because its attenuation is larger than 1310nm. Therefore, a standard single-mode optical fiber can provide up to 12 CWDM channels. In the best case, even in a 16-channel system, the standard single-mode optical fiber is subject to attenuation and distance.

By eliminating high attenuation within and near the water peak, the transmission of low water peak optical fiber in this area provides the potential. This optical fiber has a smooth attenuation curve that enables transmission between 1260 to nm in the entire Single-Mode working window. A 16-channel CWDM/LWP optical fiber link is probably subject to attenuation due to the high attenuation between 1290nm-1310nm. Therefore, it can be conservatively assumed that the attenuation of the link where the low water peak optical fiber is used is approximately 0.35dB/km.

If a standard single-mode optical fiber is used, the high attenuation between 1370nm-1390nm makes the transmission link subject to attenuation. Conservatively estimated that the channel will have an attenuation value of 0.5-DB/km. Assuming the budget for a 20 dB link, the low-peak optical fiber has a link transmission distance of 57 kilometers, while the Standard Single-Mode Optical Fiber only has a link transmission distance of 33 kilometers. Because the average distance of most point-to-point systems is between 20 km and 50 km, low water peak optical fiber can be the main factor to optimize the CWDM system. Compared with standard single-mode optical fiber, the low-water peak optical fiber can be extended from 1360nm to 1460nm in the E band) the additional transmission capability enables it to increase the wavelength spectrum by 50%, increase the channel transmission by 33%, and increase the transmission distance by about 70%.

Fiber-to-user

Catv mso, a cable TV service operator using a fiber-optic coaxial cable hybrid network (HFCs), is currently in the optimal position to provide fiber-to-household FTTH solutions for its customers compared with other telecom service providers. They are more advanced to users through the structure of the hfc-based system. Optimistically, MSO can place nodes closer to users and ultimately place nodes at residential locations-this is an FTTH solution, which must be prepared through physical devices.

Due to the different MSO, physical structures and electronic devices, the nodes of the HPC network usually provide services for-residents. Generally, they lay fiber cables with a maximum distance of-meters from the user. In this general-purpose system, MSO has many options to provide users with FTTH solutions. One of the special solutions is the use of low water peak LWP) optical fiber dedicated Optical Fiber solution.

The dedicated Optical Fiber solution is a solution with abundant optical fiber and passive optical network. Its structure ensures that the user has a dedicated optical fiber to the node, which is similar to connecting the hub or the head end to the node with the optical fiber. Although it is a relatively expensive solution compared with the optical splitter system, it provides almost unlimited bandwidth and is very easy to upgrade. The dedicated Optical Fiber solution requires a large number of active optical devices in the entire network, because in essence, its nodes become the hub and users' homes become nodes. Electronic devices are required for transmission at each location. The distance of Optical Fiber Transmission determines the type and cost of these devices.

A new technology called triplicate triplexer) will make this option possible and keep costs quite low. The concept of triple multiplexing is that each household optical fiber processes two downstream signals and one upstream signal to provide video, voice, and data services. Triplicate consists of two receivers, namely a 1550nm analog video bandwidth, around 1.5 μm data, and a speech bandwidth. The 1.3 μm transmitter is associated with the hub/head end.

A potential disadvantage, especially for the increasing video service industry and its relatively high-speed transmission) is that the high power of analog signals may cause interference to 1.5 μm signals. Some solutions are to move the channel to a channel close to 1.3 μm, that is, the typical 1460nm-1490nm region. When it is accepted by conventional single-mode optical fiber in the high attenuation zone of 1383nm, the channel will be subject to attenuation, which leads to a new problem. Low Water peak LWP) optical fiber can solve the problem of keeping the 1.5 μm channel away from The 1.55 μm channel and does not accept the attenuation limit. Therefore, FTTH and LWP optical fiber and triple multiplexing applications can provide the maximum transmission distance and the most effective utilization potential of physical devices.

Conclusion

For MSO applications with a link distance of 30-50 km and a data rate of up to 2.5 Gb/s, LWP is the most ideal optical fiber. Coarse Wavelength Division Multiplexing (CWDM) and low water peak LWP) optical fiber can provide a way for future upgrades of the fiber coaxial cable hybrid network system, passive optical network, and fiber-to-user and/or roadside. Low Water peak LWP) optical fiber can provide flexibility and diversity of network design, it can make full use of the entire transmission window. The combination of low water peak LWP and coarse Wavelength Division Multiplexing (CWDM) results in greater transmission capacity, increased system flexibility, maximum transmission distance, and reduced network costs.

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