Keywords: GPON, XGS-PON, CATV, CEx-WDM, FWDM
In an era characterized by efficient transmission and seamless evolution of fiber optic networks, wavelength division multiplexing (WDM) technology serves as a crucial factor in enhancing fiber resource utilization and enabling the coexistence of multiple services. Leveraging its technological expertise in optical communications, DFT's FWDM series and CEx-WDM series equipment offer efficient and flexible solutions for modern access networks.
Background and Challenges
With the expansion of access networks towards high - definition video, cloud computing, and Internet of Things applications, Fiber to X (FTTx) has emerged as an optimal choice owing to its substantial bandwidth potential. Meanwhile, passive optical network (PON) technology has become the mainstream in wired access networks. Nevertheless, network infrastructure confronts unprecedented challenges in terms of the integration of new and old services and upgrade costs.
Technology Generational Conflict
Different generations of PON technologies (e.g., GPON and XGS - PON) employ distinct uplink and downlink wavelengths. As a result, the OLT of the new technology and the ONU of the old technology accessing the ODN cannot be activated due to wavelength conflicts.
High Upgrade Costs
Upgrading traditional networks necessitates re - laying or large - scale modification of fiber optic links, entailing high material and labor costs as well as extended construction periods.
Rigid Service Deployment
Traditional ODN typically supports only one type of PON service and is unable to simultaneously satisfy the XGS - PON service requirements of high - end users and the GPON + CATV service requirements of ordinary households. Consequently, fine - grained service deployment cannot be achieved.
Investment Strategy Hesitancy
Operators' concerns regarding new technologies phasing out old equipment or existing assets lead to strategic hesitancy in investment.
Principles of Technology
Our FWDM series and CEx - WDM series products are developed to address the aforementioned core issues. By leveraging wavelength division multiplexing technology, these products can simultaneously transmit multiple optical signals of different wavelengths in a single fiber, effectively achieving the synthesis and separation of multi - service signals and significantly enhancing the resource utilization of the fiber.
We offer two product series: the FWDM series and the CEx - WDM series, available in either LXG card type or 1U whole - machine type.
Product Technical Features
FWDM Series
The FWDM series is based on thin - film filtering technology, which can precisely separate or combine light signals of different wavelengths. This structure enables a single fiber to concurrently carry both bidirectional data and unidirectional video services, remarkably improving the efficiency of fiber resource utilization.
The 1550nm wavelength of CATV is dedicated to downlink video broadcasting services.
The 1310/1490nm of PON and 1270/1577nm of XGS - PON are responsible for the uplink and downlink PON services. Multi - service integration does not interfere with each other.
It features low insertion loss (≤0.8dB), large channel isolation (≥30dB), high return loss (≥45dB), and a wide operating temperature range (- 40 °C to + 85 °C).
The port service type and the number of ports support personalized customization, facilitating precise investment.
As passive devices that do not require power supply, they reduce additional costs such as electricity bills and lower the system failure rate.
These excellent performance characteristics ensure that FWDM devices can provide stable and reliable services in a wide range of application environments, meeting the high standards of carrier - grade equipment.
CEx - WDM
CEx - WDM is a key product in the evolution of PON technology, primarily aiming to ensure a smooth upgrade of PON networks and the coexistence of new and old networks.
The 1290 - 1330nm/1480 - 1550nm wavelength range of GPON is responsible for uplink and downlink GPON services.
The 1260 - 1280nm/1575 - 1580nm wavelength range of XGS - PON is responsible for the uplink and downlink XGS - PON services.
The 1524 - 1544nm/1596 - 1625nm wavelength range of NG - PON2+PtP is responsible for uplink and downlink NG - PON2+PtP services. Multiple new and old PON services can coexist without interference and achieve a smooth upgrade.
The 1625 - 1675nm wavelength of OTDR is responsible for OTDR detection signals and is equipped with an OTDR fiber optic detection port for troubleshooting.
It has low insertion loss (GPON≤0.9dB, XGS - PON≤1.1dB, NG - PON2≤1.3dB, OTDR≤1.6dB), high channel isolation (≥30dB for all channels), and high return loss (≥55dB).
The port service type and the number of ports support personalized customization, enabling precise investment.
As passive devices that do not require power supply, they reduce additional costs such as electricity bills and lower the system failure rate.
This design allows network operators to significantly increase network capacity by simply upgrading equipment at both ends without replacing the base optical distribution network, substantially reducing the cost of network evolution.
Product Application Scenarios Integration of CATV and PON Networks
In the application of the convergence of the three networks, the FWDM series equipment achieves single - fiber three - way transmission by multiplexing the 1550nm video broadcast signal of CATV and the 1310nm/1490nm & XGS - PON 1270nm/1577nm data signals of the PON system into a single fiber, significantly conserving fiber resources.
Smooth Upgrade of PON Networks
For network operators requiring an evolution from GPON to XGS - PON and even NG - PON2, the CEx - WDM series provides an ideal transition solution. Existing GPON users and new XG(S) - PON users can coexist in the same ODN network, and operators can gradually upgrade user equipment based on market demand to maximize the protection of existing investments.
Application diagram of FWDM/CEx-WDM series products
Product Advantages
-Easy Deployment**: Featuring “plug-and-play” upgrades. At the office end, CEx - WDM or FWDM devices are deployed, and the new and old OLTs are respectively connected to the corresponding ports of these devices. At the user end, for users requiring upgrades, the corresponding ONUs are replaced with zero impact and zero interruption to existing users, thereby achieving a “hot upgrade”.
-Operation and Maintenance Convenience**: Simplifying the network architecture. Operators are not required to maintain multiple separate physical networks and fiber - optic resources for different generations of PON technology. All services are carried on the same physical fiber - optic network, which significantly simplifies the network topology and reduces the complexity and cost of operation and maintenance.
-Investment Convenience**: Enabling precise investment and quick return. The initial investment is reduced, and there is no need to lay fiber on a large scale for new business. The business launch time is accelerated, and the deployment time of new business is significantly shortened. Precise investment is achieved by upgrading equipment in areas with clear user demand and willingness to pay, thus increasing the return on investment.
Strategic Convenience**: Maintaining a competitive edge at all times. In the era of 50G PON, the same ODN and the same FWDM/CEx - WDM evolution concepts still hold. This allows operators to roll out leading service volumes at a lower cost and faster speed in the competition and always maintain a competitive edge.
Summary:
With the continuous expansion of 5G scale and the accelerated popularization of 10 - gigabit optical network access to the home, the demand for multi - service bandwidth in access networks is continuously increasing. Our FWDM series and CEx - WDM series equipment have realized multi - service converged transmission in current fiber access networks, addressed the technical challenges in network convergence and upgrading, and provided a smooth path for future network evolution. These high - performance wavelength - division multiplexing devices will play an increasingly important role in constructing a more efficient, more economical, and smarter optical network infrastructure.
