Moldova ONU Spectrum Splitter Parameters

ONU spectrum splitters in PON systems divide optical signals from an OLT to multiple ONUs using defined split ratios, wavelength filtering, and transmittance characteristics to optimize network performance and identification.

Split Ratios and Bandwidth Sharing

Optical splitters in PONs distribute a single optical signal from the OLT to multiple ONUs. Common split ratios include 1x2, 1x4, 1x8, 1x16, 1x32, and 1x64, with some networks using odd ratios like 1x3 or 1x5 to meet specific deployment needs . The split ratio determines how the bandwidth is shared among ONUs, but as long as the received power is sufficient, each ONU can operate effectively without degradation . Higher split ratios reduce the number of fibers required but increase insertion loss.

Wavelength Filtering and Transmittance

Advanced ONU spectrum splitters may include optical filtering structures in each light-out section. These filters allow identification of specific ONUs by wavelength or transmittance differences, enabling the OLT to detect which ONU is connected without scanning a wide wavelength range . Each light-out section can filter one or more wavelengths, and differences in transmittance or filtered wavelengths help distinguish multiple ONUs in the network.

Splitter Types

Two main types of splitters are used in FTTH networks:

• FBT (Fused Biconical Taper) splitters: Low-cost, suitable for small splits like 1:2 or 1:4.
• PLC (Planar Lightwave Circuit) splitters: Highly uniform, preferred for larger splits like 1:32 or 1:64 . PLC splitters provide better uniformity and lower insertion loss, making them ideal for high-capacity PONs such as XGS-PON or NG-PON2.

Deployment Architectures

Splitters can be deployed in two main architectures:

• Centralized splitting: Splitters are co-located at a central office or cabinet, allowing flexible assignment of ONUs via jumpers.
• Distributed splitting: Splitters are placed in closures or pedestals in the field, with fixed ONU assignments . Centralized splitting simplifies network management and reconfiguration, while distributed splitting reduces fiber usage in the feeder network.

Standards and PON Types

ONU spectrum splitters are used in various PON standards, including GPON, XGS-PON, and NG-PON2, supporting speeds from 2.5 Gbit/s to 40 Gbit/s. TWDM-PON systems may use multiple wavelengths to increase capacity, and splitters with wavelength-specific filtering help manage these channels efficiently .

Practical Considerations

When designing a PON in Moldova or similar regions:

• Choose split ratios based on subscriber density and fiber availability.
• Use PLC splitters for large splits to maintain uniform signal distribution.
• Consider wavelength filtering in splitters for easier ONU identification and network testing.
• Decide between centralized or distributed splitting based on operational flexibility and deployment cost. By carefully selecting splitter parameters, network operators can optimize bandwidth allocation, signal quality, and maintenance efficiency in FTTH deployments.