How optical passives optimize fiber deep networks

As operators drive fiber deeper into their networks for increased speed and capacity, tolerances become tighter and margin for error becomes lower. That means quality is critical and every component in the network needs to perform better.

 

This blog post explores the purpose and function of PPC’s new product category of fiber optical passives and splitters to help service providers gain speed and bandwidth, and the crucial role these devices play in enhancing the transmission of high-quality, ultra-high-speed broadband to multiple subscribers.

 

Multiplexers

Optical signals are transmitted in wavelengths (or channels) from the headend to the transition point, or directly to the subscriber.

 

These wavelengths are combined using multiplexers (muxes) onto one fiber in order to travel the distance. They are then separated in a demultiplexer (demux) near the destination.

 

WDM – Wavelength Division Multiplexing 

WDM combines and transmits different wavelengths on a single fiber. Several variations of WDM can be used, depending on the number of channels that need to be multiplexed.

 

WDM offers the advantage of being easy and cost-effective to implement while enabling higher speeds and greater bandwidth capacity without the need to lay additional fibers.

 

CWDM – Coarse Wave Division Multiplexing 

CWDM puts up to 18 channels on a single fiber, while still enabling a generous 20 nanometer (20nm) spacing between channels. CWDM uses lower-cost transceivers and is a more economical solution to sophisticated dense wave division multiplexing (DWDM) designs.

 

CWDM is best suited to low density, short-run environments (typically less than 25 miles or 40 km depending on signal throughput). It is also ideal for networks that don’t offer potential for future expansion.

 

DWDM – Dense Wave Division Multiplexing 

DWDM is the preferred solution when capacity and reach are critical. It accommodates a greater number of channels in a smaller band to maximize the capacity of fibers – typically fitting 48 channels at 100GHz spacing (or 96 channels at 50GHz spacing) into the 3rd transmission window (or C-band) at 1550nm. 

 

DWDM C-Band channels can be amplified for longer-distance transmissions, generally greater than 40km or 25 miles. However, the tight tolerances of DWDM use sophisticated transceivers and highly-sensitive filters and prisms in the passive devices, so deployments typically cost more than CWDM.

 

BWDM – Band Wavelength Division Multiplexing

BWDM modules provide a method of combining groups of optical wavelengths onto a single fiber. A BWDM separates groupings of channels rather than single channels and is especially well suited to MDU applications or business parks where there are often more dense groupings of subscribers. 

 

OADM – Optical Add Drop Multiplexing

OADMs act as “on-and-off” ramps or by removing and rerouting individual wavelengths to specific destinations as the remaining signals continue down the trunk.

 

OADMs are ideal when dedicated wavelengths are needed to service businesses or clusters of subscribers.

 

Optical Splitters

Optical splitting enables operators to spread the cost of expensive optical components across a large number of subscribers by dividing the signal symmetrically into 2, 4, 8, 16, 32, 64 or 128 divisions.

 

These divisions can also be cascaded to spread the number of splits into smaller, optimized serving areas in accordance with the optical link budget.

 

Optical splitters are most commonly used in FTTx and passive optical networks (PONs) deployed in the headend/central office and the outside plant to extend optical signals to the customer premises. Optical splitters can take on different form factors depending on deployment needs.

 

Passives and other small components are critical to the network working efficiently and cost effectively. With experts like PPC, you can optimize your optical networks to get peak performance out of your fiber deep architecture.