Single Mode vs Multi Mode Fiber Transceivers

The key difference between SMF and MMF?
...Distance and cost!

• Single Mode Fiber has a greater distance potential and can support runs between 2 meters and 10,000 meters.
• Multimode generally has a reach up to ~550 meters, whereas single mode has the potential to reach 10,000 meters (40,000 meters with ER)
• Single mode fiber -> lower power loss characteristic than multimode fiber, which means light can travel longer distances through it than it can through multimode fiber.

Costs

• The optics for SMF are twice the cost of MMF optics.
• BUT when installed as part of a project, the extra cost of SMF is negligible compared to MMF.
• The fragility and increased cost to produce single mode fiber makes it more expensive to use, which is why multimode is typically used when you don’t need the distance of single mode.

Speed
Both single-mode and modern multi-mode fiber can handle 10G speeds.

The distance requirement is critical

• Multi-mode which can get you 300-400 meters.
• Single-mode can get you 10km, 40km, 80km, and even farther – you just need to use the appropriate optic for the distance required. Prices go up accordingly.

Compatibility issues:

• They are not compatible.
• You cannot mix multimode and single mode fiber between two endpoints.
• The optics are not compatible either.

How they work:

• Multi-mode fiber (MMF) – uses a much bigger core and usually uses a longer wavelength of light. Because of this, the optics used in MMF have a higher capability to gather light from the laser. In practical terms, this means the optics are cheaper.
• Single-mode fiber (SMF) has much tighter tolerances for optics used. The core is smaller and the laser wavelength is narrower. This means that SMF has the capability for higher bandwidth and much longer distances in transmission. Single-mode fiber has a smaller core (9 micron), resulting in less light diffraction over distance than multimode fiber (50, 62.5 micron).

Are single mode transceivers a better option for the future?

• Using only single mode lets you use one fiber type for everything (fewer optics, cable types to spare)
• No likelihood of obsolescence (eg, OM3 seemed like it was current for ~3 years)
• Offers single-pair options for 40 & 100g
• Offers single-fiber options at 1 & 10g
• Although the optics are more expensive they’re < 2x while offering much longer reach (remember to buy OEM optics, not rebadged)
• With SMF it also means you won’t need to rip out your MMF fiber plant to upgrade speeds in a few years.

Courtesy of: Blue Wave Micro