Create Config

MULTIMODE & SINGLE MODE FIBER OPTIC CABLES

How Light Travels Through the Fibers Determines the Features of Each Mode

 

How Does Fiber Optics Work?

As explained by the Fiber Optics Association, fiber optics is the communications medium that sends optical signals down hair-thin strands of extremely pure glass cores. The core is surrounded by the cladding that traps the light in the core.

Fiber Cable Construction diagram

Core & Cladding Sizing

Fiber types are identified by the diameters of the core and cladding, expressed in microns. Multimode fiber is available in two sizes, 62.5 or 50 microns, and four classifications: OM1 (62.5/125 µm), OM2, OM3, OM4 (50/125 µm). The diameter of a single mode core is 9µm. Both fiber types have a cladding diameter of 125 µm or microns.

Fiber mode multimode and single mode diagram

Multimode Fiber

Light travels through a large core in many rays called modes (multiple modes). Due to refraction, the rays are reflected from the cladding surface back into the core as they move through the fiber.

 

Single Mode Fiber

 

Single mode fiber has a much smaller core which forces the light to travel in one ray or mode (a single mode) with little light reflection so the signal will travel further.

Fiber mode travel multimode graded index and single mode diagram

Your application requirements determine which mode you use. Refer to the chart below for a comparison of the two modes.

Features Multimode Single Mode
Core/Cladding Size 50/125 μm or 62.5/125 μm 9/125 μm
Wavelengths 850 nm, 1300nm LED sources 1310nm, 1550nm Laser sources
Bandwidth Up to 4 GHZ Up to 100,000 GHZ
Distance (determined by cable, equipment & data protocol) Typically under 2km Typically over 2km
Benefits Less immune to contamination
Less expensive
Low cost sources
Lower loss
High signal quality
High bandwidth
Applications Data centers, 10G, 40G, and 100G Ethernet protocols, MADI digital audio, CCTV, security systems Long-haul networks, outside broadcast, ENG crews, sporting and live events