Difference Between Single-mode And Multi-mode Fiber Cabling

In recent years, industrial networks have seen an explosion in growth and performance demands as newer technologies such as Industrial Internet of Things (IIoT) and Industry 4.0 devices come online. To keep pace with these technologies, more companies are implementing fiber optics to expand their networks and increase bandwidth.

Fiber optics has immense bandwidth capacity with potential speeds exceeding 100Gpbs. By default, it’s considered to be a more secure form of communication media due to its glass fiber strands that make it extremely difficult to “eavesdrop” or “tap” without noticeable degradation. It can also be installed at long distances with estimates ranging from 1m up to 120km depending on the cable type. Fiber optic cabling is also resistant to electromagnetic interference, making it ideal for industrial environments and spaces with fluctuating power.

Fiber optic cabling offers many advantages over traditional cabling and is the preferred media for data links in industrial environments. When implementing fiber optics in an industrial environment, specialized industrial media converters such as serial to fiber converters may be needed to transmit data.

Fiber Optic cabling comes in two basic modes, Single-Mode and Multi-mode. While both modes have different characteristics and serve different purposes, their structural makeup is still the same; an inner core made of purified silica glass, an outer glass known as cladding, and protection by buffer or jacket. In extreme environmental conditions, specialized types of reinforced fiber optic cabling are used, this may involve interlocking or corrugated armored jackets.

Multi-mode fiber uses a large diameter glass core which provides multiple modes or pathways for light to travel. The multiple modes allow more light (essentially data) through the cable. However, at longer distances, the light will start to experience dispersion (distortion in light) which can limit data transmissions through unclear, incomplete signaling on the receiver end.

Characteristics of Multi-Mode:
- Larger core diameter, usually 50 – 100 Micrometers, (62.5 most common)
- Widely used cable in LAN networks today
- Easier to terminate
- Transmitters and receivers are more economical
- Used at shorter distances

Single-Mode Fiber uses a narrow glass core with one mode or pathway for transmitting light. Unlike multi-mode, single-mode doesn’t have different light paths that reflect light off the cladding but instead has a single light beam. With no light reflection, there is less dispersion and therefore light signals can be transmitted over longer distances.

Characteristics of Single-Mode:
- Small core diameter, 8 to 12 microns
- Widely used cable in WAN networks today
- More difficult and costly to terminate
- Transmitters and receivers are more expensive
- Typically used over long distances

If you have any questions regarding the difference between Single-Mode and Multi-Mode for industrial application, please feel free to speak with one of our engineers who can help you decide which is best for your industrial application.