What is fiber optic cable and what are its types?

What is fiber optic?

Fiber optics is a technology that sends and receives data (information) in the form of light pulses over long distances using trends of fiber made of either glass or plastic.

What is fiber optic cable?

Fiber optic cables are network cables with fiberglass strands inside an insulated enclosure. Designed for high-performance long-distance data networks and communications.

The individual fiber optic elements are usually covered with a layer of plastic and placed in a protective tube suitable for the environment in which the cable is to be used. Different types of cables are used for a variety of purposes, such as long-distance communication or providing high-speed data transmission between different parts of a building.

It has high bandwidth and can transmit longer distances are the main advantages of fiber optic cable compared to wired cables.

Fiber material

Optical fibers are made of two types of materials: glass and plastic. They have a wide range of characteristics and are used in a variety of applications.

Plastic fibers are usually used to communicate very short distances and for domestic purposes.

Glass fiber is commonly used for short/medium range (multimode) and long-range (single mode) communications.

Patch cords

Patch cords, buffers, or jackets are frequently color-coded to indicate the type of fiber used. The type of connection is indicated by the color-coded strain relief “boot” that protects the fiber from bending at a connector. Color-coded shells are commonly used on connectors with a plastic shell (such as SC connectors). The following is an example of standard color coding for jackets (or buffers) and boots (or connector shells):

Cord jacket (or buffer) color

Types of Fiber Optic Cable

Single-Mode(Mono-Mode): Transmit infrared laser light and have small cores (about 9 microns in diameter).

Multi-Mode: It transmits IR(infrared) light from LEDs and it has larger cores (62.5 microns in diameter) than single-mode fiber.

Comparison of Single-mode and Multimode fiber optic cable.

Parameters Single-Mode Multi-Mode
Number of propagating mode Only One More than one
Core diameter Small Large
Optical Source LASER LED
Bandwidth More Less
Handling and Coupling Difficulty Easy
Initial cost of fiber Low High
Attenuation Less More
Transmission rate High Low
Signal transmission distance Long Short
General colour coding Yellow Aqua or Orange
Modal dispersion Absent Present
Numerical Aperture (NA) Low High
Used In Telecom and CATV In LANs and security systems

What are OS and OM type fiber optic cables?

We already described fiber optics are classified into two- Single-mode fiber cables and Multimode fiber.

Single-mode fiber cable is prefixed with ‘OS’ and Multimode fiber cable is prefixed with ‘OM’.

According to ISO/IEC 11801 and EIA/TIA standards, Single-mode are again classified into twoOS1 & OS2, Multimode are classified into four types- OM1, OM2, OM3 & OM4

Different types of OS fiber optic cables

The main difference between the OS1 and OS2fiber cables is based on the construction of the cable than the specification of optical fiber. OS1 cable has a tight-buffered construction, whereas OS2 cable has a loose tube or blown cable construction, which puts less strain on the fiber optics.The OS1 model is designed for indoor use up to 2000 meters with data rates from 1 to 10 Gigabit Ethernet.

OS2 fiber optic cables are designed for long-distance transmission from 5,000 to 10,000 meters at transmission rates of 1 to 10 Gigabit Ethernet.

Different types of OM fiber optic cables

In the early days, OM1 (62.5/125m) and OM2 (50/125m) multi-mode fiber optics were used on-premises applications. These cables are designed to be used to work with LED transmitters and they support ethernet ranging from 10 Mbits/s to 1 Gbit/s.Later, when users needed a faster network, 50/125 m laser-optimized OM3 and OM4 cables were deployed with bandwidths supporting data transmission over 10 Gigabit Ethernet.

The OM3 and OM4 are laser-optimized multimode cables (LOMMFs) designed for use with 850nm VCSELs with modulation speeds above 10Gbps, with LED maximum modulation speeds of 622Mbps.

The modal bandwidth of OM cables is frequently used to characterize themOM cables are often characterized by modal bandwidth. Since the light sources OM1 and OM2 typically exceed the numerical aperture of the fiber, the modal bandwidth value is commonly known as the “overflow trigger”. In addition to “focused triggering”, OM3 and OM4 require limited trigger conditions provided by the laser/VCSEL to achieve high modal bandwidth.

Fiber Optic Communication Terms


A cause of attenuation is where a light signal is absorbed into the glass during transmission.


The amount of light lost between the input and output of an optical fiber is measured as attenuation. The sum of all losses is referred to as total attenuation. Fiber optical losses are typically expressed in decibels per kilometer (dB/km).


It’s a device used for reducing the power of an optical signal.

Back Reflection:

The amount of light reflected from the polished end of a fiber connector.

Expressed in negative decibels (dB) in relation to incident power.


The bandwidth of an optical fiber is the frequency of the light beam used.


Protective coating over the fiber.

Insertion Loss:

Attenuation is caused by the insertion of a device (such as a connection point) into a cable.

Loss Budget:

The maximum amount of power can be lost over an optical link.


The core diameter of this fiber optic cable is much larger than the wavelength of light being transmitted. 50/125m and 62.5/125m are two common multimode fiber optic cable types.

Return Loss:

Return loss is a relative measure of the strength of the signal reflected from a transmission line or fiber-optic break. This measurement can be expressed in positive decibels (dB). Larger numbers have priority. Return loss = 10 log (incident power / return power).


A cause of attenuation optic signal. Scattering occurs when light collides with individual atoms of the cable glass.


A fiber optic cable with a small core that only allows one light mode to propagate.


A means of measuring light color. Expressed in nanometers (nm)

Advantages of fiber optic cable

  • Fiber optic networks can operate at very high speed.
  • Large carrying capacity (Bandwidth)
  • High resistance to electromagnetic noise from radios, motors, or other nearby cables.
  • Maintenance cost is less.

Disadvantages of fiber optic cable

  • Difficult to Splice
  • Expensive to Install
  • Highly Susceptible
  • Highly vulnerable while installing
  • More delicate than copper wires.