Multi -mode fiber type

Multimode fiber (MMF) is a type of optical fiber that allows multiple modes of light to propagate through it. MMF has a larger core diameter than single-mode fiber (SMF), typically ranging from 50 microns to 62.5 microns. In this article, we will discuss the classification and performance analysis of multimode fiber.

Classification of Multimode Fiber

Multimode fiber can be classified based on the following criteria:

Core diameter:

The core diameter of MMF ranges from 50 microns to 62.5 microns. MMF with a core diameter of 62.5 microns is commonly referred to as OM1 (Optical Multimode 1) fiber, while MMF with a core diameter of 50 microns is referred to as OM2 fiber.

Modal bandwidth:

The modal bandwidth of MMF refers to the maximum frequency of light that can be transmitted through the fiber without distortion. It is expressed in megahertz-kilometer (MHz-km) and is dependent on the core diameter and refractive index of the fiber. MMF with a modal bandwidth of 200 MHz-km is referred to as OM1 fiber, while MMF with a modal bandwidth of 500 MHz-km is referred to as OM2 fiber.

Wavelength:

MMF can also be classified based on the wavelength of light used for transmission. MMF is typically used with a wavelength of 850 nm or 1300 nm. MMF designed for 850 nm is referred to as OM1, OM2, OM3, or OM4, while MMF designed for 1300 nm is referred to as OM1 or OM2.

Performance Analysis of Multimode Fiber

The performance of MMF can be analyzed based on the following parameters:

Attenuation:

Attenuation is the loss of signal strength as light travels through the fiber. MMF has higher attenuation than SMF due to the presence of multiple modes of light, which can cause modal dispersion and intermodal dispersion. However, the attenuation of MMF can be reduced by using high-quality fiber and connectors, and by maintaining the fiber properly.

Bandwidth:

Bandwidth refers to the amount of information that can be transmitted through the fiber. MMF has lower bandwidth than SMF due to the presence of multiple modes of light, which can cause modal dispersion and limit the maximum data rate that can be transmitted through the fiber. However, the bandwidth of MMF can be increased by using higher-quality fiber, using graded-index fiber, or using wavelength division multiplexing (WDM) techniques.

Dispersion:

Dispersion refers to the spreading of light as it travels through the fiber. MMF has higher dispersion than SMF due to the presence of multiple modes of light, which can cause modal dispersion and intermodal dispersion. However, the dispersion of MMF can be reduced by using graded-index fiber, using higher-quality fiber and connectors, or by using dispersion compensating modules (DCMs).

Modal noise:

Modal noise is a type of noise that occurs in MMF due to the interference between different modes of light. It can be caused by mechanical stress on the fiber, bending of the fiber, or variations in the refractive index of the fiber. Modal noise can be reduced by using higher-quality fiber and connectors, by reducing mechanical stress on the fiber, or by using mode conditioning cables.

Connector loss:

Connector loss refers to the loss of signal strength that occurs when light passes through connectors between fiber segments. Connector loss is higher in MMF than in SMF due to the larger core diameter of the fiber. Connector loss can be reduced by using high-quality connectors, cleaning and inspecting the connectors regularly