The differences of the cable

As the core of modern communication technology, optical fiber communication is widely used in various network environments. Fiber optic cables are mainly divided into single-mode fiber and multi-mode fiber, which have significant differences in structure, performance and application. This article will explore the differences between single-mode fiber and multimode fiber cables in detail in order to better understand their applicability in different scenarios.

Basic principles of optical fiber cables

Optical fiber communication uses optical signals to transmit data in optical fibers. An optical fiber consists of a core and cladding in which the light signal propagates forward by total internal reflection. The main difference between single-mode fiber and multimode fiber is the propagation mode of light in the core.

Core diameter and structure

Single-mode fibers have a small core diameter, usually 9 microns, while multimode fibers have a larger core diameter, usually 50 microns or 62.5 microns. This difference in diameter causes light to travel differently through the fiber. Due to the small core diameter, single-mode fiber can only allow one mode of light propagation, thus reducing light reflection and dispersion. The larger core diameter of multimode fiber allows multiple modes of light to propagate at the same time, which can provide higher bandwidth over short distances, but will cause dispersion and signal attenuation.

Wavelength and light source

Single-mode fibers typically use lasers as light sources and operate at wavelengths of 1310 nanometers and 1550 nanometers. These wavelengths of light have less attenuation when propagating in single-mode fibers and are suitable for long-distance transmission. Multimode fiber is commonly used light emitting diode (LED) or vertical cavity surface emitting laser (VCSEL), operating wavelengths of 850 nm and 1300 nm. These light sources cost less, but the divergence of light is large, suitable for short-distance transmission.

Bandwidth and data transmission capability

The bandwidth of a single-mode fiber is theoretically infinite because it allows only one light mode to pass through at a time, thus avoiding the mode dispersion in a multimode fiber. This allows single-mode fiber to support higher data transmission rates and longer transmission distances. The bandwidth of multimode fiber is limited by its optical mode, and the current maximum bandwidth of OM5 fiber is 28,000 MHZ ·km. In practical applications, single-mode fibers can support data transmission rates of up to 100Gbps and above, while multi-mode fibers can support rates of about 10Gbps over short distances.

Transmission distance

Because of its low attenuation and low dispersion characteristics, single-mode fiber is suitable for long-distance transmission, and the transmission distance can reach tens of kilometers or even hundreds of kilometers. For example, OS2 single-mode fiber can support longer distance 40G and 100G links. Multimode fiber is limited by dispersion and attenuation, and the transmission distance is short, generally between a few hundred meters and a few kilometers. For example, OM1 multimode fiber has a transmission distance of 200 meters in fast Ethernet.

The cost

Single-mode fiber is more expensive to manufacture because it requires higher precision and a more complex manufacturing process. In addition, photoelectric components such as lasers required for single-mode fibers are also more expensive than LED light sources for multi-mode fibers. Multimode fiber is low cost due to its large core diameter and relatively simple manufacturing process. This makes multimode fiber more advantageous in short-range applications where budgets are limited.

Application scenario

Single-mode fiber is widely used in long-distance communication, such as metropolitan area network, wide area network, fiber interconnection, etc. It is also commonly used in scenarios that require high bandwidth and long-distance transmission, such as telecommunications networks, connections between data centers. Multimode fiber is mainly used for short-distance communication, such as internal office networks and data center internal connections. It is also suitable for some cost-sensitive applications such as local area networks and video surveillance systems.

Sheath color and recognition

According to Telecommunications Industry Association (TIA) standards, single-mode fiber is usually coated with a yellow jacket, while multi-mode fiber is coated with an orange or aqua jacket. This color coding helps to quickly identify fiber types during installation and maintenance.

Sum up

Single-mode fiber and multi-mode fiber have advantages and disadvantages and are suitable for different application scenarios. With its high bandwidth, low attenuation and long-distance transmission capability, single-mode fiber becomes the ideal choice for long-distance communication and high-bandwidth demand scenarios. Multimode fiber is suitable for local area network and short distance communication because of its low cost and high bandwidth capability in short distance. When selecting an optical fiber type, you need to make a reasonable selection based on the specific communication requirements, budget, and application scenarios.

Future development trend

With the continuous development of communication technology, fiber optic cables are also constantly evolving. For example, the new OM5 multimode fiber enhances its potential for applications in scenarios such as the data center by supporting multiple wavelengths. At the same time, the technology of single-mode fiber is also constantly improving to meet the increasing demand for long distance and high bandwidth. In the future, fiber optic cables will continue to play an important role in the field of communication and continue to adapt to new technical challenges and market demands.

Through a detailed comparison of single-mode fiber and multi-mode fiber cables, we can better understand their characteristics and choose the appropriate fiber type according to specific needs.