What is the difference between transmission distance and refractive index of single-mode fiber and multimode fiber?

Transmission distance of single-mode fiber: 64-channel transmission of 40G Ethernet can be as long as 2,840 miles on a single-mode cable. The single mode fiber is mainly composed of a core, a cladding layer and a coating layer.The core is made of a highly transparent material.The cladding has a refractive index slightly smaller than the core, resulting in an optical waveguide effect that allows most of the electromagnetic field to be trapped in the core.The coating acts to protect The fiber is protected from moisture and mechanical abrasion, while increasing the flexibility of the fiber. Outside the coating layer, a plastic jacket is often added.

What is the difference between single mode fiber and multimode fiber?

Difference in refractive index: Single-mode fibers use a step index profile. Multimode fibers can use step index profiles or graded index profiles.Therefore, quartz fibers can also generally use multimode step index fibers, multimode graded index fibers, and single mode step index fibers. Three kinds.

The difference in transmission mode: a single-mode fiber can only transmit one mode for a given operating wavelength, and multimode fiber can transmit several modes.The propagation of electromagnetic waves in the optical fiber belongs to the dielectric circular waveguide.When the light is totally reflected at the interface of the medium, the electromagnetic wave is confined in the medium, which is called guided wave or guided mode. For a given guided wave and operating wavelength, there are a variety of incident conditions that satisfy the conditions of total reflection, called different modes of guided waves. Divided into multimode fiber and single mode fiber in transmission mode.

The difference in transmission distance: the transmission distance and transmission bandwidth of single-mode fiber are obviously due to multimode fiber. If the transmission distance is greater than 5 km, the large-band data signal is transmitted for a long time to select a single-mode fiber.If the transmission distance is only a few kilometers, multi-mode is the best choice because the LED transmitter/receiver requires laser light than the single mode. It’s much cheaper.

The difference in wavelength of fiber transmission: single-mode fiber has a small core diameter and can only be transmitted in a single mode at a given operating wavelength, with a transmission bandwidth and a large transmission capacity. Multimode fiber is an optical fiber that can transmit simultaneously in multiple modes at a given operating wavelength. Multimode fiber has poorer transmission performance than single mode fiber.