Indoor Flexible Armored Cable

Nov 16, 2025

Flexible armored optical cable is mainly installed indoor. It is designed with the spiral armor, braided mesh, etc., to enhance the tensile strength, pressure resistance, bending resistance and other capabilities of the optical cable, prevents damage by rodents, to improve the convenience of wiring and reduce the maintenance cost.

Mode Field Diameter:
It is used to characterize the distribution of the fundamental mode light in the core area of single mode fiber. In optical fiber, the optical power is not completely concentrated in the core for transmission, and part of them is transmitted in the cladding. The core diameter cannot reflect the power distribution in the optical fiber. Therefore, the concept of effective area is proposed. If the effective area is small, the density of the optical fiber cross section is large, and excessive density will cause nonlinear effects. Therefore, for transmission optical fiber, the larger the mode field diameter, the better.
Theoretically, there is only one mode (fundamental mode) transmission in single mode fiber, but the fundamental mode field in single mode fiber is not completely concentrated in the core, and a considerable part of the energy exists in the cladding. Therefore, the core diameter cannot be used to represent the light transmission range on the cross section like multi-mode optical fiber, and can only be represented by the mode field diameter.

Fiber cutoff wavelength:
The operating wavelength of a single-mode fiber transmission system must be greater than the cutoff wavelength, otherwise the fiber will operate in the dual-mode region.

Fiber bandwidth
There are few light transmission paths in a single-mode fiber, and the inter-modal dispersion is small, even negligible. The laser dispersion of the LD optical transmitter that matches it is small, and the transmission bandwidth of a single-mode fiber can be considered as infinite and meaningless. Therefore, this parameter is for multimode fibers. The smaller the fiber dispersion, the larger the bandwidth. The 50μm fiber core is selected because the number of transmission modes in this fiber is approximately 1/2.5 of the transmission modes in a 62.5μm multimode fiber. This can effectively reduce the modal dispersion of multimode fibers and increase the bandwidth

Overfilled modal bandwidth:
In the past, LEDs were used as light sources, and it is overfilled launch. All modes (hundreds) of the fiber were excited, and each mode carried a portion of the power. The distortion of the central refractive index of the fiber only affects the delay characteristics of a few modes, and has a relatively limited impact on the fiber modal bandwidth. The measured multimode fiber bandwidth is correct for systems using LED as the light source.
When using a laser as the light source, the laser spot is only a few microns, and the divergence angle is smaller than that of an LED, so it only excites a few modes transmitted in the center of the fiber. Each mode carries a considerable amount of power. The influence of the refractive index distortion of the fiber center on the delay characteristics of these only, a few modes cause a significant decrease in the bandwidth of the multimode fiber. Therefore, the traditional OFL cannot be used to measure the bandwidth of a multimode fiber using a laser as the light source.

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