What is a "large-diameter core" patch cord?

OFSCN Global Technical Center OFSCN Technical Knowledge Base
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These jumpers are not usually used for transmitting signals; what are they used for?

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In optical engineering, the purpose of a Large-core Fiber Patch Cord (or large-core energy patch cord) is entirely different from that of traditional communication fiber patch cords.

Ordinary communication fibers (such as single-mode fiber, with a core diameter of only about 9\ \mu\text{m} ; or standard multimode fiber, typically with a core diameter of 50\ \mu\text{m} or 62.5\ \mu\text{m} ) are primarily used to carry low-power optical signals, with the core focus being on low attenuation, low dispersion, and signal integrity.

On the other hand, large-core fiber patch cords (with core diameters typically ranging from 105\ \mu\text{m} to 1000\ \mu\text{m} , or even larger) are not designed for transmitting high-frequency modulated signals carrying data information. Instead, they are used to conduct the following physical energy and optical components:

1. Optical Energy (Laser Power Delivery)

This is the most crucial application scenario for large-core patch cords. When transmitting high-power lasers ranging from hundreds of milliwatts (mW) to thousands of kilowatts (kW) is required, using ordinary single-mode fiber would result in extremely high optical power density due to the very small core area. This can lead to the thermal lensing effect or even catastrophic optical damage (COD, i.e., fiber melt or end-face burning) at the fiber end face.

  • Physical Mechanism: By multiplying the cross-sectional area of the fiber core, large-core fibers can effectively reduce the optical power density per unit area, thereby achieving safe and efficient transmission of high-power laser energy.
  • Application Examples: Industrial laser welding, cutting, and marking, as well as surgical lasers in the medical field (e.g., Holmium laser, Thulium laser for lithotripsy and tissue ablation).

2. Pump Light Delivery

In the structure of high-power fiber lasers or optical amplifiers (such as Erbium-doped fiber amplifiers), high-power pump energy generated by multiple semiconductor pump sources (Pump LDs) needs to be injected into the gain medium. This incoherent, high-energy pump light is converged and transmitted through large-core multimode fibers.

3. Weak Optical Signal Collection

Large-core fibers possess a very large light-gathering area and a high numerical aperture ( \text{NA} ), meaning they have extremely strong light-collecting capabilities (Etendue).

  • Physical Mechanism: Modal dispersion in large-core multimode fibers is very severe, making it impossible to maintain the waveform integrity of high-speed signals. However, for the sole purpose of “collecting light energy,” a large core is an excellent choice.
  • Application Examples:
    • Spectroscopic Analysis: Used to collect signals from Raman Scattering, weak Fluorescence, or absorption spectra, and guide them into a spectrometer.
    • Astronomical Observation: Collecting the faint incoherent light from distant celestial bodies.

4. High-Brightness Illumination

Used to transmit high-intensity white light, ultraviolet light, or other light sources to hard-to-reach areas, such as deep illumination in medical endoscopes, illumination for microscopic imaging, or high-precision machine vision positioning light sources.

OFSCN® Product Association and Technical Support

Although high-power large-core laser energy transmission systems themselves (such as industrial-grade kW energy transmission fiber optic assemblies) are not part of OFSCN®'s standardized mass production sequence (OFSCN®'s core products mainly focus on high-precision fiber optic sensing, Fiber Bragg Grating sensor components, and optical communication in ultra-high temperature and harsh environments), OFSCN® provides support for high-temperature resistant connectors with SMA905 interfaces that can be used in multimode systems, light collection systems, and large-core coupling:

For experiments or industrial applications involving multimode energy transmission and weak spectral collection in special temperature zones, OFSCN® also supports customized armored encapsulation of various multimode fibers with seamless stainless steel pipes to meet the physical protection needs in harsh environments.