Fiber Optic Components and Peripheral Products
Fiber Optic Bare Fiber

Fiber Optic Bare Fiber

SUMITA’s bare optical fiber is made of multi-component/borosilicate glass fiber drawn from our original glass materials.

Specifications & Property

Numerical aperture (NA) and opening angle of fiber optics are calculated by refractive indices of core and clad material. The equation is as follows:

We, SUMITA, offer 7 kinds of fiber optics by the difference in opening angles.

Fiber Types and Specifications

Wavelength Material Type of fiber optics Numerical Aperture (NA) Opening angle (2θ) Property
Visible Borosilicate glass SOG-120C* 0.87 120° Capable of illuminating a large range in short working distance. Ideal for a wide-range illumination (e.g. light guides).
SOG-100 0.77 100° Having a wider NA than the standard product (SOG-70S), SOG-100 can illuminate a relatively larger range. Suitable for a wide-range illumination.
SOG-70S 0.57 70° Having a standard NA and an excellent transmittance, SOG-70S can transmit light to relatively long distance.
SOG-35C* 0.29 35° Having relatively lower NA than the standard product (SOG-70S), SOG-35 can project light into a tighter area. Optimal for illumination for small and narrow areas, as well as for optical sensors.
SOG-15 0.13 15° N.A is smaller than that of quartz fiber. The main distinguishing feature of SOG-15 is its narrow NA compared to that of quartz fibers. Ideal for lighting a specified area precisely (e.g. optical sensors).
Plastic SOP-20 0.50 60° Core diameter: 486 um, clad diameter: 500 um (20 mil)
Economical, excellent bending resistance, and low temperature resistance.
NIR (Near IR) Borosilicate glass SOG-70SIR 0.57 70° Excellent transmission at 1100- 1350 nm compared to SOG-70SIR.
UV Borosilicate glass ST365-35 0.29 35° Usable borosilicate glass fiber for UV light (365nm)
Complex light guides available with thinner diameter than silica fiber
Fused silica glass SOQ-200 0.22 25° Core diameter: 200 um, clad diameter: 208 um, jacket diameter: 240 um
Fused silica glass fiber with excellent transmittance in ultraviolet region.

* SOG-35C/SOG-120C has improved transmittance in short wavelength compared to the previous model SOG-35/SOG-120S.

What is Fiber Optics?

Structure and Principle

An optical fiber used in light guides consists of a core surrounded by a clad layer (see Figure 1).
- Core is made of optical glass which has an excellent transmission property.
- Clad is made of weather-resistant glass, and works as a covering material.
This structure of fiber allows light to travel along the fiber through repeated total internal reflections* inside the core from one end to the other.

Total internal reflections is the phenomenon that reflection of the total amount of incident light at the boundary between two media (see Figure 2). The phenomenon occurs at the boundary between two mediums having different refractive indices, such that if the incident angle in the first medium is greater than the critical angle, then all the light is reflected back to that medium.

Figure 1. Structure of fiber optics

Figure 2. Principle of Total Internal Reflection n1>n2 (n: refractive index)

Borosilicate glass

  • Transmittance by Length

    SOG-70S
    Measurement conditions
    Measurements are based on light guides which have bundle diameter of 5 mm, individual fiber diameter of 50μm. Core ratio of the fiber is 70% approximately.
  • Comparison of Transmittance by Glass Types

    Length of 2 meters
    Measurement conditions
    Measurements are based on light guides which have bundle diameter of 5 mm, individual fiber diameter of 50μm. Core ratio of the fiber is 70% approximately.
  • Transmittance by Length of SOG-70SIR
    (NIR Optical Fiber)

    SOG-70SIR
    Measurement conditions
    Using light guides which have bundle diameter of 5 mm, individual fiber diameter of 50μm. Core ratio of the fiber is 70% approximately.
  • Transmission Curves

    ST365-35
    Measurement conditions
    Bundled Diameter 4mm x length 1000mm

    *ST365-35/SOG-70S: Individual diameter 50μm Silica fiber: Jacket diameter 240 μm

Fused silica glass/ Plastic fiber

  • Comparison of Transmittance by Material

    Length of 1 meter
    Measurement conditions
    Light gude bundles which diameter of 2 mm, and total length of 1000 mm are used
  • Transmission Loss (Fused silica glass fiber)

    SOQ-200
    Measurement conditions
    SOQ-200(fused silica glass fiber) is used
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