Step Index low-OH Visible-Near Infrared Spectrum Analysis(BGIR)

Step-index multimode low-water-peak visible-near-infrared silica fiber (BGIR Series)

400–2500nm ultrawide spectral coverage | Low-water-peak process | Step-index multimode | Visible to short-wave infrared light.

The BGIR series of optical fibers employs a step-index multimode structure and advanced low-water-peak manufacturing processes to minimize hydroxyl (OH⁻) concentration, achieving low-attenuation transmission over an extremely wide spectral range of 400nm–2500nm. Compared to ordinary silica fibers, which exhibit a significant water absorption peak near 1380nm, BGIR effectively 'flattens' this loss valley, opening up a full-band transmission path from visible light to short-wave infrared (SWIR). The products are available with a numerical aperture of NA 0.22 and core diameters of 100/200/300/400/600µm, suitable for diverse applications such as spectral analysis, fiber optic sensing, laser medicine, thermal imaging, and high-power laser transmission.

Product Advantages

1. 400–2500nm Ultra-Wide Spectral Coverage

BGIR fiber covers a transmission spectrum from 400nm to 2500nm, spanning the visible, near-infrared, and short-wave infrared bands, making it an ideal carrier for spectral analysis, multi-wavelength laser transmission, and broadband light source coupling.

2. Low Water Peak & Flat Loss Across the Entire Band

Advanced dehydration technology minimizes OH⁻ concentration, eliminating the water absorption peak (“water peak”) near 1380nm, achieving a flat attenuation curve from visible to short-wave infrared, ensuring consistent signal transmission across all wavelengths.

3. Step-Index Multimode Design

Precisely controlled step refractive index profile supports multimode transmission and high coupling efficiency. Core diameter selectable from 100–600µm, numerical aperture NA 0.22, compatible with various light sources such as LEDs, SLDs, and laser diodes.

4. Excellent Temperature and Mechanical Properties: Offers two coating options: acrylate (-40℃~+85℃) and polyimide (-65℃~+300℃), adaptable to different environmental requirements. The polyimide coated version is particularly suitable for high-temperature industrial and medical sterilization applications.

Applications

Spectral Analysis: Visible-Near Infrared Spectrometer (400–2500nm full-spectrum fiber optic probe)

Fiber Optic Sensing: Temperature, Strain, Gas Sensing (covering multiple characteristic absorption wavelengths)

Laser Medicine: 980nm, 1470nm, 1550nm, 1940nm Medical Laser Transmission

Infrared Thermal Imaging: Light Source/Signal Transmission for Short-Wave Infrared (SWIR) Imaging Systems

Industrial Laser Processing: 1064nm, 1340nm High-Power Laser Transmission (Large Core Diameter Version)

Broadband Light Source Coupling: Supercontinuum Light Source, Flexible Light Guide for SLDs

Telemetry and Remote Sensing: Near-Infrared Spectroscopic Detection in the Field, Mineral Analysis

Scientific Research Experiments: Multi-wavelength Optical Path Construction, Tunable Laser Systems

Geometry & optical characteristics:

• Multiple core diameters can be chosen 100 / 200 / 300 / 400 / 600 um
  
• The ratio of cladding to core is about 1: 1.1.
  
• Numerical aperture of NA 0.22
  

High-OH fiber attenuation curve:

BGIR Optical Fiber selection reference Ta:

How to Achieve Broadband Transmission of 400–2500nm with Low Water Peak?

Traditional silica optical fibers exhibit a significant water absorption peak near 1380nm (caused by residual OH⁻ ions), with losses reaching tens of dB/km, severely limiting the usability of this band and adjacent wavelengths. Furthermore, OH⁻ also generates harmonic absorption bands in the visible light region (e.g., 720nm, 950nm), affecting transmission quality in the 400–1000nm range.

The BGIR series employs an improved chemical vapor deposition (MCVD) combined with a fluorine dehydration process to control the residual OH⁻ concentration in the fiber core to an extremely low level, thereby:

Smoothing the 1380nm water absorption peak;

Reducing harmonic absorption interference in the visible light region;

Extending the effective operating window to an ultra-wide range of 400–2500nm.

This enables BGIR to simultaneously meet multi-wavelength composite application scenarios such as visible light indication (e.g., 635nm red light), near-infrared laser transmission (e.g., 980nm, 1064nm), and short-wave infrared sensing (e.g., 1550nm, 2000nm) on a single optical fiber, greatly simplifying the system optical path design.