High-Quality Optical Fiber End Cap Manufacturers & Factory

The ideal end cap length $L$ depends on the fiber's Numerical Aperture ($NA$), core diameter, and target output beam diameter. To safely reduce the power density, the beam must diverge within the coreless quartz block until its diameter reaches at least 50% to 70% of the end cap facet diameter without clipping the outer cylinder walls. For a standard 20/400 μm fiber ($NA \approx 0.065$), an end cap length between 3.0 mm and 10.0 mm is commonly utilized to ensure the surface power density drops below catastrophic damage thresholds.

JGS1 is synthesized via chemical vapor deposition of high-purity silicon tetrachloride (SiCl₄), leaving it virtually free of microscopic metallic impurities (Fe, Ti, Al < 0.1 ppm) and micro-bubbles (Bubble Class 0). This eliminates internal scattering centers that cause thermal lensing or bulk breakdown under kilowatt-class loads. Standard JGS2 is melted from natural quartz crystals and contains trace mineral contaminants that absorb high-intensity NIR laser radiation, making JGS1 the mandatory standard for high-power laser delivery.

A perpendicular 0° facet reflects approximately 3.5% of incident light directly back along the optical axis due to Fresnel reflection. In contrast, an 8° angled polish directs the reflected wavefront at an angle of roughly 16° relative to the fiber axis, thoroughly exceeding the critical acceptance angle of the fiber core. This retro-reflected power escapes into the cladding or external beam dumps, providing over 50 dB of return loss isolation.

Specialized large-diameter glass processing workstations equipped with ring-filament heating, CO₂ laser heating, or wide plasma arc discharge (such as Vytran GPX/LDS series, 3SAE Large Diameter Splicer, or Fujikura FSR series) are recommended. These systems provide homogeneous circumferential thermal soaking across the end cap diameter, ensuring a bubble-free, stress-annealed fusion interface without core distortion.

Every shipment includes a comprehensive Certificate of Conformance (CoC), material traceability certificates verifying synthetic silica grade and OH content, spectrophotometer transmittance/reflectance curves (PerkinElmer Lambda 1050+), optical surface roughness AFM/interferometer maps, and dimensional CMM inspection reports verifying length, diameter, and chamfer tolerances.