IEC 61300-3-53:2020

Overview

IEC 61300-3-53:2020 specifies a standardized method for measuring Encircled Angular Flux (EAF) of step-index multimode waveguides (including optical fibres) using two‑dimensional far‑field data. The standard applies to multimode waveguides where most transverse modes are excited and covers channel waveguides and fibres (but not slab waveguides). This second edition (2020) replaces the 2015 edition, adds graded‑index multimode waveguides to the scope, reorganizes measurement method content, and includes new Annexes C and D; the June 2023 corrigendum is incorporated.

Key topics and technical requirements

• Measurement principle: Calculation of EAF from two‑dimensional far‑field intensity distributions to quantify angular power distribution of multimode sources.
• Applicable fibre types: Waveguides/fibres defined as A1 (IEC 60793‑2‑10), A3 (IEC 60793‑2‑30) and A4 (IEC 60793‑2‑40).
• Measurement methods:
  • Method 1 - fθ lens imaging: Uses an fθ lens and camera to map angular flux to an image sensor.
  • Method 2 - Direct imaging: Uses integrating spheres, single‑mode fibre scanning or imaging devices to capture far‑field power distribution.
• Equipment and calibration: Requirements for micro‑positioners, far‑field optical systems, cameras/detectors, power meters, calibration light sources and geometric calibration procedures.
• Data processing: Background noise removal, optical/mechanical centre determination, coordinate conversion (x‑y to polar), and computation of encircled angular flux curves.
• Uncertainty and artifacts: Consideration of CCD shading effects (Annex C), system recommendations (Annexes A and B) and a template compliance test using defined launch optics (Annex D).
• Results and reporting: Standard EAF charts and a list of information provided with each measurement and additional data available on request.

Applications and users

IEC 61300-3-53 is practical for:

• Fibre and waveguide manufacturers - validating modal output and launch conditions.
• Component and connector test labs - specifying and verifying angular power distributions for passive components.
• Optical system designers and OEMs - ensuring compatibility of multimode sources with receivers and modal launch specifications.
• Telecom and datacom test engineers - assessing link behavior sensitive to modal distribution and modal bandwidth effects.
• Standards bodies and conformity assessment organizations - harmonized test method for performance claims and compliance testing.

Practical use cases include characterizing light source launch conditions, troubleshooting modal‑dependent loss, and verifying component performance under defined angular flux conditions.

Related standards

• IEC 61300 series - general fibre optic interconnecting devices and basic test procedures.
• IEC 60793‑2‑10, IEC 60793‑2‑30, IEC 60793‑2‑40 - referenced fibre type specifications (A1, A3, A4).

Keywords: IEC 61300-3-53, Encircled Angular Flux (EAF), EAF measurement, multimode waveguide, far field data, fibre optics testing, fθ lens, direct imaging, step index multimode.