ISO 14881:2021

Overview

ISO 14881:2021 - Integrated optics - Interfaces - Parameters relevant to coupling properties defines the vocabulary and measurable parameters needed to describe how light is coupled into and out of integrated optical chips (IOC) and photonic integrated circuits (PIC). The standard concentrates on butt coupling via waveguide endfaces, providing the basis for specifying elements to be coupled (e.g., optical fibres, fibre arrays, integrated optical chips) and their coupling-related properties.

Key Topics

The document standardizes terms, measurement references and tolerances that affect coupling performance:

• Coupling efficiency and coupling loss: definitions and relationships between emitted and received optical power.
• Chip geometry: chip length, width, thickness, inclined facets, flatness and bow - specified in millimetres.
• Waveguide geometry: reference-mark position, pitch, depth below surface, and per-position tolerances (preferred pitch examples: 0.125 mm, 0.25 mm, 0.4 mm).
• Fibre tolerances: cladding/core diameter, non‑circularity, concentricity error and spot size - measured per IEC 60793-1-20.
• Endface properties: facet angles, radii, flatness, roughness (Ra measured per ISO 4288), and coatings (AR, reflective, λ/4).
• Spot size and polarization: horizontal/vertical near-field spot sizes and TE/TM mode specification (per ISO 11807-1).
• Specialized items: array blocks, V-groove arrays, fixed alignment structures, index matching and adiabatic coupling.

Practical Applications

ISO 14881:2021 is practical for anyone involved in design, manufacture, testing or procurement of integrated optics and photonic modules:

• Photonics and optical engineers specifying PIC-to-fibre coupling and optimizing butt coupling interfaces.
• Manufacturers of integrated optical chips, fibre arrays, V-groove carriers and alignment fixtures needing standard tolerances and definitions.
• Test and QA laboratories measuring coupling loss, endface roughness, spot size and alignment to ensure reproducible assembly.
• Procurement teams and systems integrators writing technical requirements for fiber-to-chip interconnects in telecom, datacom, sensing and quantum photonics systems.
• R&D teams developing low-loss couplers, AR/λ/4 coatings or adiabatic tapers for improved coupling efficiency.

Related Standards

ISO 14881:2021 references and harmonizes terminology and measurement methods with:

• ISO 11807-1:2021 and ISO 11807-2 (Integrated optics - Vocabulary)
• ISO 4288 (Surface texture profile method)
• IEC 60793-1-20 (Optical fibre geometry and measurement methods)

By adopting ISO 14881:2021, organizations can ensure clear, consistent specifications for interfaces and tolerances that directly affect optical coupling performance between fibres and photonic integrated circuits.