IEC 61977:2020

Overview

IEC 61977:2020 - Fibre optic interconnecting devices and passive components - Fibre optic fixed filters - Generic specification - is the fourth edition of the IEC generic specification for fibre optic fixed filters. It defines the family of passive, non‑tuneable optical filters that modify spectral intensity to select or suppress wavelengths and that interface via optical fibres or fibre connectors. The standard establishes uniform requirements for optical, mechanical and environmental properties and provides the terminology used in related IEC 61753‑04x documents.

Key topics and technical requirements

This generic specification covers classification, documentation and testable performance of fibre optic fixed filters:

• Filter categories: short‑wave pass, long‑wave pass, band‑pass, notch, and gain‑flattening filters (including hybrid/combinations).
• Passive and fixed operation: filters contain no optoelectronic transducers and are not tunable.
• Interfaces: input/output or common ports via optical fibre or optical fibre connectors.
• Requirements and clauses (high level):
  • Classification and interface styles
  • Documentation (drawings, symbols, instructions for use)
  • Tests and measurements, and test reporting
  • Design and construction: materials and workmanship
  • Quality assurance and reliability considerations
  • Identification, marking, packaging, storage and safety
• Performance descriptors: insertion loss, passband ripple, stopband characteristics, X dB bandwidth and similar spectral metrics (illustrated in the standard’s figures).
• Edition changes: this 2020 revision refocuses scope on fixed filters, adds new terms, removes duplicated definitions, harmonizes figure axes and restructures Clause 4 to reflect market and technical evolution.

Practical applications

IEC 61977:2020 is directly applicable where fixed spectral control in fibre networks or devices is required:

• Passive wavelength selection for DWDM/CWDM modules, multiplexers and demultiplexers
• Gain flattening modules for fibre amplifiers (EDFAs) to equalize spectral gain
• Notch or band‑pass filtering in sensing, instrumentation and measurement systems
• Stabilizing pump/laser wavelengths or protecting subsystems from unwanted spectral components

Practical benefits include consistent test methods, clear product classification for procurement, and standardized documentation that reduces integration risk in optical communications and passive component manufacturing.

Who should use this standard

• Component and subsystem manufacturers (design & quality teams)
• Test laboratories and QA organizations that perform optical and environmental testing
• Systems integrators and network equipment vendors specifying passive optical filters
• Procurement and compliance teams seeking uniform acceptance criteria

Related standards

• IEC 61753‑04x series (terminology and performance specifications referenced in the bibliography)
• IEC 63032 (for tuneable bandpass filters) - IEC 61977 focuses specifically on fixed filters

Keywords: IEC 61977:2020, fibre optic fixed filters, fibre optic filters, passive components, band‑pass filter, notch filter, gain flattening, optical fibre connectors, insertion loss, DWDM.