Overview
IEC 62150-4:2009 - "Fibre optic active components and devices - Test and measurement procedures - Part 4: Relative intensity noise using a time-domain optical detection system" - defines standardized procedures to measure relative intensity noise (RIN) of lasers, laser transmitters and the transmitter portion of transceivers. The standard is targeted at single longitudinal mode (SLM) sources and describes a time-domain optical detection method that yields a single RIN value averaged over the transmission bandwidth. An optional controlled return-loss setup is included for devices coupled to single-mode fibre (SMF).
Key topics and requirements
- Scope: measurement procedures for RIN for lasers, transmitters and transmitter modules (SLM only).
- Measurement approach: time-domain optical detection system composed of an optical‑to‑electrical (O/E) converter, linear‑phase low‑pass filter and oscilloscope to capture intensity vs. time.
- Calibration: procedures to remove photodetector dark current and account for frequency response (references IEC 62007-2, IEC 61280-2-2).
- Optional controlled return loss subsystem: polarization controller, single‑mode coupler, variable optical attenuator (VOA) and fixed reflector to present a controlled return loss for SMF-coupled devices.
- Outputs: a single averaged RIN value over the transmission bandwidth and the alternative RIN_OMA definition (per IEEE 802.3-2005) for square‑wave modulated sources.
- Alternative method: photoreceiver plus electrical spectrum analyzer to obtain RIN vs. electrical frequency (averaged over a filter bandwidth representative of a system).
- Noise handling: the described method measures total intensity noise and does not attempt to subtract thermal and shot noise.
- Notes: Annex A provides background on laser intensity noise; a patent notice is included regarding an FFT-based signal/noise separation method in clause 5.4.2.
Applications and who uses this standard
- Component manufacturers and module/transceiver designers validating laser transmitter performance.
- Test laboratories and quality assurance teams performing production or conformance testing.
- System engineers assessing the impact of laser intensity noise on signal‑to‑noise ratio (SNR), bit error rate (BER) and power budgeting in analogue or digital links.
- R&D groups characterizing SLM laser noise behavior and sensitivity to back reflections (return loss).
Practical uses include transmitter qualification, troubleshooting excess noise, production acceptance tests, and ensuring compatibility with system filtering (e.g., ITU‑T G.957 requirements).
Related standards
- IEC 62150 series (other parts)
- IEC 61280-2-2 (optical eye pattern, waveform)
- IEC 61300-3-6 (return loss)
- IEC 62007-2 (O/E calibration methods)
- IEEE 802.3-2005 (RIN_OMA definition)
- ITU‑T G.957 (frequency response for transmission rates)
Keywords: relative intensity noise (RIN), single longitudinal mode (SLM), time-domain optical detection, laser transmitter testing, IEC 62150-4:2009.