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After we buy the optical power attenuators, we may help to know how is the quality, is it bad or good? This article will briefly introduce the test key parameters and methods, hope it will help.
I. Key Performance Parameters
- Attenuation Range: Must cover actual needs (e.g., 0.3~60dB). Variable attenuators must support dynamic adjustment (e.g., 0-40dB).
- Insertion Loss: Fixed attenuators should be ≤0.35dB, VOA attenuators should be ≤1.0dB (high quality) or ≤3.0dB (standard).
- Return Loss: Single-mode >55dB, multi-mode ≥18dB, to reduce reflection interference.
- Operating Wavelength: Single-mode commonly uses 1310nm/1550nm, multi-mode can use 850nm/980nm.
- Power Handling: Must be higher than the system’s optical power (e.g., 500mW).
II. Test Methods
- Reference Method: Measure the optical power of the reference link (P₁), then measure the output power (P₂) after connecting the attenuator under test. The insertion loss L = P₁ – P₂.
- Substitution Method: Replace the patch cord in the reference link with the attenuator and compare the power difference.
- Dynamic Testing: Use a digital communication analyzer to test the response speed and stability of the attenuator.
III. Precautions
- Environmental calibration: The equipment needs to be preheated before testing to ensure stable temperature and humidity.
- Repeated measurements: Data should be recorded after each setting has stabilized for 30 seconds, and the average value should be taken.
- Tool selection: It is recommended to use a high-precision optical power meter or a handheld adjustable attenuator.
