During the use of the optical transceiver module, various problems will inevitably occur. The following summarizes the main reasons and solutions in the event of failure.

Matters needing attention before use
1. Do not connect optical modules with different wavelengths. Due to the different transmission loss and dispersion in the fiber, the transmission distance corresponding to different wavelengths at the same rate is different, so it is necessary to select optical modules with the same wavelength when connecting.
2. Since the interface specifications of optical modules vary with distance, long-distance optical modules are expensive. Therefore, an optical attenuator must be added between the long-distance optical module and the short-distance optical module. To avoid burning out the optical module, it is recommended that the distance between the optical module should not be less than the length of the optical fiber.
3. The nominal rate of the optical module must be consistent with the actual link rate. High-speed signals are not allowed to run on low-speed optical modules. The nominal rate of the optical module must be greater than the nominal rate of the interface.

4. Optical fiber and optical module must be paired. That is, single-mode optical modules use single-mode fibers, and multi-mode optical modules use multi-mode fibers.

Fault Phenomenon

The two optical ports are connected through optical fibers, the local port is Down, and the optical module connection does not work.

Possible Causes
1. The optical module used is not compatible with the device
2. The optical module does not match the fiber port is closed
3. Transmitting optical power is too low or too high
4. The received optical power is too low or too high
5. The optical modules at the two ends do not match

6. Port configuration does not match module type

Troubleshooting Procedure
1. Check whether the optical module of the Down port is compatible with the device.
2. Check whether the optical module matches the optical fiber
3. Take a Huawei switch as an example, run the display interface transceiver command to check whether there is any alarm information about the optical module under Alarminformation.

4. Run the display interface transceiver detailed information command to check the diagnostic information of the optical module, and check whether the optical module has alarm information about the transmit or receive optical power.

The main reasons for optical module failure and protective measures

Optical transceivers must operate in a standardized way. Any improper operation may result in hidden damage or permanent failure.

The main reasons for the failure of optical transceivers
The main reasons for the failure of optical modules are the performance degradation of optical modules caused by ESD damage and the failure of optical links caused by pollution and damage of optical ports. The main reasons for optical port pollution and damage are:
1. The optical port of the optical module is exposed, and the optical port is polluted by dust.
2. The end face of the optical fiber connector used is polluted, and the optical port of the optical module is polluted twice.

3. The end face of the optical connector with pigtail is misused, such as the end face is scratched.

4. Use inferior fiber optic connectors.

The effective protection of optical module failure is mainly divided into ESD protection and physical protection.
ESD protection: The optical module must be packed with anti-static before transportation and use, and must not be disassembled or placed at will. Before touching, you must wear anti-static gloves and anti-static wristbands, and take anti-static measures when installing optical components. Test equipment or application equipment must have a good ground wire.
Physical protection: The laser and temperature control circuit (TEC) inside the optical module are relatively fragile, and are easily broken or fallen off after being hit, so physical protection should be paid attention to during transportation and use. The optical port can be gently wiped with a cleaning cotton swab, but non-specialized cleaning cotton swabs may damage the optical port. Excessive force when using the cotton swab may cause the metal in the cotton swab to scratch the ceramic end face. The plugging and unplugging of the optical module is designed to simulate manual operation, and the push and pull forces are also designed to simulate manual operation. No appliance shall be used during installation and removal.