Diagnosing and Solving Common Optical Transceiver Failures

In the course of using optical transceivers, a variety of challenges are bound to arise. Here, it's outlined that two prevalent issues encountered with optical transceivers along with their respective solutions.

Optical Module Interconnection Precautions and Troubleshooting Guide

Interconnection Precautions

Theoretically, optical transceivers with the same interface standard type can be connected, but attention must be paid to the transceiver power range and transmission distance in practical use. The primary factors affecting the successful docking of optical transceivers are as follows:

• 1. Wavelength: Docking optical transceivers of different wavelengths is prohibited. Different wavelengths experience varying transmission loss and dispersion in the fiber, leading to different transmission distances at the same speed. Therefore, it is essential to select optical transceivers of the same wavelength for docking.

• 2. Transmission Distance: Optical transceivers require peer-to-peer use, and transceivers designed for different distances have significantly varying interface indicators. Additionally, long-distance optical transceivers are more expensive. When docking long-distance and short-distance optical transceivers, an optical attenuator must be used to avoid damage to the transceivers. It is recommended that the supported distance of the optical transceiver should be at least as long as the fiber length to ensure compatibility.

• 3. Rate: The nominal rate of the optical transceiver should match the actual link rate. It is strictly forbidden to use a low-rate optical transceiver for high-speed signals. The nominal rate of the optical transceiver must be equal to or greater than the interface rate.

• 4. Mode: The optical fiber and optical transceiver should be used in compatible pairs, i.e., single-mode optical transceivers should be used with single-mode fibers and multi-mode optical transceivers with multi-mode fibers. Mixing different modes is not permissible.

Possible Causes

• 1. Incompatibility between the optical transceiver used and the equipment

• 2. Mismatch between optical transceiver and fiber

• 3. The port is shutdown

• 4. Transmitting optical power is too low or too high

• 5. Receiving optical power is too low or too high

• 6. Mismatch between the optical transceivers docked at both ends

Troubleshooting Steps

• 1. Confirm whether the optical transceiver on the down port is compatible with the device. Common incompatibilities between modules and devices include:

  • The transceiver is not recognized by the device; it is unresponsive when inserted, and the device does not retrieve transceiver information.

  • Upon inserting the transceiver, the device displays errors such as "Not Supported," "Unknown," or "No Qualified."

  • When the transceiver is inserted, the device status light behaves abnormally, and the port cannot establish a connection.

  • The transceiver can be connected, but the displayed information is incorrect (e.g., showing as unknown SFP). The reliability of incompatible optical transceivers cannot be guaranteed and may prevent the port from coming up.

• 2. Check whether the optical transceiver and fiber match:

  • Single-mode optical transceivers (typically with wavelengths of 1310nm or 1550nm) correspond to single-mode fiber, usually yellow.

  • Multimode optical transceivers (typically with a wavelength of 850nm) correspond to multimode fiber, which can be orange, aqua blue, or rose red.

• 3. Check for alarm information related to the optical transceiver:

  • Verify if there is an LOS (Loss of Signal) alarm, indicating that no signal is being sent from the other side.

  • Ensure that the ports at both ends are not shutdown. If they are, enable them by executing the appropriate command.

• 4. View the diagnostic information of the optical transceiver:

  Check for alarm information about transmitting or receiving optical power. Verify the current transmit and receive optical power values, as well as the default maximum and minimum power values:

  • If the receiving power is low (RxPower Low), the signal received is too weak, possibly due to excessive transmission distance or fiber damage.

  • If the receiving power is high (RxPower High), the signal received is too strong, potentially because of a short transmission distance when using a long-range optical transceiver.

  • If the transmitting power is low (TxPower Low), the local optical transceiver might be faulty, leading to low receiving power at the opposite end.

  • If the transmitting power is high (TxPower High), the signal is too strong, which might damage the optical transceiver at the opposite end due to high receiving power.

  After successfully docking the optical transceiver, check for any alarms regarding transmitting or receiving optical power to avoid issues related to abnormal power levels.

• 5. If there are no alarms and the port is still not up:

  • Capture the optical transceiver details and logs.

  • Replace the fiber or optical transceiver to see if the connection can be established. If the connection works with the new components, the original fiber or optical transceiver is faulty. Replace the faulty components. If the issue persists, contact technical support staff.

The Main Causes of Optical Transceiver Failure and Protective Measures

Optical transceivers must be operated standardized to avoid hidden damage or permanent failure. Any irregular actions can lead to transceiver issues.

The Main Causes

The primary causes of optical transceiver failure are performance degradation due to ESD (Electrostatic Discharge) damage and optical link failure caused by optical port contamination and damage. Key reasons for optical port contamination and damage include:

• 1. Exposure to the Environment: The optical port of the transceiver becomes contaminated by dust entering the port when exposed.

• 2. Polluted Fiber Connector End Face: The end face of the fiber connector can be contaminated, leading to secondary contamination of the optical transceiver port.

• 3. Improper Use of Optical Connectors: This includes scratches on the end face or other improper handling of the pigtail connectors.

• 4. Poor Quality Fiber Optic Connectors: Using substandard connectors can lead to contamination and damage.

Effective Protective Measures

ESD Protection

ESD damage is a significant issue that can deteriorate optical device performance or even result in a loss of optoelectronic function. ESD-damaged optical devices are challenging to test and screen, making it difficult to quickly locate failures.

Instructions:

• 1. Optical transceivers must remain in anti-static packaging during transportation and handling before use, and should not be removed or placed randomly.

• 2. Wear anti-static gloves and bracelets before handling optical transceivers, and take anti-static measures when installing optical devices.

• 3. Ensure test equipment or application equipment has a proper grounding wire.

Physical Protection

The laser and temperature control circuit (TEC) inside the optical transceiver are fragile and can easily break or dislodge after impact, necessitating careful handling during transportation and use.

Instructions:

• 1. Handle the optical transceiver with care to prevent dropping or impact.

• 2. When inserting the optical transceiver, avoid using metal tools. Instead, open the pull ring to the unlocking position before pulling, avoiding using other tools.

• 3. Clean the optical port with special cleaning tools provided by FS, avoiding using metal substances that can damage the optical po

Conclusion

In this article, we discuss the main reasons and solutions for optical transceiver connection failures, which may help you with diagnosing common module issues. To minimize the chances of issues, high-quality modules are recommended. FS offers high-quality modules that have been rigorously tested in professional laboratories, significantly enhancing stability and reliability. Moreover, FS customers benefit from 24*5 expert online support provided by a dedicated IT team. Check out FS optics and transceivers and choose the optics you need.