Will the laser in a broken optical fiber harm us?

Optical fiber is an important component of communication transmission. When the optical fiber breaks, if the output optical power of the optical amplifier board is not weakened in time, the laser leaked from the break will burn or even blind the human eye (optical power is greater than 10 dB).

Don't worry, there is a function in the transmission system that is responsible for reducing the laser light power to a safe level when the optical fiber is broken. The name of this function is APR-AOSD group (Automatic Power Reduction - Auto Optical Shutdown Group).

When the optical cable fails, the APR-AOSD group function automatically starts, reducing the output optical power of the optical amplifier board in the OTS (Optical Transmission Section) to a safe level, thereby preventing laser damage to the human body. When the optical cable is repaired, the system restores the optical amplifier board to normal working state.

1. Key components of the APR-AOSD group

The APR-AOSD group consists of a controller, a monitor, and an actuator. When the optical cable fails, the monitor reports an input no-light alarm to the controller, and the controller sends a laser shutdown command to the actuator, which ultimately shuts down the laser of the optical amplifier board.

2. APR-AOSD group workflow

Let's take a closer look at the workflow of the APR-AOSD group in the networking scenario:

• The optical signal continuity loss is detected at the receiving port R2 of the monitor OA2 and reported to the controller.
• The controller sends a laser off command to the actuator OA3, and the actuator OA3 turns off the laser.
• The optical signal continuity loss is detected at the receiving port R1 of the monitor OA4 and reported to the controller.
• The controller sends a laser off command to the actuator OA1, and the actuator OA1 turns off the laser.

This whole process ensures that the optical power in the OTS segment where the fault occurs is at a safe level, thus avoiding the harm of strong laser to the human body.

3. APR-AOSD group recovery mechanism

When the optical cable is repaired, the APR-AOSD group function can restore the service to normal operation through its own automatic restart recovery mechanism. The specific process is as follows:

• The system automatically increases the optical power transmitted by the T1 port to a reasonable level at regular intervals, which can ensure safety and ensure that the monitor can still identify it after attenuation.
• If the fiber fault has been repaired, the receiving port R2 is no longer in the LOC-OTS state, so the signal of the T2 sending port is restored to the normal working state, that is, the system restores OA3 to the normal working state.
• When the signal at the T2 sending port returns to normal, the receiving port R1 is no longer in the LOC-OTS state, and thus the signal at the T1 sending port returns to a normal working state.

What if the fiber is not restored during the signal transmission restart of T1? Then the LOC-OTS state at R2 cannot be released, and the signal transmission of T1 is reduced to the safe power again and enters the next automatic restart process.

In this way, the entire system resumes normal transmission.

The above is all about the APR-AOSD team~ The lovely communicators ensure the smooth flow of the network, and our APR-AOSD team silently protects our communicators!