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TCX1000 Automatic Laser Shutdown


This topic describes how the automatic laser shutdown safety mechanisms work on TCX1000 devices.

TCX1000 Automatic Laser Shutdown Overview

Due to the potential safety hazard that is posed by the high power optical outputs, the TCX1000-RDM20 and TCX1000-ILA have an automatic laser shutdown (ALS) mechanism that guards against the risk of direct human exposure to high-powered lasers.

ALS applies only to Line Out port connections between adjacent TCX1000 devices. The ALS mechanism acts to detect a fiber disconnection or fiber cuts along the span, and upon doing so, causes the shutdown of the high-powered WDM composite signal.

This topic discusses the automatic laser shutdown (ALS) mechanisms on the TCX1000-RDM20 and TCX1000-ILA.


The ALS mechanisms discussed here apply to the Line Out ports on interconnected TCX1000 devices including:

  • TCX1000-RDM20 to TCX1000-RDM20

  • TCX1000-RDM20 to TCX1000-ILA

  • TCX1000-ILA to TCX1000-ILA

Automatic Line Shutoff

Automatic line shutoff is one of the main safety mechanisms on TCX1000-RDM20 and TCX1000-ILA. Automatic line shutoff is implemented on the Line Out ports of the TCX1000-RDM20 and TCX1000-ILA. Automatic line shutoff identifies fiber breaks or disconnects between two interconnected TCX1000 device Line Out ports.

Table 1 describes the automatic line shutoff logic for the TCX1000-RDM20 and the TCX1000-ILA:

Table 1: Automatic Line Shutoff Logic for TCX1000-RDM20 and TCX1000-ILA

Automatic line shutoff





Line In LOS is true + OSC link state is down

If this condition is true, on the TCX1000-RDM20, the line output power on the TCX1000-RDM20 is automatically disabled.

If this condition is true, on either Line In port on the TCX1000-ILA, the line output power is automatically disabled on both Line Out ports.



Line In LOS is false


OSC link state is up and OSC In LOS is false

Line output power on the TCX1000-RDM20 or TCX1000-ILA is normal under this condition.

TCX1000-RDM20 Automatic Power Reduction

On the TCX1000-RDM20, automatic power reduction (APR) of the booster is triggered if the reported output return loss (ORL) is less than 17 dB. Normal operation resumes when the ORL exceeds 20 dB. APR limits output power to +3 dBm regardless of current provisioned settings and input power. It does not prevent operating at lower output powers. The primary intent of APR is to reduce output power to eye safe levels in the event the Line Out fiber is disconnected.

APR engagement occurs in less than 500 ms after disconnection of the Line Out fiber.

TCX1000-ILA Automatic Power Reduction

On the TCX1000-ILA, automatic power reduction (APR) reduces the output power level on open line out (Line A Out and Line B Out) ports to a safe eye level. If either line output port on the TCX1000-ILA is open or becomes disconnected, the output power of the port is attenuated by 2 dB to bring it to safe level, if it is not already at safe level.


Automatic power reduction (APR) is implemented on both line output ports of the TCX1000-ILA — Line A Out and Line B Out.

The TCX1000-ILA APR mechanism monitors the back-reflection ratio (OBR) of each line output port and uses it as a gauge. If the back-reflection ratio goes above -17 dB (indicative of a fiber cut) on either output port, and the total output power is higher than 19 dBm, the amplifier enters the APR state and an APR alarm (“EDFAABRFL” or “EDFABARFL”) is raised. The amplifier stays in APR state until the back-reflection ratio goes below -19 dB, at which point the target output signal power is restored and the APR alarm is cleared.

APR engagement occurs in less than 40 ms after disconnection of either line port fiber.

TCX1000-RDM20 Output Power Clamp

Preamplifier output power is clamped to a maximum power to ensure that the output is below Class 1M limits even if the full C-band is routed out a single Ux Out port with minimum insertion loss. This apply to the universal ports on the TCX1000-RDM20. You cannot disable or adjust this clamp.