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
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
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
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 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
APR engagement occurs in less than 500 ms after disconnection
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.