Commissioning Optical Power of OTU Board

The overload of the APD receiver laser is -9 dBm. If the input optical power is higher, the APD laser may be damaged. Therefore, it is recommended that you insert the fiber loosely from the input optical port of the OTU during commissioning. After commissioning, make sure the input optical power is lower than the receiver overload before you insert the fiber.

Forcing the OTU Board to Emit Light

This section describes how to force the OTU board to emit light.

Prerequisites

The NE must be created on the U2000.

Tools, Equipment, and Materials

U2000

Background Information

The signals accessed on the client side or the WDM side should be service signals in actual transmission, or the optical signals generated by forcing the board to emit light.

The WDM side of the OTU board by default is forced to emit light. If it does not emit light, refer to the following procedure to query whether the board is forced to emit light. If the board is not forced to emit light, set the board to emit light.

Precautions

• The prerequisite for commissioning the ESC (Electric Supervisory Channel) is that the OTU is forced to emit light.

Procedure

1. In the NE Explorer window, select the desired OTU and choose Configuration > WDM Interface from the Function Tree.
2. Select Channel from the drop-down list.
3. Optional: Click the Basic Attributes tab. Set the Automatic Laser Shutdown of the optical port on the WDM side of the OTU to DISABLE.
   Only the LWX2, LWXD and LWXS can set Automatic Laser Shutdown of the WDM side.
4. Set the Laser Status of the optical port on the WDM side of the OTU to OPEN.
5. Click Apply.

Adjusting the Input Optical Power of OTU Board

ools, Equipment, and Materials

Optical power meter

Precautions

Before the equipment is powered on, verify that the fixed optical attenuator is configured according to the configuration rules. Verify the input optical power of the OTU (including the WDM side and client side) is lower than the receiver overload to avoid damage to the optical module during commissioning. Note that the overload of the APD receiver laser is only -9 dBm. Adjust the input optical power at the IN port on the WDM side of the OTU to ensure that the input optical power is within the optimal range: from -14 dBm to -25 dBm.For the specifications about the sensitivity and overload point of the OTU board.

Commissioning Requirements

• Adjust the input optical power at the IN port on the WDM side of the OTU to ensure that the input optical power is within the optimal range: from -12 dBm to -5 dBm; adjust the input optical power at the RXn port on the client side of the OTU to ensure that the input optical power is within the optimal range: from (sensitivity +3) dBm to (overload point -2) dBm.
• Confirm the optical preamplifier on the WDM side of the OTU at the receive end has output the standard optical power of single wavelength. When this occurs, the input optical power on the WDM side can be adjusted based on the actual optical power by adding, changing or removing the fixed optical attenuators.
• After commissioning, insert a fiber into the input optical port on the OTU when the input optical power reaches a normal state.