# Nominal single-wavelength input optical power for OA boards on BWS 1600G?

Suggestion:
What is the nominal single-wavelength input optical power is determined for OA boards of the BWS 1600G? Answer:
Strictly speaking, there is no definition of nominal single-wavelength optical power for OA boards. The optical power is determined as follows:
To increase the signal-to-noise ratio, the incident optical power and receive optical power must reach the maximum as possible.
A 400G OAU board is used as an example.
The maximum incident optical power is 20 dBm and 40 wavelengths are supported. Therefore, the maximum single-wavelength output optical power is 4 dBm.
The BA gain is 19 dB, and therefore the single-wavelength input optical power of the BA board is defined to -15 dBm.
A VOA and DCM need to be added between PA and BA boards, the minimum VOA attenuation is 3 dB, and the maximum DCM attenuation is 12 dBm. Therefore, the minimum single-wavelength output optical power of the PA board is as follows: -15 + 12 + 3 = 0 (dBm).
The C-band gain is 20 dB and the L-band gain is 19 dB, and therefore the maximum single-wavelength input optical power of the PA board is -19 dBm.
The attenuation of the maximum span is 36 dB, and therefore the minimum single-wavelength input optical power of the PA board is as follows: 4 - 36 = 32 (dBm).
Varying with span reaches, the single-wavelength input optical power of the PA board ranges from -32 dBm to -19 dBm. The gain of a PA board embedded with a Raman amplifier (OAU_R) is 10 dB, and therefore the single-wavelength input optical power is -9 dBm.