fiber.raman_on_off_gain

raman_on_off_gain(
    length_km: Annotated[float, exclusiveMinimum=0],
    *,
    pump_power: Annotated[float, minimum=0, units='W'] = 0.0,
    efficiency: Annotated[float, minimum=0, units='1/(W·km)'] = 0.4,
    pump_attenuation: Annotated[float, minimum=0, units='dB/km'] = 0.25,
) -> float

Undepleted-pump on/off Raman gain, in dB.

$$\begin{gathered} G_{\rm on/off} = \exp\!\left(C_R P_p L_{\rm eff}\right) \\ L_{\rm eff} = \frac{1 - e^{-\alpha_p L}}{\alpha_p} \end{gathered}$$

Note $L_{\rm eff}$ uses the pump’s attenuation, not the signal’s. Independent of pumping direction, which is why the direction is chosen for noise rather than for gain.

Args

• length_km: Span length, in km.
• pump_power: Pump power, in W.
• efficiency: Raman gain efficiency, in 1/(W km).
• pump_attenuation: Fibre loss at the pump, in dB/km.

Returns

On/off gain in dB.