raman_on_off_gain

photonforge.fiber.raman_on_off_gain(length_km, *, pump_power=0.0, efficiency=.4, pump_attenuation=0.25)

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

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

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.

Parameters:

• length_km (Annotated[float, exclusiveMinimum=0]) – Span length, in km.

• pump_power (Annotated[float, minimum=0, units='W']) – Pump power, in W.

• efficiency (Annotated[float, minimum=0, units='1/(W·km)']) – Raman gain efficiency, in 1/(W km).

• pump_attenuation (Annotated[float, minimum=0, units='dB/km']) – Fibre loss at the pump, in dB/km.

Returns:

On/off gain in dB.

Return type:

float