def __init__(self, wavelen, duration, power, efficiency):
self.wavelen = wavelen
self.duration = duration
self.power = power
self.efficiency = efficiency
self.effective_power = power * efficiency
self.effective_pump_rate = energy.photon_count(wavelen, self.effective_power)
def _rate(self, inversion):
# at zero inversion, depopulation rate is undefined but approaches zero
if inversion == 0.0:
return 0.0
active_medium = self.active_medium
doping_agent = active_medium.doping_agent
active_solid_angle = active_medium.active_solid_angle
ln_gain = doping_agent.xsection * inversion * active_medium.length
gain = math.exp(ln_gain)
intensity = self._saturation_intensity * (active_solid_angle/4.0) * (gain-1.0)**1.5/(gain*ln_gain)**0.5
power = 2.0 * active_medium.aperture * intensity
rate = energy.photon_count(doping_agent.lasing_wavelen, power)
# fluorescence in directions outside of the two active solid angles:
rate += (1.0 - 2.0 * active_solid_angle / (4.0 * math.pi)) * self._decay_rate(inversion, doping_agent.laser_transition_probability)
# fluorescence to other states:
rate += self._decay_rate(inversion, doping_agent.nonlaser_transition_probability)
return rate