indices = [0,1,4,7]
for i,bias,spectrum in zip(range(len(biases)),biases,transmission_spectra):
if i in indices:
x = spectrum.energies().inUnitsOf(eV)
y = spectrum.spectralCurrent().inUnitsOf(Units.A/eV)
pylab.plot(x, y*1.e3, label="%.1f V" % bias)