# Change of refractive index using semiconductor

I was wondering, if it is possible to change the refractive index of a semiconductor using an electric field or current? I have heard about injecting charges to tune the refractive index. How/Why does it work and do you know how much the refractive index can be change? Also, is it reversible?

(I am very new to this topic)

• Part of the index of refraction will be from the free carriers in the material. If you want more free carriers, you inject them. For example, in a diode with no bias, the carrier concentrations in the depletion region are quite small (say $10^{11}$). In forward bias (conducting) the carrier concentrations are much higher (say $10^{17}$). – Jon Custer Jun 1 '18 at 13:37
• @JonCuster That is very interesting. Do you know the range by how much the refractive index can be changed ? – james Jun 1 '18 at 19:38
• See, for example, aip.scitation.org/doi/10.1063/1.328298 - it isn't much! – Jon Custer Jun 1 '18 at 19:47