Optical nonlinearities in CdTe quantum-dot doped glass for optical switching

We have studied the nonlinear absorption and refractive index in CdTe quantum dots in glass. We find that the nonlinearities differ from those of bulk CdTe. An ultrafast polarization-rotation switch with on-off ratio of 42:1 is demonstrated. We showed that quantum confinement lowers the two-photon absorption coefficient and raises the nonlinear refraction index, both of which are good for all-optical switching devices.