Polaritonics in nanowires made from dispersive materials

We have studied the optoelectronics of a polaritonic nanowire which is fabricated by embedding a polaritonic crystal into another polaritonic crystal. It is considered that the band gap of the embedded crystal lies within the band gap of the host crystal. This band-gap engineering is satisfied by GaP and MgO crystals where MgO is the host crystal. Polaritons in the nanowire are confined within the embedded crystal. Bound states of the confined polaritons are calculated using the transfer-matrix method. The bound polariton energies are evaluated for a GaP-MgO nanowire. It is found that the number of bound states in the wire depends on its size, well depth, and the barrier height. The absorption coefficient of the system has also been calculated by using the time-dependent Schr\"odinger equation method. Numerical simulations for the GaP-MgO nanowire show that when the resonant energy of a quantum dot lies near the bound states the spectrum has several transparent states. The nanowire can be switched among the transparent or absorbing states by tuning the resonant state of the quantum dot. The present findings can be used to make types of polaritonic devices such as polaritonic switches and transistors.