Electromagnetic field profile of an excitonic polariton in a quantum wire waveguide
The refractive index related to the excitonic polariton in a GaAs quantum wire is calculated numerically. The maximum value of the real part of the refractive index is as large as 5.6 when the width of the GaAs wire is 5 nm. This large refractive index results from the large binding energy of the exciton confined in a quasi-one-dimensional structure. The electromagnetic field of the excitonic polariton transmitted in such a quantum wire structure is therefore squeezed significantly because the wavelength in the structure is reduced by the refractive index increase. The estimated full width at half-maximum (FWHM) of the light power related to the excitonic polariton is typically as small as 67 nm, although the transmission loss is fairly high. However, the transmission loss can be reduced by selecting an appropriate wavelength, while keeping the FWHM of the power profile small. These results indicate the possibility of making extremely small optical devices.