45 degrees reflectometry of semiconductor quantum wells

We have applied the 45 degrees reflectometry for the first the to study exc iton-polaritons in quantum wells. The 45 degrees reflectometry is a new pol arization-modulation technique, which is based on the measurement of the di fference (R-p-R-s(2)) between the p-polarization reflectivity (R-p) and the squared s-polarization reflectivity (R-s(2)) at an angle of incidence of 4 5 degrees. We show that R-p-R-s(2) spectra may provide qualitatively new in formation on the exciton-polariton modes in a quantum well. These optical s pectra turn out to be very sensitive to the zeros of the dielectric functio n along the quantum-well growth direction and, therefore, allow to identify the resonances associated with the Z exciton-polariton mode. We demonstrat e that 45 degrees reflectometry could be a powerful tool for studying Z exc iton-polariton modes in near-surface quantum wells, which are difficult to observe in simple spectra of reflectivity R-p.