We report the characteristics of cavity polaritons in a CuBr microcavity consisting of a λ/2-thick CuBr active layer and HfO<Subscript>2</Subscript>/SiO<Subscript>2</Subscript> distributed Bragg reflectors: λ corresponds to an effective resonant wavelength of the lowest-lying exciton. The excitonic system of a CuBr crystal has three kinds...</subscript></subscript>

We have investigated electric field strengths in the Al<Subscript>x</Subscript>Ga<Subscript>1-x</Subscript>N layer, F<Subscript>AlGaN</Subscript>'s, of Al<Subscript>x</Subscript>Ga<Subscript>1-x</Subscript>N/GaN heterostructures with and without a GaN cap layer using photoreflectance (PR) spectroscopy. Franz-Keldysh oscillations (FKOs) from the Al<Subscript>x</Subscript>Ga<Subscript>1-x</Subscript>N layer are clearly observed in the PR spectra. It is...</subscript></subscript></subscript></subscript></subscript></subscript></subscript>