Effects of strain on electronic structure and optical properties of wurtzite GaN are studied by using generalized gradient approximation (GGA+U) under first-principles density functional theory (DFT). It shows that the bandgap decreases with increase of strain. The decrease of band gap is small as compressive strain is less than 3%. Strain has an effect on dielectric function imaginary part. With increase of strain, static dielectric constant increases and absorption coefficient decreases.

Effect of uniaxial strain on electronic structure and optical properties of zinc-blende structure of InN was investigated using first-principles based on density functional theory. It shows that both tensile and compressive strains make band gap of indium nitride decrease linearly. With increase of tensile strain, decrease amount of band gap increases; But with increase of compressive strain, decrease amount of band gap decreases. Between 4 eV and 12 eV, both tensile and compressive strains make absorption spectra of indium nitride red-shift. With increase of tensile strain, decrease amount of absorption spectra increases. But with increase of compressive strain, decrease amount of absorption spectra decreases. In same range of energy, refractive index and reflectivity of indium nitride increase with increase of tensile strain. But refractive index and reflectivity decrease with increase of compressive strain. As tensile strain is applied, peak value of energy loss increases. As compressive strain is applied, peak value of energy loss decreases. Electrical structure and optical properties of indium nitride can be controlled effectively by uniaxial strain.