Femtosecond Nonlinear Coherence Spectroscopy of the Blue Band of GaN

The nonlinear optical properties of an undoped GaN epitaxial layer have been investigated in the spectral region 400 - 450 nm using two-colour multiple-pulse photon echo measurements. Variation of the laser wavelengths and pulse sequence and the use of spectrally resolved measurements allows us to study the dephasing of the donors and acceptors and the energy relaxation properties for the blue band of GaN