Project B02 continues with the fabrication of cubic GaN/Al(Ga)N heterostructures and the investigation of their ultrafast and/or nonlinear optical properties. In the second period, we aim to enlarge and utilize the resonant nonlinearity associated with near-infrared intersubband transitions in quantum wells. This will be achieved by stronger doping and growth of structures with spectrally narrower resonances. In addition, we will investigate nonlinear metasurfaces formed by depositing antenna structures resonant to the intersubband transitions. Such structures massively enhance the optical nonlinearity and enable nonlinear optical frequency mixing with relaxed phase-matching conditions.