In this work, we report on the structural and optical properties of novel Ag 0.98Cu 0.02GaGe 3Se 8 single crystals that were synthesized by the Bridgman–Stockbarger technique. We have performed illumination by 10.6 μm CO 2 pulsed laser working in the microsecond time duration regime. Such illumination allows causing substantial changes for both pure electronic nonlinear optical effects like optical second harmonic generation as well as piezooptical effects described by the fourth rank tensors. The measurements of the piezo-optical effects were carried out at different temperatures. The effects are observed only during the IR CO 2 laser illumination and are disappeared after switching off the illumination. Simultaneously the IR induced optical second harmonic generation at Er:glass laser fundamental wavelength 1540 nm was performed during illumination by nanosecond Nd:YAG and Er 3+:glass laser. The observed effects allow to use the studied materials as promising for IR-optoelectronic devices.