We did this work to help professors and students of physics engineering in Optics Lasers courses who require a theoretical-experimental introductory framework nonlinear optics. showed article the basic principles theory, focusing on third-order optical phenomena, using well-known Z-scan technique for its demonstration. For this, we propose design simple experiment that interested party can do a...

Schr\"odinger equation is a nonrelativistic wave equation, which does not have Lorentz invariance. Therefore, this has large theoretical error in the precise calculation of hydrogen-like system. So commonly used method Dirac-Hartree-Fock approximation atomic However, we found new eigen whose eigenvalue system approximates quantum electrodynamics. Hence, propose scheme for hyperfine structure ba...