Second-Harmonic Generation (SHG) is a nonlinear optical process where two photons of the same frequency interact with a nonlinear material to produce a new photon with double the energy, and thus, half the wavelength. This phenomenon is commonly observed in crystals like beta barium borate (BBO) and potassium titanyl phosphate (KTP), which are used in various laser applications. SHG is widely utilized in laser technology to generate new wavelengths, such as converting infrared light into visible light. This process is essential in fields like telecommunications, medical imaging, and spectroscopy, enhancing the capabilities of optical devices and expanding their applications.