Optical frequency doubling, also known as second harmonic generation, is a nonlinear optical process where a photon with a specific frequency interacts with a nonlinear material to produce a new photon with double the frequency. This results in light that has a shorter wavelength, effectively shifting the color of the light towards the blue end of the spectrum. This technique is commonly used in various applications, including laser technology and solid-state lighting. By converting infrared light into visible light, optical frequency doubling enhances the efficiency and performance of devices like lasers and LEDs, making them more versatile for different uses.