Since 2020, aggregated from related topics
Difference frequency generation (DFG) is a nonlinear optical process in which two input laser beams of different frequencies are combined in a nonlinear crystal to generate an output beam with a frequency equal to the difference between the two input frequencies. This technique is commonly used in a variety of applications such as spectroscopy, metrology, and communication systems. DFG is particularly useful for generating tunable, coherent light in the mid- to far-infrared spectral regions where traditional laser sources are limited. The process relies on the nonlinear optical properties of the crystal material and requires precise control of the phase-matching conditions to achieve efficient frequency conversion.