High Intensity Gamma-Ray Source (HIGS) is a Free-Electron Laser (FEL) based Compton backscattering gamma-ray source. The HIGS facility is located on the campus of Duke University and operated by Triangle Universities Nuclear Laboratory (TUNL). Currently, HIGS can produce gamma rays between 2 and 100 MeV with linear and circular polarizations. Total gamma-ray intensities can reach over 1 billion photons/second at some energies with few percent energy resolution. These characteristics make HIGS the world's most intense polarized gamma-ray source.