This article describes a new invention by NIST called the cavity buildup dispersion spectrometer. It uses a special setup involving a shutter, frequency shifter, and resonator to measure changes in light as it passes through a material. The device detects tiny changes in the motion of the resonator or the refractive index of the material being studied. It does this by measuring a beat frequency in the light, which provides information about both the absorption and dispersion of the material in a single measurement.
Unlike traditional methods that require multiple steps or extra equipment, this invention uses just one laser beam and controls its frequency and power to get accurate results. This makes the process simpler and more precise, avoiding common issues like noise and measurement bias. The technology could be used in various fields, such as sensing the refractive index of gases, studying materials, or measuring physical changes like pressure or movement. The device is designed to be easy to use and could be commercialized by companies that specialize in optical instruments.
Keywords: quantum metrology, optical resonator, refractive index sensing
