Eclipse Versus Conventional Optical Choppers: Modeling and Analysis

Optical choppers with rotational disks are a common component of photonic and optoelectronic systems. They are utilized as optical modulators, for example for the controlled attenuation of light or for generating laser impulses of different profiles and frequencies. While commercially-available choppers have disks with windows with linear margins, we have proposed and patented chopper disks with windows with non-linear (in particular semi-circular), inward- or outward-oriented margins. Because of the way the laser beam is obscured in this case, similarly to a planetary eclipse, we have proposed for the latter devices the term of eclipse choppers, which was accepted by the community. An analytical, as well as a numerical modeling of the devices has been completed. The optical functions of both variants have been deduced and they are analyzed in a comparison between eclipse and conventional choppers – for top-hat (incident) laser beams. An insight in using Gaussian beams is also made. We demonstrate the advantages of eclipse choppers in light modulation, as well as how the characteristic functions of these novel devices are the general case of conventional devices. Also, while commercially-available, macro-devices have rotational disks, we discuss how such choppers can be built as MEMS (with oscillatory elements), in order to increase compactness – for a better integration in photonic systems.