Profile: Sabeus, Inc. specializes in fiber optic sensing solutions for rugged environments. Our systems are comprised of interrogators, fiber optic cables, and various sensor elements. Our Field Sense™ systems are used in oil & gas industries to permanently measure sub-surface pressure, temperature, and strain, in order to optimize oilfield production & improve equipment maintenance schedules. Our gain flattening filters (GFFs) are ultra-precise long-period grating (LPG) filters based on our wavelength selectivity technology. It is designed for EDFA and Raman amplifiers. They are the ideal solution for control of non-uniform gain across optical channels of differing wavelengths. Our long-period fiber grating (LPFG) based GFFs can be custom designed to provide spectrally selective loss by coupling light from a guided mode into forward propagating cladding modes where it is lost due to absorption and scattering. The coupling from the guided mode to the cladding modes is wavelength dependent providing spectrally selective loss. The LPFG is an intrinsic optical fiber structure with optical properties periodically varying along the fiber, such that the conditions for the interaction of several co-propagating modes are satisfied.