Multimode interference (MMI) devices in silicon hollow waveguide technology for military electro-optic systems

Abstract

Component alignment slots and low attenuation hollow waveguides formed in silicon substrates by standard DRIE etching techniques provide the optical analogue of the electronic printed circuit board. In conjunction with conventional pick-and-place equipment this new hybrid integration technology will facilitate low cost mass production of compact, rugged, electro-optic microsystems for military platforms. In addition to the integration of discrete components (lasers, modulators, detectors, wave-plates etc) monolithic components are also feasible. These include: (i) the analogues of free space components - plane and curved mirrors, polarization splitters, diffraction gratings, MEMS devices for beam steering etc, and, (ii) hollow waveguide components - tapers for mode matching, proximity couplers, waveguide attenuators, and, a range of multimode interference (MMI) devices. MMI devices are attractive in that they offer a wide range of optical functionality from simple geometric structures, these include intensity and wavelength splitters and mixers. In this context the military efficacy of the technology is highlighted in the demonstration of a novel form of waveguide spectrometer for a new generation of hyperspectral sensors.