High sensitivity fiber optic interferometric MEMS

#The present invention relates to generally the field of communication systems and more particularly to a high sensitivity fiber optic interferometric MEMS device.

#A significant obstacle to widespread application of optical transducers to chemical and biochemical sensors on a large scale is equipment cost and ease of use. Traditional spectroscopic and interferometric techniques widely used for both qualitative and quantitative determinations are bulky, expensive, laboratory systems requiring trained technicians for data acquisition and interpretation. On the other hand, cross-disciplinary applications of optical transducers require simple, low-cost, low-maintenance approaches technically accessible to non-specialists, with cheap disposable probes and compact associated electronics. Despite the low-cost features, it is desirable to provide sensitivities comparable to laboratory instruments to ensure accurate and reliable diagnoses.

#Although strides have been made to apply integration and miniaturization to cost reduction, key components of many optical sensor systems still employ traditional methods to achieve high resolution and sensitivity. For example, current fiber-optic spectroscopic sensors use high-dispersion spectrometers [1] to obtain high resolution. Micro-machined spectrometers have been demonstrated and offer the possibility of integrating both dispersion and detection; however, resolution is low [2]. Miniature interferometers [3] have also been demonstrated and applied to CO2 determination [4].

#For a more complete understanding of the present invention, and for further features and advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

#FIG. 1 is a schematic of one particular example embodiment of a FIMS device used in reflection mode according to the teachings of the present invention;

#FIG. 2 is one example of a configuration of an interferometric micro-sensor, comprising a fiber or waveguide Mach-Zehnder interferometer and two independent Fabry-Perot interferometers constructed according to the teachings of the present invention;

#Fiber optic systems are becoming the brick and mortar on which information systems ride. The chemical, biochemical or pressure sensors used in civilian and military applications are going to be the tentacles that feed into the information systems. Therefore, one aspect of this invention recognizes that it is important to develop a category of lightweight and environmentally stable sensors that directly interface to fiber-optic systems.

#The fiber-optic based sensors should be of high-sensitivity, flexible in design, compact, lightweight, rugged and low-cost. MEMS technology provides a mature platform in which such sensors can be constructed because MEMS uses standard integrated circuit processing techniques to implement novel, miniature structures. The ideal sensors would be MEMS devices that connect and take advantage of the fiber-optic technologies used in telecommunication systems.

#The present invention recognizes that for commercial and military applications in chemical, biochemical and pressure sensing, there is a need for a compact, low-cost, rugged, high-sensitivity probe that mates with fiber-optic systems. These challenges can best be met by merging the mature technologies of fiber optics with MEMS devices. More specifically, the FIMS device combines the MEMS-based Fabry Perot Interferometers (FPI's) with a Mach-Zehnder interferometer formed by overlapping the transmitted or reflected beam through the FPI's with the spatial mode of a single mode fiber.