Bassam A. Saadany

Ultra-compact MEMS FTIR spectrometer

Portable and handheld spectrometers are being developed and commercialized in the late few years leveraging the rapidly-progressing technology and triggering new markets in the field of on-site spectroscopic analysis. Although handheld devices were commercialized for the near-infrared spectroscopy (NIRS), their size and cost stand as an obstacle against the deployment of the spectrometer as spectral sensing components needed for the smart phone industry and the IoT applications. In this work we report a chip-sized microelectromechanical system (MEMS)-based FTIR spectrometer. The core optical engine of the solution is built using a passive-alignment integration technique for a selfaligned MEMS chip; self-aligned microoptics and a single detector in a tiny package sized about 1 cm3. The MEMS chip is a monolithic, high-throughput scanning Michelson interferometer fabricated using deep reactive ion etching technology of silicon-on-insulator substrate. The micro-optical part is used for conditioning the input/output light to/from the MEMS and for further light direction to the detector. Thanks to the all-reflective design of the conditioning microoptics, the performance is free of chromatic aberration. Complemented by the excellent transmission properties of the silicon in the infrared region, the integrated solution allows very wide spectral range of operation. The reported sensor’s spectral resolution is about 33 cm-1 and working in the range of 1270 nm to 2700 nm; upper limited by the extended InGaAs detector. The presented solution provides a low cost, low power, tiny size, wide wavelength range NIR spectral sensor that can be manufactured with extremely high volumes. All these features promise the compatibility of this technology with the forthcoming demand of smart portable and IoT devices.

Analysis of Novel Building Blocks for Photonic MEMS Based on Deep 1D Photonic Crystals

This papers deals with the study of novel building blocks suitable for architectures of MEMS tunable lasers integrated in SOI platforms. These building blocks are based on the use of 1D photonic crystals (1D PCs) made of silicon-air thin layers stacks. These provide high reflectivity in certain wavelength range as well as access to simple Fabry-Perot cavities. The latter was studied more in detail and simulations are presented along with preliminary experimental results. A tilted Fabry-Perot cavity was analyzed for its potential of mode selector to prevent for mode hopping and thus enable continuous mode tuning by control of separation gap. As 1D PCs exhibit dispersion characteristics, this behavior is analyzed as well for its potential use for compensation purposes of wavelength dependence of the refractive index in the III-V gain medium.