An UV linear variable optical filter-based micro-spectrometer

This paper presents the design, fabrication and spectral measurements of an Ultra-Violet (UV) Linear Variable Optical Filter (LVOF)-based micro-spectrometer operating in the 300 nm–400 nm wavelength range. The UV LVOF has been fabricated in an IC-Compatible process using resist reflow. Characterization by passing monochromatic light through the LVOF, shows high linearity of the profile. It is expected that using signal processing, spectral resolution better than 0.5 nm can be achieved with this UV LVOF. The filter provides the possibility to have a robust high-resolution micro-spectrometer in the UV on a CMOS chip.MicroelectronicsElectrical Engineering, Mathematics and Computer Scienc

Spectral measurement using IC-compatible linear variable optical filter

This paper reports on the functional and spectral characterization of a microspectrometer based on a CMOS detector array covered by an IC-Compatible Linear Variable Optical Filter (LVOF). The Fabry-Perot LVOF is composed of 15 dielectric layers with a tapered middle cavity layer, which has been fabricated in an IC-Compatible process using resist reflow. A pattern of trenches is made in a resist layer by lithography and followed by a reflow step result in a smooth tapered resist layer. The lithography mask with the required pattern is designed by a simple geometrical model and FEM simulation of reflow process. The topography of the tapered resist layer is transferred into silicon dioxide layer by an optimized RIE process. The IC-compatible fabrication technique of such a LVOF, makes fabrication directly on a CMOS or CCD detector possible and would allow for high volume production of chip-size micro-spectrometers. The LVOF is designed to cover the 580 nm to 720 spectral range. The dimensions of the fabricated LVOF are 5×5 mm2. The LVOF is placed in front of detector chip of a commercial camera to enable characterization. An initial calibration is performed by projecting monochromatic light in the wavelength range of 580 nm to 720 nm on the LVOF and the camera. The wavelength of the monochromatic light is swept in 1 nm steps. The Illuminated stripe region on the camera detector moves as the wavelength is swept. Afterwards, a Neon lamp is used to validate the possibility of spectral measurement. The light from a Neon lamp is collimated and projected on the LVOF on the camera chip. After data acquisition a special algorithm is used to extract the spectrum of the Neon lamp.Department of ME/EIElectrical Engineering, Mathematics and Computer Scienc