Near- and mid-IR microspectrometers based on Linear-Variable Optical Filters

This paper presents the design, fabrication and characterization of Infra-Red (IR) Linear Variable Optical Filter (LVOF)-based micro-spectrometers. Two LVOF microspectrometer designs have been realized: one for operating in the 1400 nm to 2500 nm wavelength range and another between 3000 nm and 5000 nm. The IR LVOF has been fabricated in an IC-Compatible process using resist reflow. The LVOF provides the possibility to have a small size, robust and high-resolution micro-spectrometer in the IR on a detector chip. Such IR microspectrometers can be fabricated at low-cost in high volume production and have huge potential in applications such as liquid identification (e.g. water in alcohol, water in oil) and gas sensing.