Integrated optical fluid sensor in glass

New solutions are required for short-range optical transmission without lithography due to the complex and inflexible manufacturing processes. Glass is an excellent material for optical applications. Still, few microprocessing technologies are available, which are limited in precision and design freedom. A new glass micromachining process called Laser Induced Deep Etching (LIDE) can accurately machine many types of glass without generating micro-cracks, introducing stress, or causing other damage. This study uses LIDE to produce carrier substrates out of glass for integrated optical systems. Due to its transmission characteristics and refractive index, it also functions as optical cladding for integrated polymer optical waveguides. U-shaped cavities are etched into the glass and filled using the doctor-blade technologie with conventional liquid optical polymers, which are then globally cured. This novel manufacturing method is called LDB (LIDE-Doctor-blade). Optical waveguiding in the visible to near-infrared wavelength range is possible by the higher refractive index of the cured polymer. The waveguide is embedded in a near-surface cavity, with no additional upper cladding other than air to the environment, created by a combination of subtractive and additive manufacturing processes. The exposed area can affect transmission quality, and this study purposely exploits this by applying fluids with different properties, such as refractive index and viscosity. Changes in intensity are analyzed and evaluated to demonstrate a sensory function.