Multi-sensing Platform Design with a Grating-Based Nanostructure on a Coverslip Substrate

Two different thin film designs with a grating pattern are simulated on a soda lime coverslip, which acts as optical waveguide, with the purpose of generating both a lossy mode resonance (LMR) in transmission and reflection bands. This way both phenomena can be made sensitive to different parameters, leading to a multi-sensing device. The first design consists of a grating patterned in a SnO2 thin film deposited on the coverslip. The performance of the device in both transmission and reflection is numerically studied in air for different values of the grating pitch. Small grating pitches (in the order of the µm) are more suitable for generating the reflection bands while larger values (500 µm or more) are required to produce the LMR, when the reflection bands are no longer visible. Due to the inability to obtain both phenomena with this design, a second design is assessed, where the grating is combined with a section of constant thickness. In this case the desired response is obtained, which opens the path to use this device for multi-sensing applications, measuring several parameters at the same time.