On-Chip Integration of Photodetector and Sensor: A Multimodal Photonic Device for Sensing Applications

Abstract

In this paper, we present the design and development of a novel miniaturized multimodal photonic sensor, which can be configured dually as a photodetector in the absorptive mode and as a pyro-detector in the photonic sensor mode. In this paper, we have fabricated a polyvinyl alcohol (PVA) photoactive layer-based MEMS structure and analysed the effect of effective inter-electrode separation on the photoactive area of the photoactive film using the four quadrant metal-semiconductor polymer-metal (MSM) design on the photoresponsivity of this device in terms of photoconductive and the pyroelectric responses. Our analysis reveals that the interdigitated electrode configuration is best suited for photoconductive response while the cross-electrode configuration with large effective inter-electrode spacing is advantageous for pyroelectric measurement in the infrared region. Here, the unique design of this device offers the choice of electrode configurations that enables the utility of this device in various regions of the electromagnetic spectrum. In this regard, we demonstrate the optical detection of localized surface plasmon resonance of immobilized gold nanoparticle monolayer in the visible region, employing the absorptive mode and the detection of the spectroscopic signature of RDX and TNT molecules ( $134~\mu \text{g}$ /cm $^{2})$ in the midinfrared region using photonic sensor mode. This paper paves a way for designing a low-cost PVA-based miniaturized sensor architectures with huge potential for on-chip real-time detections in various fields of scientific and commercial applications.