Nanoplasmonic Sensors Based on Chirped Crossed Surface Relief Gratings

Abstract

This work presents a new type of nano-plasmonic sensor based on crossed surface relief gratings (CSRGs) with gradually varying pitch generated on top an azobenzene thin films using a 532 nm laser and a modified Lloyd mirror setup. A cylindrical lens is placed in front of half of the beam’s path, scattering the light horizontally, which results in the varying pitch linear gratings. Crossed gratings are created by writing a varying pitch grating on top of an orthogonally placed constant linear grating; therefore, producing a chirped-pitch cross grating. CSRGs have already created a unique surface plasmon resonance (SPR) sensors, since no light passes through them except a narrow bandwidth where SPR conversion occurs. A large bandwidth of SPR wavelengths are excitable along the chirped grating, making them suitable as a new generation of biosensor that obtains an accurate signal using multiple wavelengths of light upon a biological or biochemical event. Alternatively, the sensor can be divided up to different sections, where each section could be used as a device by itself, with specific photonic characteristics, that can be tailored for multiple, specific, biosensing requirements.