High sensitive photonic crystal multiplexed biosensor array using sandwiched H0 cavities

Integrated optical sensors based photonic crystal (PhC) structures have emerged as a field of great interest due to their promising characteristics in terms of cost, compactness, flexibility in structural design and easy... [ view full abstract ]

Integrated optical sensors based photonic crystal (PhC) structures have emerged as a field of great interest due to their promising characteristics in terms of cost, compactness, flexibility in structural design and easy extension to the sensor arrays. In addition to these characteristics, they provide a large light-matter interaction due to their photonic band-gap effect. This phenomenon makes the sensors highly sensitive to small refractive index (RI) variations. However, most of studied and experimentally realized PhC sensors operate as a single or a point sensor. Therefore, to overcome the single purpose performance of the sensor and to make the detection of different analyte simultaneously on a single platform possible, photonic crystal sensor array is a better choice. In this context, we demonstrate a high sensitive photonic crystal integrated biosensor array, considering the multiple sensing performance and label-free Biomolecular detection. In order to further improve the detection level and simultaneously restrain the crosstalk value between the adjacent biosensors, the well-known technique of wavelength division multiplexing to spatially separate the integrated biosensor has been used. The device platform consists of an array of three sandwiched H-1 cavities patterned above silicon on insulator (SOI) substrate (Figure 1). Each cavity has been designed for different resonance wavelength and different cavity spacing. Results obtained by performing finite-difference time-domain (FDTD) simulations, indicate that the response of each sensor unit to the RI variation is completely independent and the resonance spacing between the adjacent sensors is wide enough to ensure high multiplexed detection. Considering water absorption at telecom wavelength range, a RI sensitivity of 530nm/RIU and a quality factor over 104 are both achieved with an average accompanied crosstalk of -26.12 dB. These features make the designed device a promising element for performing label-free multiplexed detection in monolithic substrate for medical diagnostics and environmental monitoring.

Figure.1. 3D schematic diagram of the integrated PhC biosensor array based on H-1 sandwiched microcavities. The blue holes refer to the sensing filled initially filled with water