The design of monolithic integration of photonic crystal biosensor to Si-Ge PIN photodetector on silicon photonics platform for compact biosensing system

Abstract

The requirements of compact biosensing system features such as portable, wearable and point-of-care applications require compact design solutions. Optical based biosensor is one of the choices because of the high-sensitivity characteristic. In previous researches, one dimensional photonic crystal 1D PhC optical devices have been demonstrated to work as a biosensor by sensing the refractive index (RI) change of its surrounding. However, for the design of a practical biosensing system, the optical signal needs to be converted to the electrical signal by a photodetector for signal processing. Discreet photonics components result in bulky equipments. Compact biosensing system requires compact design solutions. Monolithic integrated design is a good solution to realize this. Here, the optical biosensor component can be monolithically integrated with the photodetector component. There is still no work which shows the integration of the 1D PhC to a photodetector to get an electrical output which is done in this work. In this work, we show the novel design integration of a monolithic integration of 1D PhC biosensor with a Si-Ge PIN photodetector based on silicon photonics platform. The Lumerical software packages are used to simulate the design. Following silicon photonics design methodology, the design and simulations start at the device level for both of 1D PhC biosensor and Si-Ge PIN photodetector components. The extracted data from the device level simulations are used for the circuit level simulations of the integrated 1D PhC-photodetector for electrical output. The simulation results have shown the integrated 1D-PhC design gave good results, which the output of the circuit in electrical domain shows an acceptable power level and the same shift of peak behavior in sensing as from the previous researches in optical domain. The good result suggest that the design data presented in this work can be used further to design a compact optical based biosensing system.