Speaker
Description
The emerging customized point of care (POC) and home health care diagnostic applications demand the development of highly integrated, compact, smart and low cost biosensors. The recent advances in the integrated silicon photonics have stimulated research around the globe on the development of such label free chemical and bio-sensing platform using photonic resonant structures. Conventional sensors produce a single signal which responds to different parameters such as refractive index change, molecular binding, temperature gradient, etc., necessitates the requirement of several iterations and intensive post measurement processing to decouple molecular information from the modulated signal, or the requirement of separate sensor elements for each parameter, which makes the system more complex and costly. So it is highly desirable for a biosensor to have multi parametric functionality and we propose a multi parametric sensing schemes based on grated waveguide arrays in silicon - on - insulator (SOI) optical bench platform.
In this approach, the grated waveguide (GWG) will act as sensor as well as detector also. The molecular binding will induce strain on the sensor surface which will modulate the grating period resulting the shift of only the band edge transmission. So in the proposed device the strain effect can be harnessed by suspending the waveguide grating and hence the same device can generate two sensitive signals simultaneously, each carries unique information about the molecular binding reaction providing a means for accurate quantitative and qualitative assessment without the need for multiple iterations and laborious post measurement processing.
We have fabricated suspended Silicon grated waveguide using standard CMOS fabrication techniques. The differential tuning of band edge transmissions in a phase shifted waveguide grating has been demonstrated using a mathematical model based on transfer matrix method and the experimental results show the presence of multiple transmission modes, which can be tuned selectively by altering different parameters such as surrounding refractive index or molecular binding.
Reference:
1. J.D. Joannopolous, S.G. Johnson, J.N. Winn, R.D. Meade, Photonic Crystals, Molding the Flow of Light, second ed., Springer, Berlin, 2007.
2. D. Gerace, M. Agio, L.C. Andreani, P. Lalanne, Cavity modes in one-dimensional photonic crystal slabs, Opt. Quant. Electron. 37 (1–3) (2005) 277–292.