Polarization analysis of an asymmetrically etched rib waveguide coupler for sensing applications

Malathi Sathish,Srinivas Talabattula

doi:10.1007/s13320-013-0079-6

Malathi Sathish, Srinivas Talabattula

Open Access

https://doi.org/10.1007/s13320-013-0079-6

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Journal: Photonic Sensors	Publication Date: Jan 30, 2013
Citations: 13	License type: CC BY 2.0

Affiliation: Indian Institute of Soil Science

Abstract

Deeply etched rib waveguides on silicon on insulator platform were not addressed well in research publications. We have analyzed single mode condition and polarization independence of a deeply etched rib waveguide (DE-RW) structure from biosensing perspective. With this rib structure, an asymmetrically etched integrated optic directional coupler has been numerically modeled to have the same coupling length for quasi- TE and TM modes. The coupling coefficients with the glucose solution as an upper cladding were calculated using a full vector mode solver, and the bulk refractive index sensitivity of the sensor was found as 28.305×10 -2 /RIU for a fundamental quasi-TE mode.

Highlights

Directional couplers (DCs) are formed by placing two integrated optic waveguides in close proximity
This work apprehended the significance of three domains, viz., (1) single mode condition of deeply etched rib waveguide (DE-RW) with the bio clad, (2) the asymmetrically etched rib waveguide coupler, and (3) condition for polarization independence
We simulated a bulk sensing environment with the glucose solution as the upper clad on the optimized device

Summary

Introduction

Directional couplers (DCs) are formed by placing two integrated optic waveguides in close proximity. Researchers worked on couplers fabricated with lithium niobate, GaAs, InP or SiO2 [1] waveguides which normally had a larger cross section Those structures demanded a wide gap between waveguides and pushed the coupling length limit to the millimeter and centimeter range. Pogossian et al [4] compared experimental results with the effective index method (EIM) and proposed a similar equation They claimed that the value of α in (1a) was zero instead of 0.3 as a condition for single mode propagation. We have analyzed the directional coupler formed with the least explored deeply and asymmetrically etched rib waveguide configuration and their application as a bio sensor. This work apprehended the significance of three domains, viz., (1) single mode condition of DE-RW with the bio clad, (2) the asymmetrically etched rib waveguide coupler, and (3) condition for polarization independence.

Waveguide design

Directional coupler design and simulation

Glucose sensing

Conclusions