Surface plasmon resonance based silicon carbide optical waveguide sensor

• Demonstrate a new SPR waveguide sensor on a wide bandgap semiconductor – SiC.
• The sensor is capable of operating in visible and near-infrared wavelength ranges.
• The confinement factor of the sensor was improved clearly by the SPR effect.
• The sensor performance is promising for chemical and biomedical sensing.

In this paper, we investigated a new surface plasmon resonance (SPR) based optical waveguide sensor formed on a wide bandgap semiconductor material – silicon carbide (SiC). The wide bandgap energy of SiC (Eg=2.2 eV of 3C-SiC polytype) enables the waveguide to operate in the visible and near-infrared wavelength range. Assessment of the potential sensing properties was performed by investigating the confinement factor in fundamental transverse magnetic mode (TM0) using the effective index method (EIM). The results show that at the incident light of 633 nm, a confinement factor of 0.95 can be achieved at the refractive index of n=1.45. Comparing to reported non-SPR structure, the confinement factor of SiC SPR sensor was clearly improved over the refractive index range of n=1.3–1.5, and by more than 3.3 times at n=1.35. The improved sensing property by SPR structure combined with the superior chemical/biological inertness of SiC material and compatibility between SiC and Si device manufacturing makes the proposed SiC SPR sensor very promising for chemical sensing and bio-sensing.