Surface Plasmon and Waveguide Enhanced Graphene Modulation for On-chip Biosensing in Mid-Infrared Region

Opportunity

Optical light, especially from near-IR to mid-IR spectra, has been instrumental for biochemical analysis and biosensing. Silicon-based CMOS integration for data collection, analysis and on-chip communication has led to the development of various products, such as lab-on-chip devices for remote biological and chemical sample analysis. The use and integration of graphene materials offers dual advantages: 

• Graphene, unlike metals, is compatible with silicon-based CMOS at the front-end processing layers, enabling seamless process integration and cost-effectiveness. 
• Graphene, being a 2D material, enables plasmonic signal enhancement, which can also support broadband modulation. 

This graphene waveguide-based modulator structure has a major advantage over micro-ring resonator structures for on-chip biochemical sensing.

Technology

• The modulator comprises a waveguide having with a silicon core and silicon dioxide cladding. 
• Additionally, the modulator includes a first graphene layer, acting as absorption layer, arranged on the waveguide, and a second graphene layer, acting as gating layer, arranged above the first graphene layer. 
• This configuration enables modulation across a wavelength range that encompasses frequency regimes in the mid-IR spectrum.

Figure 1: Waveguide-enhanced graphene modulation for on-chip biosensing.