Higher Q factor and higher extinction ratio with lower detection limit photonic crystal-parallel-integrated sensor...

Area of Science:

• Photonics
• Nanotechnology
• Optical Sensing

Background:

• Photonic crystals (PhCs) offer unique light manipulation properties.
• Developing integrated nanoscale sensor arrays is crucial for advanced sensing applications.
• Existing methods may face limitations in sensitivity, integration density, or multiplexing capabilities.

Purpose of the Study:

• To introduce a novel 1×4 monolithic PhC parallel-integrated sensor array (PhC-PISA).
• To demonstrate a high-Q factor resonant cavity design for enhanced sensing.
• To evaluate the sensing performance, including sensitivity, crosstalk, and detection limit.

Main Methods:

• Fabrication of a PhC slab with four lattice-shifted resonant cavities.
• Butt-coupling cavities to output waveguide branches for parallel integration.
• Utilizing the finite-difference time-domain (FDTD) method for simulation and analysis.
• Characterizing resonant peak shifts in response to refractive index changes.

Main Results:

• Achieved a high Q factor > 1.5×10⁴.
• Demonstrated independent resonant peak shifts for each of the four sensors.
• Obtained high sensitivities ranging from 51.142 to 62.500 nm/RIU.
• Observed negligible crosstalk and a detection limit as low as 1×10^-4.
• Each sensor exhibited a single peak with an extinction ratio > 25 dB.

Conclusions:

• The proposed PhC-PISA is a viable platform for nanoscale sensing.
• The design enables optical multiplexing sensing with high-density monolithic integration.
• This technology holds significant potential for various sensing applications requiring high performance and integration.