On-chip biochemical sensor using wide Gaussian beams in silicon waveguide-integrated plasmonic crystal

Area of Science:

• Nanophotonics and Plasmonics
• Biochemical Sensing
• Integrated Optics

Background:

• Surface plasmon resonance (SPR) sensors are crucial for biochemical detection.
• Existing SPR sensors often face limitations in integration and sensing area.
• Nanoscale engineering offers new avenues for enhanced sensor performance.

Purpose of the Study:

• To develop and demonstrate an on-chip biochemical sensor utilizing a waveguide-integrated plasmonic crystal.
• To achieve a large sensing area with low insertion loss for practical applications.
• To evaluate the sensitivity and functionalization capabilities of the proposed sensor design.

Main Methods:

• Fabrication of a two-dimensional nanogap tile (NGT) array integrated with waveguides.
• Utilizing on-chip optical lenses to launch an ultra-wide collimated Gaussian beam.
• Numerical simulations and experimental validation of optical field enhancement and stop-band shift.
• Demonstration of sensor functionalization with monolayer thiol molecules.

Main Results:

• Successful realization of an on-chip waveguide-integrated plasmonic crystal sensor.
• Achieved ultra-wide beam coupling with surface plasmonic crystals and low insertion loss.
• Demonstrated optical field enhancement and stop-band shift for biochemical sensing.
• Obtained a high sensitivity of approximately 260 nm/RIU.
• Confirmed functionalization capability with thiol molecules, analogous to bulk SPR sensors.

Conclusions:

• The developed NGT-based on-chip sensor offers a promising platform for sensitive biochemical detection.
• The sensor design enables a large sensing area and efficient light coupling.
• The demonstrated sensitivity and functionalization potential highlight its applicability in various biochemical sensing scenarios.