Increasing the angular sensitivity of two-dimensional photonic crystal based sensors to arbitrary values

Area of Science:

• Photonics
• Optical Sensing
• Materials Science

Background:

• Guided Mode Resonance (GMR) in photonic crystals (PhCs) offers potential for sensitive optical sensing.
• Existing PhC designs often face limitations in achieving ultra-high angular sensitivity.

Purpose of the Study:

• To introduce a new PhC design for optical sensing utilizing GMR.
• To theoretically and experimentally demonstrate enhanced angular sensitivity in PhCs.
• To validate the relationship between group velocity and angular sensitivity.

Main Methods:

• Theoretical modeling of PhC behavior for optical sensing.
• Fabrication of PhCs using polycrystalline diamond on insulator.
• Experimental measurement of GMR modes and angular sensitivity.
• Validation of theoretical predictions against experimental data.

Main Results:

• Demonstrated inverse proportionality between angular sensitivity and group velocity.
• Achieved ultra-low group velocity (c/80) at 800 nm wavelength.
• Inferred an angular sensitivity of approximately 500° per refractive index unit.
• Experimental validation of the designed PhC's high sensitivity.

Conclusions:

• The proposed PhC design enables significantly enhanced angular sensitivity for optical sensing applications.
• Controlling group velocity is a key strategy for optimizing PhC sensor performance.
• The fabricated diamond-based PhCs show promise for next-generation refractive index sensors.