Resonant dielectric multilayer with controlled absorption for enhanced total internal reflection fluorescence...

Area of Science:

• Optical microscopy
• Nanophotonics
• Biophysics

Background:

• Total internal reflection fluorescence microscopy (TIRF-M) offers high axial resolution for biological imaging.
• Objective-based TIRF-M faces limitations like interference fringes and uneven illumination, degrading image quality.
• Increasing excitation angle to improve illumination uniformity causes significant excitation power loss.

Purpose of the Study:

• To design and optimize 1D photonic crystals for enhancing evanescent fields in TIRF-M.
• To circumvent excitation power loss associated with increased incident angles in TIRF-M.
• To improve image quality by controlling evanescent field intensity at the glass-sample interface.

Main Methods:

• Design of resonant multi-dielectric stacks supporting Bloch surface waves.
• Numerical optimization of photonic crystal structures for TIRF-M angular conditions and fluorescence collection.
• Experimental demonstration of the proposed resonant structure for fluorescence enhancement.

Main Results:

• Development of a dedicated resonant photonic crystal structure for TIRF-M.
• Numerical predictions show adaptation of resonance to angular illumination and collection constraints.
• Experimental validation achieved a 3-fold fluorescence enhancement, aligning with numerical outcomes.

Conclusions:

• 1D photonic crystals can effectively enhance evanescent fields in TIRF-M, overcoming limitations of conventional methods.
• The proposed resonant structures offer a pathway to improved excitation efficiency and image quality in biological imaging.
• This approach provides control over evanescent field intensity and absorption during thin-film deposition.