Photonic crystals (PCs) are attractive optical materials for controlling and manipulating the flow of light, as they are composed of periodic dielectric or metallic-dielectric nanostructures and affect the propagation of electromagnetic waves. When a structural defect is introduced in the PCs, a photon-localized state can be created in the photonic band gap and the electrical field around the defect can be confined and enhanced. Control of defect modes by PC structures has been becoming a key technology for many new photonic devices, like photonic crystal fibers, photonic chips, low-threshold lasers, and optical biosensors.
Researchers at the University of Michigan have developed a novel PC-metallic structure, where the structures are in a total-internal-reflection (TIR) geometry. This unique configuration introduces a new plasmon excitation mechanism, whereby the excited plasmon modes satisfy the conditions for both resonance and plasmon modes in the PC and the metallic structure, respectively. Moreover, the incident light from a specific wavelength can be engineered to excite the plasmon modes, as well as be greatly absorbed, reflected or enhanced by the PC-Metallic structure. To date, this structure has been applied for the development of novel broad-band, all-optical ultrasound transducers for high resolution ultrasound imaging, highly-sensitive biomolecular sensor, enhanced total-internal-reflection fluorescence (TIRF) microscopy, and surface-enhanced- Raman spectroscopy (SERS), but the structure may be useful for various integrated systems, such as optical fibers/ waveguides and combination of biosensing and TIRF or SERS, to provide more detailed information for biomolecular interactions.
Applications and Advantages
- All-optical ultrasound transducers (transmitter or/and receiver)
- Enhanced fluorescence microscopy and Raman spectroscopy
- Integrated systems which combine the above Advantages
- Simple configuration, for easy fabrication and low manufacturing cost.
- Provides a narrow and deep resonance dip, resulting in higher sensitivity.
- Large intensity enhancement, offering a powerful and unique substrate for intensity-related measurements.