Liquid crystal-based tunable photonic crystals for pulse compression and signal enhancement in multiphoton fluorescence

A unique device to enhance the fluorescence excitation with a maximum signal gain of 15-fold is demonstrated here. A one-dimensional photonic crystal infiltrated with liquid crystal as a central defect layer is designed for the enhancement of multiphoton fluorescence. Based on the linear dispersion properties near the edge of photonic bandgap, compression of femtosecond laser pulses can be realized. In comparison to the typical fluorescence enhancement techniques, this novel method has easy on-chip compression of an excitation pulse, tunable device, bio-friendly design, low damage, and compensation-free characteristics. The photonic bandgap structure employed in this approach has tunable and strong enhancements in fluorescence that enable these devices to find a place in bio-imaging and biophotonic technologies.