Dissertation Defense

Optofluidic Lasers and Their Bio-sensing Applications

Wonsuk Lee

Novel optofluidic ring resonator (OFRR) lasers resolving problems of existing schemes are suggested and DNA melting analysis with the laser is demonstrated. A PDMS-based OFRR laser using two optically coupled ring resonators in different sizes has addressed an intrinsic multi-mode emission of ring resonator laser. The single-wavelength lasing by Vernier effect can be tuned by modification of refractive index of the gain medium as well. A micro-bubble filled with liquid gain medium mimics the droplets in air that have 3-dimensional optical confinement. The quasi-droplet laser based on the micro-bubble shows superior lasing characteristics due to its sub-micron thin wall and enables repetitive interrogation and easy directional laser emission out-coupling without evaporation or size/shape variations. Microdroplets are delivered to the capillary OFRR downstream and laser emission, which can conveniently be coupled into an optical fiber, is achieved. An efficient FRET lasing is also demonstrated making the microdroplet an attractive reaction chamber with small sample volume. Furthermore, an intracavity DNA melting analysis dramatically improves discrimination of optical signals. The laser amplifies thermodynamic difference in between the target DNA and the base-mismatched DNA. The optofluidic laser based DNA analysis leads to novel optoÏ uidic devices that enable rapid and simple detection of DNA sequences.

Sponsored by

Xudong (Sherman) Fan & L. Jay Guo