"Optical frequency combs have become pivotal tools in a wide range of studies, from metrology, gas sensing to astronomy. In 2007 the host laboratory has demonstrated an entirely new approach to generate frequency combs from optical micro-resonators. The physical process responsible for the comb generation is parametric four-wave mixing.The micro-resonator frequency combs not only represent considerably reduction in size, complexity and power consumption, but moreover, the small circumference of optical micro-resonators enable for the first time to generate frequency combs with repetition in the technologically and scientifically interesting range of above tens of gigahertz. The high repetition rates have potentials in applications such as high capacity telecommunications and astronomical spectrometercalibration.The main experimental goal of this proposal is to generate frequency combs in the scientifically and technologically significant ""molecular fingerprint"" mid-infrared spectral region in micro-resonators made of crystalline materials. The crystalline materials feature exceptionally low loss from UV to mid-infrared, and resonators with cavity finesse up to 1 million have been successfully fabricated in the host group. It is envisioned that broadband combs in the mid-IR can be generated in such micro-resonators, and such a mid-IR comb will greatly facilitate molecular spectroscopy, enables multi-heterodyne spectroscopy in the mid-IR and will also have potential in astronomical spectrometer calibration.The applicant is a female scientist who has obtained her undergraduate degree in Taiwan and her PhD at Harvard University (USA) in the group of Quantum Cascade Lasers pioneer Federico Capasso. She started her postdoctoral work in September 2009 at the Max-Planck Institute for Quantum Optics in the host group in the division of Prof. Theodor Haensch. Her experience makes her the ideal candidate to carry out the proposed research project."