Several extraordinary recent achievements place the field of microresonators at the frontier of modern photonics. In the Dec. 10 issue of Optics Express, papers explore advanced silicon modulators in the nanoscale, "photonic nanojets" for biomedical applications and the longest photon lifetime in a photonic crystal nanocavity observed to date. According to Dr. Vasily Astratov from the University of North Carolina at Charlotte, editor of this issue, research on microresonators results in "new physics" and leaves a world of new science to explore.
With recent scientific advances (specifically, the ability to create microresonators with quality (Q) factors in excess of 100 million in chip-scale structures), microresonator research has entered a new era where fundamentally new physical properties and abundant applications are within reach. In communications, as the industry moves toward integrating devices on a single chip, research into microresonators centers on the need for very fine frequency selectivity (and tunability) and smaller and smaller resonators. Other efforts are exploring focusing light in spherical and cylindrical cavities, resulting in a new concept dubbed “photonic nanojets” that enables biomedical, atmospheric and ocean optics applications. Yet further research explores how microresonators with high Q factors, in combination with small modal volumes, can be achieved and lead to additional applications – from single molecule detection in biochemical sensing to developing slow light structures.
The following papers are some of the highlights of the Optics Express focus issue on microresonators. All are included in volume 15, issue 25, and can be accessed online at www.OpticsExpress.org.
- A paper from IBM highlights a microring modulator with a 25-fold improvement in sensitivity that may be driven directly by digital CMOS electrical signals with less than 1V amplitude. "Optical modulation using anti-crossing between paired amplitude and phase resonators," William M. J. Green, Michael J. Rooks, Lidija Sekaric, and Yurii A. Vlasov, IBM's T.J. Watson Research Center. pp. 17264-17272.
- New research from Kyoto University reports the observation of the longest photon lifetime of 2.1 ns in a photonic crystal nanocavity, corresponding to 400,000 optical cycles. "High-Q nanocavity with a 2-ns photon lifetime." Takahashi, H. Hagino, Y. Tanaka, T. Asano, and S. Noda, Kyoto University. pp. 17206-17213.
- A new paper from Northwestern and the University of New Mexico explores new ideas about achieving super resolution using photonic nanojets, potentially for the detection of bio and nanoparticles in applications including cancer detection. "Subdiffraction optical resolution of a gold nanosphere located within the nanojet of a Mie-resonant dielectric microsphere." A. Heifetz, J.J. Simpson, S.-C. Kong, A. Taflove and V. Backman, Northwestern University and the University of New Mexico. pp. 17334-17342.