PHOTONICS

Rather than engineering the electronic band structure, as in QCL research, one can modify the photonic band structure of a material by engineering its optical properties (e.g. creating a periodic array of holes within an optical medium). Such structures can be studied on their own or incorporated into QCLs, microfluidic sensors, etc. In addition, studies of the interaction force between optical components due to evanescent coupling of their fields is being carried out.

Postdoctoral fellows: Jiming Bao
Graduate students: Jenny Smythe, Nanfang Yu and Mariano Zimmler

Optical Evanescent Wave Bonding

We are working to observe mechanical deflections in freestanding waveguides that result from evanescent light coming from a nearby waveguide, as well as the evanescent fields of the deflecting waveguide. Our calculations indicate that these waveguide deflections can be attractive (two waveguides bend towards each other) or repulsive (two waveguides bend away from each other) depending on the relative phase of the light in the two waveguides. These attractive and repulsive states are analogous to molecular binding and anti-binding states.

Jenny Smythe in collaboration with Marko Loncar (Harvard), John Joannopoulos, Steve Johnson and Mihai Ibanescu (MIT), and Axel Scherer, Michael Hochberg, and Guangxi Wang (Caltech)

Single Nanowire Optoelectronics

Semiconductor nanowires are promising candidates in the emerging field of nanoelectronics and integrated optoelectronics. Many of their potential applications, however, rely on controllable electrical injection into single nanowires, which still remains a significant technical challenge. In this project, we are working in the development of a novel technique to address this problem. This technique utilizes a planar substrate as a bottom contact and makes possible the precise fabrication of a metallic top contact along the length of the nanowire. Such a technique would make possible the development of new optoelectronic and spintronic devices, such as the first spin-injection nanowire laser.

Jiming Bao and Mariano Zimmler

Erbium Spontaneous Emission Rate Modification in the Vicinity of Metal

The spontaneous emission rate of Erbium atoms is affected by the presence of interfaces with other materials due to the change of the spatial-temporal structure of the electromagnetic modes via boundary conditions. As for the case of an interface with a conducting medium that is located in the near zone of an atom, i.e. at a distance less than the optical transition wavelength, the modification of spontaneous emission rate can be quite dramatic. The phenomenon can be intuitively viewed as the interaction between the real dipole and its image through a quasi-electrostatic near field. Experiment work is performed to confirm the calculation based on the theory.

Jiming Bao and Nanfang Yu