NSF CAREER: Photoinduced nanostructures in manganese oxides DMR-0348939

Current demands in the areas of computing and communication require increasing speed of computation and information transfer. This leads to continuing decrease in size of nanofabricated electronic devises, which soon will reach its limit. Alternative solution to this problem is to replace "slow" electronic devices with "fast" photonic ones. Such solution requires the development of optical analogues of electronic integrated circuits capable of routing, controlling and processing optical signals. Scaling down optical and optoelectronic devices to nanometric dimensions and their integration in photonic circuits require novel approaches to light manipulation. One of the promising approaches is based on photonic band-gap materials, which allow control of dispersion and propagation of light. A photonic band-gap may appear in a three-dimensional photonic crystal (a material with periodic modulation of refractive index with a period of the order of the wavelength of light). The necessary condition for the photonic band gap to appear is high (more than 2 to 1) refractive index contrast within a photonic crystal. Application of photonic band-gap structures has already led to remarkable breakthroughs in optical integration. However, creation of a photonic band-gap material is a very difficult technological task.

Unique and novel feature of my experimental program is based on the extreme sensitivity of the manganite materials to external fields, such as magnetic field, temperature, optical illumination, etc. A number of such materials exhibit unique photosensitivity properties. As a result, nanostructuring of these materials may be performed using well-known optical holography techniques. I propose to overcome the problem of inherently weak refractive index contrast of holograms by using extreme sensitivity of the properties of manganites to external magnetic field and temperature. This sensitivity will be used to "develop" the holograms: application of the external fields will result in substantial enhancement of the weak initial refractive index contrast of the holograms, resulting in the potential appearance of photonic band gaps. On the other hand, such photoinduced photonic crystal structures may be easily annealed using, for example, intense light of a CO2 laser, so that new structures can be written in the same region of the sample instead of the old ones. Thus, unique writable and erasable photonic crystal materials may potentially be created. Such materials would be invaluable in numerous photonic device applications.

My research will advance broad areas of materials science and optical technology while simultaneously promote teaching and training via development of novel undergraduate courses at the Towson University, which is primarily an undergraduate institution. Physics majors will have access to the state of the art equipment during their Intermediate Physics Laboratory course and undergraduate research. Research will be brought to the classrooms of non-physics majors in the General Physics course. This research will promote further involvement of women and underrepresented minorities in the novel cutting edge research.