Emeritus Professor and B. Seymour Rabinovitch Endowed Chair in Chemistry Emeritus
George B. Kauffman Professor of Electrical Engineering
Executive Director, NSF STC on Materials & Devices for Information Technology Research
Director, DoD MURI Center on Polymeric Smart Skin Materials
Director, NSF NIRT on Optoelectronic Materials
Director, DARPA/UW MORPH Program
Ph.D. Harvard University, 1971
(Physical, Organic, and Materials Chemistry)
Over the last two decades, advances in electronics have revolutionized the speed with which we perform computing and communications of all kinds. Three key technologies combined to create a platform that enabled the electronic revolution: semiconductor materials, automated microfabrication of integrated electronic circuits, and integrated electronic circuit design. As a result, the mass manufacturing of low-cost integrated circuits has become possible. But now we are outgrowing the performance of electronics in many applications. Signal propagation and switching speeds in the electronic domain are inherently limited. One area where these limitations are seen clearly is in telecommunications, where bandwidth expansion is desperately needed. To overcome these barriers, we must enter a new computing and communications revolution-this time based on photonics. Photonics plays some crucial and complementing roles to electronics in many application domains. Examples of successful use of photonics can be found in broadband communications, high-capacity information storage, and large screen and portable information display. As demands for information bandwidth increase, information photonics is becoming more and more important in every aspect of today’s technology-driven society. The success of a new technology, however, largely depends on the progress achieved in finding and fabricating new high- performance and cost-effective materials. Recently, as the knowledge base of polymeric materials widened, new functions for polymers have been actively investigated. New and improved polymeric materials were found to show promises in generating, processing, transmitting, detecting, and storing light signals.
Nonlinear optical (NLO) materials, especially organic and polymeric ones, have continued to be at the forefront of research activities since the mid-1980s. High NLO susceptibility, fast response time, low dielectric constants, small dispersion in the index of refraction from dc to optical frequencies, virtually endless possibilities of structural modification, and ease in processability are some of the properties of conjugated organic systems uniquely suited for their applications in photonic devices, such as the frequency converters, high-speed electro-optic (E-O) modulators and switches. In particular, a low half-wave voltage (Vp) of 0.8 V has been achieved recently in a polymer waveguide modulator using highly nonlinear organic chromophores and push-pull poling and driving techniques. This discovery, together with a recent demonstration of exceptional bandwidths (as high as 150 GHz) and ease of integration with very large scale integration (VLSI) semiconductor circuitry and ultra-low-loss passive optical circuitry, have provided a solid foundation for using polymeric materials in next-generation telecommunications and information processing.
It is well known that the second-order NLO properties originate from non-centrosymmetric alignment of NLO chromophores, either doped as a guest or covalently bonded as side-chains in poled polymers. To obtain device-quality materials, three stringent issues must be addressed:
1. Design and synthesis of high mb (m: the chromophore dipole moment, b: the molecular first hyperpolarizability) chromophores and realization of large macroscopic E-O activity in the chromophore-incorporated polymers;
2. Maintenance of long-term temporal stability in the E-O response of the poled materials in addition to their high intrinsic stability toward the environment such as heat, light, oxygen, moisture and chemical;
3. Minimization of optical loss from design and processing of materials to fabrication and integration of devices.
NSF Science and Technology Center on Materials and Devices for Information Technology Research (NSF-CMDITR)
The Research and Development mission of this project is divided into four central thrusts supported by two core facility activities. Experimental R&D activities are supported by an "end-to-end" theoretical thrust that focuses on quantitative prediction of phenomena ranging from the atomic & molecular level to the performance of integrated systems. Quantum mechanics, so successfully used to predict the properties of molecules and clusters of atoms, is being extended to develop accurate intermolecular (interatomic, interionic) potentials necessary to predict crystallization phenomena and the formation of nano- and microscale ordered structures by self-assembly and "applied force" processing protocols. The thrust on electro-optic and all-optical devices focuses on the exploitation of recent advances in the development of materials with very large second and third order optical nonlinearities for a variety of applications. The third thrust focuses on development of new light sources, optical amplifiers, and organic electronics. The fourth thrust deals with the nanofabrication and microfabrication, by new methodologies, of novel optical and electronic circuit and device structures and the exploitation of the self-assembly for the fabrication of nanostructured materials. For example, new two-photon photolithography of 3-D optical circuits will be exploited. Another example is the development of novel photonic bandgap devices and circuitry. These research thrusts are supported by Core Facilities in Materials Synthesis (including Scale-Up facilities) and Device Fabrication.
Realization of New and Enhanced Materials Properties Through Nanostructural Control
Research has focused on the following material areas and research missions: (1) Organic electro-optic materials with the objective of realizing materials characterized by electro-optic coefficients greater than 600 pm/V at telecommunication wavelengths and which pass Telecordia standards. New processing techniques have been developed for fabrication 3-D devices and circuits and for achieving low insertion loss electro-optic devices including active wavelength division multiplexing (WDM) transmitter/receiver systems. The Dalton research group currently serves as the national resource for state-of-the-art electro-optic materials providing materials to government, industry, and academic researchers. (2) Metal core dendrimer materials have been developed for applications as sensors, organic light emitting diodes, and light harvesting solar cell coatings. Materials have also been designed for improved emission properties and photochemical stability both by systematic design of the chelated metal and by design of the surrounding dendrimer structure.
L. R. Dalton, P. A. Sullivan, and D. H. Bale, “Electric Field Poled Organic Electro-Optic Materials: State of the Art and Future Prospects,” Chemical Reviews, 110, 25-55 (2010).
J. G. Grote, L. R. Dalton, P. Sullivan, B. H. Robinson, B. Eichinger, A. K.-Y. Jen, S. Benight, I. Losilkin, and D. H. Bale, “Definition of Critical Structure/Function Relationships and Integration Issues for Organic Electro-Optic Materials,” Nonlinear Optics and Quantum Optics, in Press (2010).
P. A. Sullivan and L. R. Dalton, “Theory-Inspired Development of Organic Electro-Optic Materials,” Accounts of Chemical Research, 43, 10-18 (2009).
L. R. Dalton, D. Lao, B. C. Olbricht, S. Benight, D. H. Bale, J. A. Davies, T. Ewy, S. R. Hammond, and P. A. Sullivan, “Theory-Inspired Development of New Nonlinear Optical Materials and Their Integration into Silicon Photonic Circuits and Devices,” Opt. Mater., published on-line, doi:10.1016/j.optmat.2009.02.002 (2009).
P. A. Sullivan, H. L. Rommel, Y. Takimoto, S. R. Hammond, D. H. Bale, B. C. Olbricht, Y. Liao, J. Rehr, B. E. Eichinger, A. K.-Y. Jen, P. J. Reid, L. R. Dalton, and B. H. Robinson, “Modeling the Optical Behavior of Complex Organic Media: From Molecules to Materials,” J. Phys. Chem. B, 113 (47), 15581-15588 (2009).
S. J. Benight, D. H. Bale, B. C. Olbricht, and L. R. Dalton, “Organic Electro-Optics: Understanding Material Structure/Function Relationships and Device Fabrication Issues,” J. Mater. Chem., 19, 7466-7475 (2009).
Fellow (Inaugural Class), American Chemical Society (2009)
Lifetime Achievement Award of the SPIE-International Society of Optics and Photonics (2008)
Fellow, SPIE-International Society of Optics and Photonics (2008)
Dalton Festschrift Issue of the Journal of Physical Chemistry (2008)
B. Seymour Rabinovitch Chair Professor of Chemistry, University of Washington (2008)
University of Utah Frontiers of Science Lectures & Davern/Gardner Laureateship (2007)
IEEE/LEOS William Streifer Scientific Achievement Award (2006)
Fellow, American Association for the Advancement of Science (2006)
Senior Member, IEEE (2006)
QEM (Quality Education for Minorities)/MSE (Mathematics, Science, and Engineering) Network 2005 Giants in Science Award
Dow/Karabatsos Lecture Series and the Alumni Distinguished Lectureship, Michigan State University (2005)