Events Calendar

Refractive Index Engineering by Fast Ion Implantations: A Generic Method for Constructing Multi-components Electrooptical Circuits

Speaker: Aharon J. Agranat, The Hebrew University of Jerusalem

Talk Title: Refractive Index Engineering by Fast Ion Implantations: A Generic Method for Constructing Multi-components Electrooptical Circuits

Abstract: Refractive index engineering (RIEng) by ion implantations in electrooptical substrates is a generic methodology for constructing multi-component integrated circuits of electrooptic and nanophotonic devices with sub-wavelength features operating in the visible - near IR wavelengths. RIEng exploits the fact that ions that are incident at high energies on a substrate of oxygen Perovskites form within the depth of the substrate a well confined layer of Frenkel defects which cause the layer to be partially amorphized. The refractive index in this layer differs significantly from that of the crystalline substrate. It was also found that the waveguiding structures are thermally stable after being subjected to an annealing process, and exhibit a propagation loss of 0.1 dB/cm.



The essence of the method is to perform spatially selective implantations for sculpting complex 3D pre-designed patterns with reduced refractive index within the volume of the substrate. Sculpting 3D structures is enabled by combining three techniques that form a complete toolbox for constructing the circuits: (i) Lateral patterning: defining the lateral distribution of the amorphization by performing the implantation through a “stopping mask” which causes the amorphized region to replicate the contour of the topography of the mask; (ii) Longitudinal patterning: determining the depth of the amorphized region by controlling the energy of the implanted ions; and (iii) Selective etching: selective etching of the amorphized material that were created by the implantation process. In addition to these, the 3D structures can be made to be electrically conductive and photoconductive by using high fluence of protons as the implanted species. RI Eng was also combined with laser ablation to form structures with high contrast of the difference in the refractive index between the core and the cladding.



A number of devices that were constructed in a substrate of potassium lithium tantalate niobate will be described, including an optical wire, a channel waveguide array, a protons grating, and a waveguide constructed by a combination of laser ablation and implantation of alpha particles.

Biography: Professor Ronny Agranat is the director of the Brojde center for innovative engineering and computer science, and the incumbent of the Nahman Jaller chair of Applied Science at the Hebrew University of Jerusalem. Agranat holds a B.Sc degree in physics and mathematics (1977), an M.Sc degree in Applied Physics (1980), and a PhD degree in physics (1986) all from the Hebrew University of Jerusalem. His Ph.D thesis was on the subject of the dielectric mechanism of the photorefractive effect which he discovered. From 1986 to 1997 he was a senior research fellow and a visiting senior research associate at the California Institute of Technology (Caltech), where he worked on the development of microelectronic artificial neural networks based on charge transfer devices which he invented, and the growth and investigation of paraelectric photorefractive crystals. In 1991 he joined the faculty of the Hebrew University of Jerusalem and founded the optoelectronic computing laboratory. The laboratory mission is to conceive and develop optoelectronic devices and systems that will expand the capabilities of the computing and communication technologies that are the physical basis of the cyberspace. One of the main themes pursued by Agranat is to exploit the special features of the quadratic electrooptic effect at the paraelectric phase for the purpose of constructing various optoelectronic device, in particular for wavelength selective switching applications. To that end Agranat invented and developed a new electrooptic crystal: potassium lithium tantalate niobate (KLTN). Agranat is the inventor of Electroholography which is a generic optical switching method based on governing the reconstruction process of volume holograms by the applications of electric fields. Electroholography was invented for the purpose of interconnecting electronic processors by holographic devices. In particular it has been identified as the leading concept for dynamic wavelength selective routing in WDM optical fiber communication networks. For the invention of Electroholography and the KLTN crystal Agranat was awarded the Discover Innovation Award (awarded by the Discover magazine and the Christopher Columbus Society) for the leading invention in the area of communication for the year 2001. Agranat is a member of the Hebrew University Interdisciplinary Center of Neuro-Computing, and a fellow of the Optical Society of America. Agranat was also a cofounder and director of Trellis–Photonics that was founded for exploiting Electroholography in telecommunication applications. Agranat is the author of many scientific papers, and holds 24 patents in the areas of microelectronics, optoelectronics and materials science.

Host: Alan Willner, x04664, willner@usc.edu

Location: Hughes Aircraft Electrical Engineering Center (EEB) - 539

Audiences: Everyone Is Invited

Contact: Gerrielyn Ramos