Electronic Ceramic Thin Films: Trends in Research and Development
- PDF / 2,339,391 Bytes
- 7 Pages / 604.8 x 806.4 pts Page_size
- 9 Downloads / 272 Views
article since controlled doping on a ppm level and synthesis of high density, highly oriented films are necessary to obtain desired properties such as low optical propagation loss or high photorefractive sensitivity. Single-crystal films of approximately 2 micron thickness are ideal for most integrated optoelectronic applications due to the elimination of light loss from grain boundary scattering. However, for most ferroelectric electro-optic materials, bulk single crystals are difficult to grow, and thus the present status of singlecrystal growth and resultant electro-optic properties are reviewed. Recent efforts to fabricate superconducting thin films as well as the synthesis of dielectric films using solution chemistry techniques will be presented. Further, the use of solution chemistry to control microstructure and semiconductor electrical properties in boundary layer electronic ceramics by controlled doping at the ppm level will be discussed. Electro-optic Materials: An Introduction
The key components for optical communication systems, optical computing systems, optical spectrum analyzers, and fiber sensors are based on electro-optic materials. The electro-optic effect is essentially the change in refractive index of a material UNPOLARIZED LIGHT
with an applied electric field. For the aforementioned applications, high frequency (>1 GHz) electro-optic switching is of particular interest. Lithium niobate is presently the material of choice for external, high speed, optical guided-wave switching applications because it is readily available in single-crystal form with less than 1 db/cm optical loss. Several ferroelectric electro-optic materials would be superior to single-crystal lithium niobate for high speed, electrooptic modulation applications if they could be synthesized as thin films with low optical loss. Materials such as potassium niobate (KN), barium titanate (BT), and strontium b a r i u m n i o b a t e (SBN) h a v e electro-optic coefficients that exceed those of lithium niobate by factors of 10 or more. Because of their high electro-optic coefficients, half-wave retardation can be achieved in 10 times less volume than for lithium niobate. The small size of optoelectronic devices made from these materials is especially conducive to space and military applications. Exploration of vapor deposition and solution chemistry techniques to synthesize thin films of these materials is very attractive for device integration.
9
POLARIZER P
2
Figure 1. Prototype optical shutter with ferroelectric/electro-optic material as the active component.40 The shutter is shown in the full open state at half-wave voltage.
PAGE 40, MRS BULLETIN, OCTOBER 1/NOVEMBER 15, 1987
Figure of Merit for High Speed Electro-optic Materials
A quantitative comparison of high speed transverse electro-optic materials can be made by developing a figure of merit for materials used in a prototype device. Holman9 developed such a criterion for a channel waveguide phase modulator by considering different electrode structures and invoking a
Data Loading...
