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Making Highly Oriented Electrooptical Films of the m/Nitro Aniline Type

IP.com Disclosure Number: IPCOM000086575D
Original Publication Date: 1976-Sep-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 45K

Publishing Venue

IBM

Related People

Shafer, MW: AUTHOR [+3]

Abstract

Meta-nitroaniline and related compounds have been shown to have high electrooptical coefficients and high transparencies [1,2]. Since they are not ferroelectric, and are organic, single crystals thereof are normally strain free and are of good optical quality. This is not true of oxygen octahedra ferroelectric crystals, such as LiNbO(3), in which the electrooptic coefficients are larger but have poorer optical quality due to strains. Good single crystals of m-Nitroaniline have been grown, but it is difficult because of their high vapor pressure. Further, slicing and polishing are additional steps which must be carried out before bulk crystals can be used in any electrooptical devices.

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Making Highly Oriented Electrooptical Films of the m/Nitro Aniline Type

Meta-nitroaniline and related compounds have been shown to have high electrooptical coefficients and high transparencies [1,2]. Since they are not ferroelectric, and are organic, single crystals thereof are normally strain free and are of good optical quality. This is not true of oxygen octahedra ferroelectric crystals, such as LiNbO(3), in which the electrooptic coefficients are larger but have poorer optical quality due to strains. Good single crystals of m-Nitroaniline have been grown, but it is difficult because of their high vapor pressure. Further, slicing and polishing are additional steps which must be carried out before bulk crystals can be used in any electrooptical devices.

In the proposed method for making optical quality films of m-nitroaniline and related compounds, the problems associated with the growth and processing of bulk single crystals are eliminated. The method consists of growing single crystal films on a grooved substrate or on an array of capillaries. It has been previously shown that the fast growth direction of m-nitroaniline is the [001] and that single crystals up to 200 mm can be grown in small glass capillaries either by gravity feed from the top or by capillary attraction from the molten material [3]. The present method will make use of this tendency to grow preferentially in capillaries, by growing the film on a grooved substrate (Fig. 1). This can be done from solution or by gradient cooling of the substrate while it is in contact with the molten material. Since the fast growth direction is the [001], the crystal will orient with this direction parallel to the substrate. The largest electrooptic coefficient for m-nitroaniline is r(33), which means that an electric field applied in the z direction will have the largest effect on the refractive index, n, in the z direction (although it affects the other indices, n(x) and n(y), as well). However, the proposed film configuration can be used in several device configurations in which the film forms the most important part. For example, the film configuration depicted in Fig. 2 requires a voltage V of approx 500 v to rotate the polarization of 5000 Angstroms light propagating in the x direction by 90 degrees.

The grooves can be put into a substrate by various techniques, such as etching using conventional lithography or precision machining techniques such as those used to make diffraction gratings. Highly regular grooves can also be obtained by etching oriented silicon wafers.

Another scheme for making highly oriented "films" is to use...