We have measured the indices of refraction and dielectric constants along different directions in thin films of the crystalline organic semiconductor compound 3, 4, 9, 10 perylenetetracarboxylic dianhydride (PTCDA). The films were deposited via organic molecular beam deposition, resulting in single-crystalline, ‘‘quasi-epitaxial’’ films. Due to inherent asymmetries in the molecular crystal structure, film ordering results in giant anisotropies in their dielectric properties. For example, the index of refraction measured at a wavelength of λ=1.064 μm in the direction perpendicular to the substrate plane is n⊥ = 1.36 ± 0.01, whereas parallel to the plane, n∥=2.017±0.005, resulting in an index difference of Δn=0.66. Furthermore, the low-frequency dielectric constant of the films is ε⊥ = 1.9 ± 0.1 and ε∥ = 4.5 ± 0.2. To our knowledge, these are the largest anisotropies ever measured for thin films. We discuss a guided wave polarization-selective device which takes advantage of the large dielectric anisotropies characteristic of the thin organic films.

Optical waveguiding in a crystalline organic semiconductor, namely, 3,4,9,10 perylenetetracarboxylic dianhydride (PTCDA), has been demonstrated in slab and rib waveguides using both end-fire and grating coupling at λ 1.064 μm. The effective indices of the transverse electric (TE) modes measured by means of grating coupling are in good agreement with theoretical prediction. A very low propagation loss of 2.5 dB/cm in a PTCDA rib waveguide has been determined from measurements of the scattered light intensity from the top surface of the guide.

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Successful experimentation on acousto-optic Bragg diffraction in a LiNbO3 composite waveguide that consists of an array of parallel but uncoupled channel waveguides directly extended to a single-mode planar waveguide and a titanium-indiffused proton-exchanged (TIPE) microlens array is reported for the first time. A channel-waveguide array, a planar waveguide, a linear TIPE microlens array, a 500-MHz surface acoustic wave transducer, and an integrating lens have all been integrated in a substrate size of 0.2×1.0×2.0 cm to form an integrated acousto-optic Bragg modulator that should find a variety of applications in optical computing, signal processing, and communications. The resulting modulator module has been utilized to perform matrix-vector multiplication.