Session CB - Optics; Optical Materials.
INVITED session, Saturday morning, May 03
Room 217, OLSCAMP

[CB.01] Fabrication and Testing of a Photorefractive Polymer Film

We report on fabrication and testing of photorefractive polymer composite film DMNPAA/PVK/ECZ/TNF(B. Kippelen, Sandalphon, N. Peyghambarian, S. R. Lyon, A. B. Padias and K. Hall Jr., ``New highly efficient photorefractive polymer composite for optical-storage and image-processing applications,'' Electron. Lett.), 29, 1873-4 (1993). The fabrication method including the synthesis of the non-linear chromophore (DMNPAA) is described. The performance of the material is evaluated. Dependence of the diffraction efficiency on the geometry of the polymer film and writing beams is investigated in a DFWM experiment at 633nm wavelength of the HeNe laser. The TWM gain for p- and s-polarized light and different magnitude of the external field, its index modulation, and sensitivity data will also be presented.

[CB.02] Periodically Poled Frequency Conversion in Barium Titanate

This abstract was not submitted electronically.

[CB.03] SiC Micropipe Sprecta

This report focuses on the spectral response of 4H SiC PN junction micropipes when reverse and forward biased. Reverse biased 4H SiC PN junctions give a very strong UV line, 385nm (3.22eV), and blue line, 475nm (2.61eV). In the forward bias direction the spectra do not contain the UV, only the blue line, 490nm (2.53eV), with considerably better resolution. For isolating and measuring the micropipe spectra and structure, a sample fixture was fabricated from a power transistor case. In order to activate the micropipes in the SEM, a vacuum feed-thru was made from another power transistor case. The emitter and base leads were used as the vacuum feed-thru and were used to mount a very fine spring for making contact to the 1mm X 1mm PN junction on the SiC chip. In our attempts to study these pipes and their properties, we utilized the SE, BSE, and X-ray detectors on the SEM, a stereo microscope, and a grading monochrometer. From the utilization of this equipment, we found the locations of the micropipes, the forward and reverse bias spectrum, and the possible structural faults in the SiC. Thanks to Dr. Philip Neudeck at LeRC, and Dr. Kenneth Bladh of Wittenberg.

[CB.04] Calculations of the Structure,Dipole Moment and Hyperpolarizability of DCM and Sulfur Substituted DCM (DCMS) and Comparison with Measured Electro-optic Properties

Recently, electro-optical properties of DCM in DCM-polyimide guest/host system have been investigated (S. Ermer et al, Appl. Phys. Lett.,61(19)2272(1992)) by Ermer et.al. They reported an EO coefficient r33 of 3.4 pm/V and a half-wave voltage of 24V for a poled triple-stack structure. In our effort to verify the structure-properties relationship for these materials, it was of interest to investigate the structures of DCM and DCMS and to calculate their electron densities, dipole moments and hyperpolarizabilities, as the crystal structure of DCM is not yet available. Using the AM1 Hamiltonian we have performed MO calculations with the following results: DCM: \mu = 9.38D, \alpha = 7.598, \beta = 43.97, \gamma = 252.86; DCMS: \mu = 8.99D, \alpha =8.121, \beta = 44.09, \gamma = 240.83. (alpha,beta,gamma in conventional esu units.) It is well established that dicyano groups are very good acceptors (S.P. Sinha, Bull. Amer. Phys. Soc., 40(14),2109(1995)) and dimethylamino groups are good donors. These values compare well with earlier calculations on DCM and other structurally similar chromophores (C.R. Moylan et al, Proc. SPIE, 2285,17-30 (1995)). We have also measured r33 = 2 pm/V for a single layer DCM system. Salient features of the calculations and experimental results will be discussed.

[CB.05] Structure, Electron Densities, Dipole Moment and Hy\-per\-po\-la\-ri\-za\-bi\-li\-ties of trans-1-\-Car\-ba\-zo\-li\-um-\-3,4,4-\-tri\-cyano\-buta\-diene (TCBC) and Comparison with the Unsubstituted Chromophores, cis and trans-1-Amino-3,4,4-tricyanobutadienes

Recently, two-photon photoluminescence from organic chromophores containing tricyanobutadiene groups has been reported. To correlate the structures-properties relationship, we have theoretically investigated the structure and hyperpolarizabilities of TCBC and compared the properties with the unsubstituted tricianobutadienes, e.g. \itcis- \rmand \ittrans-[H_2N-CH=CH-C(CN)=C(CN)_3] (ATCB), as the crystal structure of TCBC is not yet available. Using AM1 Hamiltonian, we have performed MO calculations with the following results; TCBC: IP(eV)=8.739, \mu(D)=6.115, \alpha=7.133, \beta=38.39, \gamma=123.65esu; \itcis-ATCB: IP(eV)=9.046,\mu(D)=6.898, \alpha=3.006, \beta=8.751, \gamma=7.814esu; \ittrans-ATCB: IP(eV)=9.012, \mu(D)=7.558, \alpha=3.106, \beta=12.272, \gamma=9.890esu. The amino and substituted amino groups are strong donors while the cyano groups are strong acceptors. These values compare well with other structurally similar and related chromophores. We discuss salient features of calculated structures and electron distributions on the chromophores.

[CB.06] Optical Properties of Ge-Se-Te Glassy Films

This abstract was not submitted electronically.

[CB.07] Effects of Indium Doping on GaSe Crystal Quality and Second Harmonic Generation

This abstract was not submitted electronically.

[CB.08] Multichannel Optical Splitter without Bends

We present the theory of a "bend-free" multistage waveguide splitter designed to direct a single optical signal into N rectangular channels carrying given fractions of the input power. The use of planar geometry waveguides, and the absence of bends, greatly simplifies the fabrication of the separate channels of the splitter. Our treatment makes use of a supermode formalism for the description of the field amplitudes in the channels of the splitter, combined with the "resonance method" for determination of the propagation constants and profile functions of the supermodes. The supermode formalism provides an advantage relative to the coupled mode theory in that it guarantees a conservation of power. Our analysis takes into account both transverse dimensions of the rectangular channels of the waveguides. We make use of the theory to design the layout of a new practical device and to analyze its operation.

[CB.09] UV/VIS/NIR Optical Absorption of a Si-implanted Layer in Quartz

A Lambda-9 UV/VIS/NIR double beam, double monochromator spectrophotometer was used to record transmission and reflection of Si-implanted quartz referenced to unimplanted quartz. The quartz was implanted to 8x10^17/cm^2 at 150 keV. Transmission and reflection data were obtained for both as-implanted samples and samples annealed for 1 hour at 1200^oC in flowing Ar. The spectral range covered 250nm - 800nm (4.96eV - 1.55 eV). This information was used to calculate the absorption coefficient for the implanted Si layer. The absorption spectra will be presented and discussed.

[CB.10] Interface Effects and the Discrepancy in Zeeman Splitting of the Main Transition in Small-Offset Superlattices

This abstract was not submitted electronically.

Part C of program listing