Mark C. Jurich

Temperature dependence of the third‐order nonlinear optical susceptibilities in polysilanes and polygermanes

Optical third‐harmonic generation was used to measure third‐order nonlinear susceptibilities χ(3) for thin films of planar zigzag polysilanes and polygermanes. A χ(3) of 11.3×10−12 esu was measured, the largest value ever reported for a polymer with transparency throughout the visible. The value of χ(3) was found to vary substantially with thermally induced reversible changes in polymer backbone conformation and also with film thickness.

Volume holographic data storage at an areal density of 250 gigapixels/in. 2

One thousand volume holographic data pages, each containing 1x10(6)pixels , are stored in a common volume of LiNbO(3) :Fe by use of the 90 degrees geometry. An effective transverse aperture of 1.6 mm x 1.6mm , realized by repetition of this experiment at each of the eight surrounding locations, results in a demonstrated areal density of 394pixels/mum (2) (254 Gpixels/in. (2)) . Short-focal-length Fourier optics provide a tightly confined object beam at the crystal; the reference beam is angle multiplexed. Data pages retrieved with a 1024 x 1024 CCD camera are processed to remap bad spatial light modulator pixels and to compensate for global and local pixel misregistration and are then decoded with a strong 8-bits-from-12-pixels modulation code. The worst-case raw bit-error rate (BER) before error correction was 1.1x10(-3) , sufficient to deliver a user BER of 10(-12) at an overall code rate of 0.61 user bits per detector pixel. This result corresponds to 1.08% of the well-known theoretical volumetric density limit of 1/lambda(3) .

Absorption and scattering in nonlinear optical polymeric systems

Fundamental absorption measurements were made on organic films which are candidates for nonlinear optical materials applications, in order to gain insight into the loss mechanisms. Photothermal deflection spectroscopy was used to obtain the full absorption spectrum and to explain observed variations in waveguide attenuation. The absorption data provide a complete characterization of the optical spectrum and allow us to select optimal polymer‐chromophore systems. The variations in the attenuation at 832 nm are due to the chromophore absorption, while for wavelengths longer than 1 μm, the C—H vibrational overtones and combination bands of the polymer dominate the spectrum and are likely to be the main source of waveguide attenuation.

Electro-optic effects in two tolane side-chain nonlinear-optical polymers: comparison between measured coefficients and second-harmonic generation

The electro-optic coefficients for the chromophore nitroamino tolane [NAT:HOCH2CH2-N(C2H5)-ϕ-C≡ C-ϕ-NO2] attached to either a poly(methyl methacrylate) or an epoxy polymer have been measured by three different techniques: attenuated total reflection, ellipsometric reflection, and Mach–Zehnder interferometry. All the results for r33 and r13 were consistent and in agreement. A comparison of these experimental methods is given. The ratios between the electro-optic coefficients and the relationships between the coefficients and the second-harmonic components give additional information about these nonlinear-optical polymers. Interestingly, it was found that the observed electro-optic coefficients increased after the samples had aged a few months.

Electro‐optical characterization of poled‐polymer films in transmission

An improved version of the commonly employed C. C. Teng and H. I. Man (Appl. Phys. Lett. 56, 1734 [1990]) measurement technique is illustrated by the characterization of films of a new high glass transition temperature polyurea. Measurements taken in the transmission mode are shown to be free from non‐negligible errors introduced by interference effects present in standard reflection geometry measurements.

Structural study of a new Langmuir-Blodgett material designed for nonlinear optical applications

A new bifunctional material, [2‐nitro‐5‐(N‐methyl‐N‐octadecylamino)benzoic acid] (NMOB), has been synthesized and its film forming properties investigated by the Langmuir–Blodgett technique. Pressure‐area isotherms indicate that NMOB forms stable monolayers below 40 mN/m which can be transferred to solid substrates. Multilayered samples were prepared on both transmission and reflection substrates and investigated by Fourier transform infrared (FTIR) spectroscopy. Polarization measurements indicate that the orientation of the NMOB molecules is definitely anisotropic with the alkyl tail tilted considerably relative to the surface while the dye chromophore has its plane oriented primarily parallel to the surface. Changes in this orientation upon interleaving these NMOB layers with deuterated cadmium arachidate spacer layers were also investigated both at room and elevated temperatures.

Nonlinear optical polymeric waveguide electro-optic phase modulator

Three nonlinear optical polymeric systems based on nonlinear optical chromophores attached as side chains to poly(methyl methacrylate) were synthesized and their nonlinear optical properties measured in thin film form by second harmonic generation and by the electro-optic effect. Also, attenuation of light propagation in optical waveguides and photothermal deflection infrared spectra were measured on these films to aid in selecting the best system for device development. Based on these results, a phase modulator was constructed and with sub- carrier multiplexing the signals from five TV channels were placed on an infrared laser beam as sidebands. After a short transmission through space, these signals were then heterodyne detected and displayed on a TV monitor with good signal to noise and with no crosstalk.

Optical data storage enters a new dimension

IN THE era of the Internet, massive amounts of information and multimedia have become easily accessible in every corner of the world. The decreasing cost of storing data, and the increasing storage capacities of ever smaller devices. have been key enablers of this revolution. Current storage needs are being met because improvements in conventional technologies – such as magnetic hard-disk drives, optical disks and semiconductor memories – have been able to keep pace with the demand for greater and faster storage.

Polymeric electro-optic phase modulator for broadband data transmission

Polymeric traveling-wave phase modulators have been fabricated to assess the applicability of organic devices as the external modulating elements in coherent optical communication systems. The organic nonlinear optical material in our device was a PMMA-DR1 pendant side-chain polymer. The electrode geometry, used to drive the 1 cm long active region, consisted of a microstrip electrode on top of a poled single transverse mode channel waveguide made by photobleaching at a visible wavelength. This modulator, for which a 3 dB bandwidth in excess of 1 GHz has been demonstrated, was used to transmit a color television signal in a simulated communication system operating at 1.32 micrometers .

Characterization of low-loss polymer modulators fabricated by laser ablation

Electro-optic (EO) channel waveguide polymer phase modulators made by laser ablation are described. The ablation technique is capable of forming low loss channel waveguides at rapid rates with endface quality suitable for fiber pigtailed devices. Loss measurements as well as SEM micrographs were taken to optimize this process. Optical losses of these channel waveguides (before poling) were measured to be 0.37 dB/cm (TM mode) and 0.33 dB/cm (TE mode) at 1.32 micrometers wavelength. The polymer used as poly(methyl methacrylate) with disperse Red 1 dye attached as a side chain at a concentration of 10 mole %. In the poled channel waveguide phase modulator, an EO coefficient (r33) of 10.5 pm/V was achieved with electrode poling and measured by a heterodyne detection system.