Electrically tunable ring resonators incorporating nematic liquid crystals as cladding layers

We have demonstrated electrical tuning in ring resonators fabricated from silicon-on-insulator wafers by incorporating nematic liquid crystals (NLCs) as the waveguide top and side cladding material. Photolithographically defined electrodes aligned around the ring resonator were used to control the orientation of the NLCs to modulate the cladding refractive index and, hence, the resonant wavelengths of the ring resonator

Combined electromagnetic and photoreaction modeling of CLD-1 photobleaching in polymer microring resonators

By combining a solid-state photoreaction model with the modal solutions of an optical waveguide, we simulate the refractive index change due to the photobleaching of CLD-1 chromophores in an amorphous polycarbonate microring resonator. The simulation agrees well with experimental results. The photobleaching quantum efficiency of the CLD-1 chromophores is determined to be 0.65%. The combined modeling of the electromagnetic wave propagation and photoreaction precisely illustrates the spatial and temporal evolution of the optical properties of the polymer material as manifested in the refractive index and their effects on the modal and physical properties of the optical devices

Towards a millivolt optical modulator with nano-slot waveguides

We describe a class of modulator design involving slot waveguides and electro-optic polymer claddings. Such geometries enable massive enhancement of index tuning when compared to more conventional geometries. We present a semi-analytic method of predicting the index tuning achievable for a given geometry and electro-optic material. Based on these studies, as well as previous experimental results, we show designs for slot waveguide modulators that, when realized in a Mach-Zehnder configuration, will allow for modulation voltages that are orders of magnitude lower than the state of the art. We also discuss experimental results for nano-slot waveguides

Reconfigurable Wavelength-Selective Reflector Consisting of Coupled Polymeric Microring Resonators

We propose and demonstrate a novel reconfigurable wavelength-selective reflector for planar lightwave technology based on coupled microring resonators. Narrow-band reflection and strong side-lobe suppression are demonstrated in an optical polymer device using the Vernier effect

A strategic surety roadmap for high consequence software

A strategic surety roadmap for high consequence software systems developed under the High Integrity Software (HIS) Program at Sandia National Laboratories is presented. Selected research tracks are identified and described detailing current technology and outlining advancements to be pursued over the coming decade to reach HIS goals

Oxygen pressure measurement using singlet oxygen emission

Pressure sensitive paint (PSP) provides a visualization of two-dimensional pressure distributions on airfoil and model automobile surfaces. One type of PSP utilizes platinum tetra(pentafluorophenyl)porphine (PtTFPP) dissolved in a fluoro-polymer film. Since the intense 650 nm triplet emission of PtTFPP is quenched by ground state oxygen, it is possible to measure two-dimensional oxygen concentration from the 650 nm emission intensity using a Stern-Volmer-type relationship. This article reports an alternative luminescence method to measure oxygen concentration based on the porphyrin-sensitized 1270 nm singlet oxygen emission, which can be imaged with an InGaAs near infrared camera. This direct measurement of oxygen emission complements and further validates the oxygen measurement based on PtTFPP phosphorescence quenching. Initial success at obtaining a negative correlation between the 650nm PtTFPP emission and the 1270 nm O_2 emission in solution led us to additional two-dimensional film studies using surfaces coated with PtTFPP, MgTFPP, and H_2TFPP in polymers in a pressure and temperature controlled chamber

Synthesis of Diarylthiobarbituric acid Chromophores with Enhanced Second-order Optical Nonlinearities and Thermal Stability

In summary, the compounds reported here demonstrate that it is possible to design chromophores that simultaneously exhibit large nonlinearity and good thermal stability. Furthermore, with the synthesis of bis(4-hydroxyphenyl)thiobarbituric acid, we believe that it should be possible to covalently incorporate these and other rather nonlinear chromophores into poled polymers at high concentrations. Experiments to test this hypothesis are in progress