Darnell E. Diggs

DNA Photonics [Deoxyribonucleic Acid]

ABSTRACT Purified deoxyribonucleic acid (DNA) derived from salmon and scallop sperm has demonstrated excellent passive and active optical properties. Characterization of the optical and electromagnetic properties of DNA suggests suitability for photonic applications. One of interesting features of DNA we discovered was an intercalation of aromatic compounds into stacked layers within the double helix of DNA molecules. We found that various optical dyes inserted into the double helix of DNA molecules rendered active optical waveguide materials with excellent nonlinear optical properties. Our research included the investigation of DNA for use as an optical waveguide material as well as intercalation of fluorescent dyes, photochromic dyes, nonlinear optic chromophores, two photon dyes and rare earth compounds into DNA for use as a nonlinear optical material.

THz generation from InN films due to destructive interference between optical rectification and photocurrent surge

We have investigated the characteristics of THz generation including the dependence of the output power and polarization on the incident angle and pump polarization from two series of InN films grown by plasma-assisted molecular beam epitaxy (PAMBE) and metal organic chemical vapor deposition (MOCVD), respectively. Following the analyses of our results, we have attributed the mechanism of the THz generation from these InN samples to the destructive interference between optical rectification and photocurrent surge. Under the average intensity of 176 W cm−2 for the subpicosecond laser pulses at 782 nm, the THz output powers were measured to be as high as 2.4 µW from the 220 nm InN film, with the output frequencies spanning the band from 300 GHz to 2.5 THz.

Deoxyribonucleic acid (DNA) cladding layers for nonlinear-optic-polymer-based electro-optic devices

Nonlinear optic (NLO) polymer based electro-optic devices have been achieving world record low half wave voltages and high frequencies over the last 2-3 years. Part of the advancement is through the use of relatively more conductive polymers for the cladding layers. Based on the current materials available for these cladding materials, however, the desired optical and electromagnetic properites are being balanced for materials processability. One does not want the solvent present in one layer to dissovle the one deposited underneath, or be dissolved by the one being deposited on top. Optimized polymer cladding materials, to further enhance device performance, are continuing to be investigated. Thin films of deoxyribonucleic acid (DNA), derived from salmon sperm, show promise in providing both the desired optical and magnetic properties, as well as the desired resistance to various solvents used for NLO polymer device fabrication. Thin films of DNA were deposited on glass and silicon substrates and the film quality, optical and electromagnetic properties and resistance to various solvents were characterized.

Development of chemical sensors using polymer optical waveguides fabricated with DNA

A number of studies are currently focused on using polymers derived from salmon DNA as the primary ingredient in the design of optical waveguide devices. Although the long term goal is to develop optical devices for rapid chemical and biosensing, this work was aimed specifically at studying the response of a planar DNA waveguide to ammonia in nitrogen and air with controlled amounts of humidity at ambient temperatures. This follows the work of S. S. Sarkisov et al. who used PMMA and other polymer films doped with the indicator dye bromocresol purple (BCP). These devices are characterized by absorption sensitivities of the order 0.1 dB attenuation of the transmitted light signal per 100 ppm change in the NH3 concentration with response times of better than 1 ms and can be recycled with no loss of sensitivity. The performances of waveguide devices using films fabricated with high and low molecular weight DNA with BCP are compared to BCP-doped PMMA devices.

DNA- new class of polymer

Suitable organic and polymeric based materials for electronic and photonic applications must possess the desired electromagnetic and optical properties to achieve optimal device performance in order to be more competitive with their inorganic counterparts. A new class of biopolymer, processed from purified marine-based deoxyribonucleic acid (DNA), has been investigated for use in both electronic and photonic applications and has demonstrated promise as an excellent dielectric and optical waveguide material. In this paper we present examples of devices using this new DNA-based biopolymer.

DNA-based materials for electro-optic applications : current status

Purified deoxyribonucleic acid (DNA), derived from salmon milt and roe sacs, waste products of the Japanese fishing industry in Hokkaido, has been processed into a promising, optical waveguide quality, biopolymer material suitable for both passive and active optical and electro-optic applications. Intercalation of aromatic compounds into stacked layers within the double helix of DNA molecules has rendered active optical waveguide materials with excellent nonlinear optical properties.

Deoxyribonucleic acid (DNA)-based nonlinear optics

Highly purified deoxyribonucleic acid (DNA) was isolated from salmon and scallop sperm by an enzymatic isolation process. Characterization of the optical and electromagnetic properties of DNA suggested suitability for optical waveguide applications. One of the characteristic features of DNA we discovered was an intercalation of aromatic compounds into stacked layers within the double helix of DNA molecules. We found that various optical dyes inserted into the double helix of DNA molecules render optical waveguide films of dye-intercalated DNA suitable for active photonic devices. Our investigation includes intercalation of fluorescent dyes, photochromic dyes, nonlinear optic chromophores, two photon dyes and rare earth compounds into DNA comparing results with poly(methyl methacrylate) (PMMA) based materials.

Deoxyribonucleic acid (DNA)-based optical materials

Optical materials for waveguiding applications must possess the desired optical and electromagnetic properties for optimal device performance. Purified deoxyribonucleic acid (DNA), derived from salmon sperm, has been investigated for use as an optical waveguide material. In this paper we present the materials processing and optical and electromagnetic characterization of this purified DNA to render a high quality, low loss optical waveguide material.

Planar optical waveguide sensor of ammonia

We describe a novel sensor of ammonia based on a planar optical waveguide made of a thin film of polymer polyimide doped with indicator dye bromocresol purple. The film of dye-doped polyimide demonstrated reversible increase of absorption with a peak near 600 nm in response to presence of ammonia in ambient air. Coupling of input and output optic fibers with the waveguide was done by means of coupling prisms or coupling grooves. The latter configuration has the advantage of low cost, less sensitivity to temperature variation, and the possibility of coupling from both sides of the waveguide. Special experimental setup was built to test the sensor. It included test gas chamber with sealed optic fiber feed-throughs, gas filling line, laser source, photodetector, and signal processing hardware and software. The sensor was capable of detecting 100 ppm of ammonia in air within 8 seconds. Further increase of sensitivity can be achieved by adding more dye dopant to the polymer, increase of the length of the waveguide, and suppression of noise. Overexposure of the sensor to more than 5000 ppm of ammonia led to the saturation of the polymer film and, as a result, significant decrease of sensitivity and increase of the response time. The sensor can be used as low cost component of a distributed optical network of chemical sensors for monitoring presence of hazardous industrial pollutants in air.

Nonlinear optic polymer electro-optic modulators for space applications

Optoelectronic devices based on nonlinear optic (NLO) polymers, with electro-optic (EO) coefficients in excess of 100 pm/V at 1.06 μm and dielectric constants of < 3, have demonstrated 100+ GHz data rates with less than 4 volt operating voltages. This has gained interest from the space based applications community, since in addition to being tolerant to a space environment, electro-optic devices for space applications will also need to operate at high data rates and at low operational powers. We have investigated various NLO polymers for core materials as well as passive polymers with various conductivities, both ionic and electronic, suitable for use as optical cladding layers in NLO polymer based opto-electronic devices. Our goal was to find materials that would be tolerant to irradiation as well as maximizing the nonlinearity of the NLO core material, thus minimizing the total applied poling voltage, and minimize the optical absorption loss. Using a cladding material that is more conductive than the NLO core material, the majority of the applied poling voltage is dropped across the core, thus maximizing the EO coefficient with minimum applied voltage or power. We found, however, that it is necessary to balance the optical and electromagnetic properties of the materials with their processability and compatibility.