Electronic circuits alone cannot fully meet future requirements for speed, size, and weight of many sensor systems, such as digital radar technology and as a result, interest in integrated photonic circuits (IPCs) and the hybridization of electronics with photonics is growing. However, many IPC components such as photodetectors are not presently ideal, but germanium has many advantages to enable higher performance designs that can be better incorporated into an IPC. For example, Ge photodetectors offer an enormous responsivity to laser wavelengths near 1.55 mu m at high frequencies to 40GHz, and they can be easily fabricated as part of a planar silicon processing schedule. At the same time, germanium has enormous potential for enabling 1.55 micron lasers on silicon and for enhancing the performance of silicon modulators. Our new effort has begun by studying the deposition of germanium on silicon and beginning to develop methods for processing these films. In initial experiments comparing several common chemical solutions for selective etching under patterned positive photoresist, it was found that hydrogen peroxide (H2O2) at or below room temperature (20 C) produced the sharpest patterns in the Ge films; H2O2 at a higher temperature (50 C) resulted in the greatest lateral etching.

An all guided-wave multi-spectral laser source emitting watts to tens-of-watts of mid-infrared power would impact a broad range of airborne and space applications. As compared with a free-space solid-state laser source, a guided-wave design, composed of coupled lasing and nonlinear optical components, offers potential advantages in size, weight, efficiency, and mechanical robustness while retaining high beam quality for single-mode designs. New material options under development by the Materials and Manufacturing Directorate of the Air Force Research Laboratory (AFRL) enable new approaches to achieving such a source.

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.

THz average output power as high as 2.4 microwatts is generated from InN films, with the mechanism being the interference between optical rectification and photocurrent surge.

We observed that photoluminescence intensities clamped at certain values as the pump intensity was increased, due to the presence of nonlinear degenerate electron gas and saturation of photogenerated and localized holes in InN.

Photopatterning with 266 nm UV light was accomplished on spin-coated DNA thin films using two different techniques. Lithographic masks were used to create 10-100 micron-sized arrays of enhanced hydrophilicity. Two such masks were used: (1) Polka Dot Filter having opaque squares and a transparent grid and (2) A metal wire-mesh having transparent squares and opaque grid. UV light selectively photodissociates the DNA film where it is exposed into smaller more hydrophilic fragments. UV-exposed films are then coated with a solution of a protein. The protein appears to selectively coat over areas exposed to UV light. We have also used interferometric lithography with UV light to accomplish patterning on the scale of 1 micron on DNA thin films. This technique has the potential to generate micro/nano arrays and vary the array-size. This paper describes the fabrication of these microarrays and a plausible application for fabricating antibody arrays for protein sensing applications.

Using descriptive and explanatory research methodologies, researchers have qualitatively investigated factors influential in causing our nation's youth to decide whether to select science, technology, engineering, and mathematics (STEM) as their academic majors. Furthermore, researchers have also examined what causes African American men and women to decide whether they desire to become engineers and scientists. Using preexisting studies numerous themes have emerged from these data, which supports educational outreach as a powerful tool for encouraging our youth to consider the STEM disciplines. This paper highlights Air Force Research Laboratory researchers' efforts in combating the forces that could jeopardize our nation's position as one of the leaders in technology and scientific innovations.

Enhanced electroluminescent efficiency using a deoxyribonucleic acid (DNA)-based biopolymer complex as an electron blocking layer has been demonstrated in both green- and blue-emitting organic light emitting diodes. The resulting bio organic light emitting diodes, or BioLEDs, achieved a maximum luminous efficiency of 8.2 and 0.8 cd/A, respectively, resulting in as much as 10x higher efficiency, 30x brighter output and 3x longer lifetime than their OLED counterparts. In this paper we describe the device fabrication and present the performance of these new structures.

The use of DNA as a functional biomaterial for optical device applications is becoming a fast-expanding technology. Various researchers are investigating salmon DNA as the primary ingredient in the design of optical waveguide devices. The interaction of the indicator dye molecule, Bromocresol Purple (BCP) with the unique homogeneous double helical structure of DNA for potential electro-optic and chemical sensing applications is reported.

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.

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.

We describe novel sensor of ammonia based on a planar optical waveguide made of thin film of polymer polyimide doped with indicator dye bromocresol purple. The film of dyedoped 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 feedthroughs, gas filling line, laser source, photodetector, and signal processing hardware and software. The sensitivity of the sensor was evaluated to be close to 100 ppm of ammonia in air and the time response was about 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 the noise. Overexposure of the sensor to more than 5000 ppm of ammonia led to the saturation of the sensitive film and, as a result, significant decrease of its 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 air pollutants in the exhaust of aircraft/spacecraft propulsion systems.

Deoxyribonucleic acid (DNA) extracted and purified from salmon roe and milt sacs, a waste product of the fishing industry was studied for molecular binding and photoluminescence effects using bromocresol purple (BCP). Since BCP is both water and alcohol soluble it was investigated for binding efficiency in DNA/water solutions and modified DNA-CTMA/butanol solutions. Circular dichroism studies show that there is a maximum binding concentration of BCP in the DNA/water solution at ~5% by weight of BCP:DNA. In contrast, DNA-CTMA/butanol solutions showed increased binding concentrations up through 10wt% BCP:DNA-CTMA. This apparent binding affinity of DNA-CTMA for BCP also resulted in a significantly higher (6x) photoluminescence in thin film form when compared to BCP:PMMA films of the same doping concentration.

The design of two of the components which comprise a smart structure is described. A smart structure is a system that has a sensor, control, and actuator. The two aspects that are discussed are the sensor and actuator. There have been numerous changes made to the basic design of the smart structure components to improve their simplicity and cost efficiency. The novel design of the sensor of ammonia based on a planar optical waveguide made of thin fi lm of polymer polyimide doped with indicat or dye bromocresol purple is explained . This particular sensor is designed to detect the presence of ammonia in ambient air. The film of dye -doped polyimide demonstrated reversible increase of absorption with a pea k near 600 nm in response to presence of ammonia in ambient air. Two advantages of the polymer is that it works at elevated temperatures as high as 300 o C and it can be saturated with water vapor in such a way that our sensor will not be affected by the cha nge in humidity of ambient air. To improve the sensitivity of the sensor the concentration of dye dopant was increased. This gave more than a ten times better sensitivity (1 ppm) . The 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 . Exposing the sensor to more than 5000 ppm of ammonia led to saturation of the sensitive film which causes an increase in response time and a decrease in sensitivity. Also a description of an actuator that uses the principle of the photomechanical effect in polyvinylidene fluoride is detailed. To ach ieve the photothermal bending of strips of polyvinylidene fluoride a laser beam with a few milliwatts of power was used. The force generated by the bending strip of polymer was 10 -4 N, which propelled a 1 g oscillating wheel of a mechanical clock. The freq uency of photomechanical resonance at pulsed illumination was inversely proportional to the length of the strip.

Suitable polymer-based photonic materials must possess the desired optical and electromagnetic properties for optimal device performance depending on the intended application. A new class of polymer, processed from purified deoxyribonucleic acid (DNA), has been investigated for use in photonic applications and has shown promise as an excellent optical waveguide material. In this paper we present the current optical and electronic properties of this new DNA-based biopolymer, including optical loss, temperature stability, refractive index, resistivity, dielectric constant and microwave insertion loss.

We demonstrate theoretically and experimentally that initially Gaussian optical beam (633-nm wavelength) sent through the pi-step phase mask and launched into a thin film of polymer poly(methyl methacrylate) doped with laser dye 4-(Dicyanomethylene)-2-methyl-2-(p-dimethylaminostyrl)4H-pyran known as DCM evolves into a spatial structure similar to the dark spatial soliton This takes place due to the third order nonlinearity associated with the mechanism of unconverted photobleaching of the dye-doped polymer. The result of the structuring of the beam is the formation of a permanent pattern of the refractive index of the film that acts as a channel waveguide trapping a weak Gaussian probe beam coaxial with the main beam. We also demonstrate theoretically the possibility of trapping the probe beam, which propagates in opposite direction at an angle to the main beam. The proposed theoretical model is nonlocal in time and is based on the Shrodinger-type nonlinear propagation equation for the main beam and the propagation equation for the probe beam complemented by the rate equation for the light-induced decrease of the refractive index. The results of this study can find application in optical interconnects and data processing.

Various optical technologies can be implemented in chemical sensing. Sensitive, rugged, and compact systems will be more likely built using interferometric waveguide sensors. Currently existing sensors comprise dual-arm systems with external reference arm, dual-arm devices with internal reference arm such as integrated Mach-Zehnder interferometer, and single-arm systems which employ the interference between different waveguide modes. These latter ones are the most compact and rugged but still sensitive enough to monitor volatile pollutants such as NH3 coming out of industrial refrigerators and fertilizer plants and stocks, NO, NO2, SO2, emitted by industrial burning processes. Single-arm devices in planar waveguide configuration most frequently use two orthogonally polarized modes TE (sub i) and TM (sub i) of the same order i. Sensing effect is based on the difference in propagation conditions for the modes caused by the environment. However, dual-mode single-order interferometers still have relatively low sensitivity with respect to the environment related changes in the waveguide core because of small difference between propagation constants of TE (sub i) and TM (sub i) modes of the same order. Substantial sensitivity improvement without significant complication can be achieved for planar waveguide interferometers using modes of different orders with much greater difference between propagation constants.