Michael E. DeRosa

Photothermal behavior of an optical path adhesive used for photonics applications at 1550 nm

A theoretical and experimental study of photothermal behavior in a commercially available optical path adhesive is described. Photothermal effects were examined for cw and pulsed laser radiation (approximately 1 micros) at 1550 nm. A fiber-optic backreflection technique was used to measure the thermo-optic glass transition temperature of the adhesive. This transition temperature was then used to calibrate fiber-optic photothermal blooming and backreflection pump-probe experiments. Simple thermal models predict DT at 300 mW (cw) to be 65 degrees C and 53 degrees C at 100 W (pulsed). Experimental results are in reasonable agreement with theoretical predictions. The characteristic photothermal relaxation time after a 1-mus pulse for optical path adhesives is found to be 166 micros at the end of a fiber where the mode field diameter is 10.5 micron. Photothermally induced temperatures were found to be below the thermal degradation temperature of the adhesive even at powers as high as 1 W (cw) or 100 W (pulse).

Fiber-optic power limiter based on photothermal defocusing in an optical polymer

We describe the performance of a fiber-optic power-limiting component. The passive device is dynamically responsive to the input signal and has been shown to attenuate continuous-wave power with a dynamic range of up to 9 dB at 150 mW of input power at 1550 nm. The limiting threshold is approximately 30 mW from 1530 to 1565 nm and less than 10 mW at 1430 nm. The device is activated by a photothermal defocusing mechanism in an optical polymer fixed between two expanded core fibers that collimate light through the material. The magitude and threshold of the limiting response is dependent on the absorption properties of the polymer and the size of the gap between the two fiber endfaces. Simple model calculations have been made to predict the limiting response, and they agree reasonably well with the performance of the actual device.

Flexible Microfluidic Devices With Three-Dimensional Interconnected Microporous Walls

Microfluidics is emerging as one of the fastest growing fields for chemical and biological applications. The demand has also increased for methods of fabricating low-cost prototype microfluidic devices rapidly with compatible materials and novel functional attributes. One attractive feature that can be incorporated into microfluidic devices is a porous membrane or porous channel wall [1]. Devices with such features can potentially be used for multiphase catalytic reactions in chemical and pharmaceutical applications similar to the gas-liquid-solid hydrogenation reactions reported by Kobayahi et al. [2] or gas-liquid syntheses by Park and Kim [3].Copyright

Evaluation of optical path adhesive's behavior in high-power photonics applications

In this paper we present the result of a sensitive experimental technique used to provide information about the limitations of using organic polymers for fiber-optic high power applications. Optical path adhesives are commonly used in fiber optics assemblies due to their mechanical and optical properties. However, their use in high power applications creates certain concerns about short-term and long-term stability of the adhesive material. We developed an approach for evaluating the effects of high power in optical path adhesives used in applications for fiber-optic devices. We extended far field experimental technique for analysis on a thin polymer layer placed on the tip of an optical fiber exposed to a wide range of optical powers. We found that this technique can be used for both thermo-optical effects evaluation and electronic non-linear contributions to the refractive index of the material. We show how this method permits separation of these two effects, and long term behavior of polymer materials in such applications. This approach could be used for evaluation of wide range polymer materials in photonics.