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A KHz Pulsed Laser Detection System was developed employing the concept of charge integration with an electrometer, in the NASA Goddard Space Flight Center, Code 618 Calibration Lab for the purpose of using the pulsed lasers for radiometric calibration. Comparing with traditional trans-impedance (current-voltage conversion) detection systems, the prototype of this system consists of a UV-Enhanced Si detector head, a computer controlled shutter system and a synchronized electrometer. The preliminary characterization work employs light sources running in either CW or pulsed mode. We believe this system is able to overcome the saturation issue when a traditional trans-impedance detection system is used with the pulsed laser light source, especially with high peak-power pulsed lasers operating at kilohertz repetition rates (e.g. Ekspla laser or KHz OPO). The charge integration mechanism is also expected to improve the stability of measurements for a pulsed laser light source overcoming the issue of peak-to-peak stability. We will present the system characterizations including signal-to-noise ratio and uncertainty analysis and compare results against traditional trans-impedance detection systems.

Initiatives to increase the number, persistence, and success of women in physics in the United States reach preteen girls through senior women. Programs exist at both the local and national levels. In addition, researchers have investigated issues related to gender equity in physics and physics education. Anecdotal evidence suggests increased media coverage of the underrepresentation of women in science. All of these efforts are motivated and made more effective by the continued collection and presentation of data on the presence, persistence, and promise of women in physics.

We measured, within 6% accuracy, the nonlinear refractive index (n2) of 10 meter long multimode silica fiber of 17μm core diameter, using a modified induced grating autocorrelation technique (IGA). This measurement technique, based on time-delayed two beam coupling in a photorefractive crystal has been used to accurately measure n2 in short lengths of single mode fibers. For the first time to our knowledge, IGA is used to measure n2 of multimode fiber with a passively modelocked Nd:YVO4 laser operating with a dual-line near 1342 nm.

In vivo experiments are performed to induce temperature elevations in implanted prostatic tumours in mice using 0.1 ml commercially available gold nanorod solution injected into the tumour. Tumour shrinkage studies and histological analyses of tumour cell death are conducted, and the equivalent minutes at 43°C (EM43) for inducing tissue thermal damage are estimated based on temperature elevations during the treatment. It has been shown that the laser heating of 15 minutes in the tumour tissue containing gold nanorods is effective to cause irreversible thermal damage to the tumours, with a low laser irradiance on the tumour surface (1.6 W/cm2). The effectiveness of the heating protocol is demonstrated by tumour shrinkage to 7% of its original volume on the 25th day after the laser treatment and tumour necrosis events observed by histological analyses. The results are consistent with the EM43 distribution estimated by possible temperature elevations during the treatment.