George Turner - Academia.edu (original) (raw)

Papers by George Turner

National Science Foundation Award ACI-1445604: Jetstream - A Self-Provisioned, Scalable Science a... more National Science Foundation Award ACI-1445604: Jetstream - A Self-Provisioned, Scalable Science and Engineering Cloud Environment, Craig A. Stewart, IU, Principal Investigator.

Components and Packaging for Laser Systems II, 2016

There are a number of military and commercial applications for high-power laser systems in the mi... more There are a number of military and commercial applications for high-power laser systems in the mid-to-long-infrared wavelength range. By virtue of their demonstrated watt-level performance and wavelength diversity, quantum cascade laser (QCL) and amplifier devices are an excellent choice of emitter for those applications. To realize the power levels of interest, beam combining of arrays of these emitters is required and as a result, array technology must be developed. With this in mind, packaging and thermal management strategies were developed to facilitate the demonstration of a monolithic QCL array operating under CW conditions. Thermal models were constructed and simulations performed to determine the effect of parameters such as array-element ridge width and pitch on gain region temperature rise. The results of the simulations were considered in determining an appropriate QCL array configuration. State-of-the-art micro-impingement cooling along with an electrical distribution scheme comprised of AlN multi-layer technology were integrated into the design. The design of the module allows for individual electrical addressability of the array elements, a method of phase control demonstrated previously for coherent beam combining of diode arrays, along with access to both front and rear facets. Hence, both laser and single-pass amplifier arrays can be accommodated. A module was realized containing a 5 mm cavity length monolithic QCL array comprised of 7 elements on 450 m pitch. An output power of 3.16 W was demonstrated under CW conditions at an emission wavelength of 9 m.

Paradigm and Infrastructure, 2006

Obstetrical & Gynecological Survey, 1952

Grundriß des Bergrechts, 1970

Grundriß des Bergrechts, 1970

Das Verhaltnis des Bergbaues zu den offentlichen Verkehrsanstalten, soweit deren Grundbesitz dem ... more Das Verhaltnis des Bergbaues zu den offentlichen Verkehrsanstalten, soweit deren Grundbesitz dem offentlichen Interesses dient, wird in einer von dem allgemeinen Bergschadensrecht abweichenden Weise geregelt. Im Verhaltnis des Bergbaues zum Grundbesitz hat der Bergbau den Vorrang, im Verhaltnis des Bergbaues zu den offentlichen Verkehrsanstalten dagegen die letzteren.

Journal of Crystal Growth, 2010

Strain-compensated (SC) GaInAs/AlInAs/InP multiple-quantum-well structures and quantum cascade la... more Strain-compensated (SC) GaInAs/AlInAs/InP multiple-quantum-well structures and quantum cascade lasers (QCLs) with strain levels of 1% and as high as 1.5% were grown by organometallic vapor phase epitaxy (OMVPE). The structures were characterized by high-resolution X-ray (HRXRD) diffraction and atomic force microscopy (AFM), and narrow-ridge QCL devices were fabricated. HRXRD and AFM results indicate very high quality materials with narrow satellite peaks, well-defined interference fringes, and a step-flow growth mode for 1% SC materials. A marginal broadening of satellite peaks is measured for 1.5% SC structures, but step-flow growth is maintained. QCLs based on a conventional four-quantumwell double-phonon resonant active region design with nominal 1% SC were grown with doping concentration varied from 1 to 4 Â 10 17 cm À 3 in the active region. The performance of ridge lasers under pulsed conditions is comparable to state-of-the-art results for 4.8 mm devices. QCLs with a novel injectorless four-quantum well QCL design and 1.5% SC operated in pulsed mode at room temperature at 5.5 mm.

Applied Physics Letters, 2013

We demonstrate tapered quantum cascade lasers monolithically integrated with a distributed Bragg ... more We demonstrate tapered quantum cascade lasers monolithically integrated with a distributed Bragg reflector acting as both a wavelength-selective back mirror and a transverse mode filter. Each of the 14 devices operates at a different wavelength between 9.2 and 9.7 lm, where nine devices feature single-mode operation at peak powers between 0.3 and 1.6 W at room temperature. High output power and excellent beam quality with peak brightness values up to 1.6 MW cm À2 sr À1 render these two-terminal devices highly suitable for stand-off spectroscopy applications. V

Eye, 1989

We have treated 26 retinal angiomas of less than 4.5mm in size in 15 eyes using repeated appli ca... more We have treated 26 retinal angiomas of less than 4.5mm in size in 15 eyes using repeated appli cations of contiguous argon blue green laser burns. All except one of the angiomas regressed without a massive exudative response of treatment. Haemorrhage occurred in two cases but only affected the visual outcome in one eye. Traction retinal detachment persisted in 50% of the large angiomas, despite regression of the tumour.

National Science Foundation Award ACI-1445604: Jetstream - A Self-Provisioned, Scalable Science a... more National Science Foundation Award ACI-1445604: Jetstream - A Self-Provisioned, Scalable Science and Engineering Cloud Environment, Craig A. Stewart, IU, Principal Investigator.

Components and Packaging for Laser Systems II, 2016

There are a number of military and commercial applications for high-power laser systems in the mi... more There are a number of military and commercial applications for high-power laser systems in the mid-to-long-infrared wavelength range. By virtue of their demonstrated watt-level performance and wavelength diversity, quantum cascade laser (QCL) and amplifier devices are an excellent choice of emitter for those applications. To realize the power levels of interest, beam combining of arrays of these emitters is required and as a result, array technology must be developed. With this in mind, packaging and thermal management strategies were developed to facilitate the demonstration of a monolithic QCL array operating under CW conditions. Thermal models were constructed and simulations performed to determine the effect of parameters such as array-element ridge width and pitch on gain region temperature rise. The results of the simulations were considered in determining an appropriate QCL array configuration. State-of-the-art micro-impingement cooling along with an electrical distribution scheme comprised of AlN multi-layer technology were integrated into the design. The design of the module allows for individual electrical addressability of the array elements, a method of phase control demonstrated previously for coherent beam combining of diode arrays, along with access to both front and rear facets. Hence, both laser and single-pass amplifier arrays can be accommodated. A module was realized containing a 5 mm cavity length monolithic QCL array comprised of 7 elements on 450 m pitch. An output power of 3.16 W was demonstrated under CW conditions at an emission wavelength of 9 m.

Paradigm and Infrastructure, 2006

Obstetrical & Gynecological Survey, 1952

Grundriß des Bergrechts, 1970

Grundriß des Bergrechts, 1970

Das Verhaltnis des Bergbaues zu den offentlichen Verkehrsanstalten, soweit deren Grundbesitz dem ... more Das Verhaltnis des Bergbaues zu den offentlichen Verkehrsanstalten, soweit deren Grundbesitz dem offentlichen Interesses dient, wird in einer von dem allgemeinen Bergschadensrecht abweichenden Weise geregelt. Im Verhaltnis des Bergbaues zum Grundbesitz hat der Bergbau den Vorrang, im Verhaltnis des Bergbaues zu den offentlichen Verkehrsanstalten dagegen die letzteren.

Journal of Crystal Growth, 2010

Strain-compensated (SC) GaInAs/AlInAs/InP multiple-quantum-well structures and quantum cascade la... more Strain-compensated (SC) GaInAs/AlInAs/InP multiple-quantum-well structures and quantum cascade lasers (QCLs) with strain levels of 1% and as high as 1.5% were grown by organometallic vapor phase epitaxy (OMVPE). The structures were characterized by high-resolution X-ray (HRXRD) diffraction and atomic force microscopy (AFM), and narrow-ridge QCL devices were fabricated. HRXRD and AFM results indicate very high quality materials with narrow satellite peaks, well-defined interference fringes, and a step-flow growth mode for 1% SC materials. A marginal broadening of satellite peaks is measured for 1.5% SC structures, but step-flow growth is maintained. QCLs based on a conventional four-quantumwell double-phonon resonant active region design with nominal 1% SC were grown with doping concentration varied from 1 to 4 Â 10 17 cm À 3 in the active region. The performance of ridge lasers under pulsed conditions is comparable to state-of-the-art results for 4.8 mm devices. QCLs with a novel injectorless four-quantum well QCL design and 1.5% SC operated in pulsed mode at room temperature at 5.5 mm.

Applied Physics Letters, 2013

We demonstrate tapered quantum cascade lasers monolithically integrated with a distributed Bragg ... more We demonstrate tapered quantum cascade lasers monolithically integrated with a distributed Bragg reflector acting as both a wavelength-selective back mirror and a transverse mode filter. Each of the 14 devices operates at a different wavelength between 9.2 and 9.7 lm, where nine devices feature single-mode operation at peak powers between 0.3 and 1.6 W at room temperature. High output power and excellent beam quality with peak brightness values up to 1.6 MW cm À2 sr À1 render these two-terminal devices highly suitable for stand-off spectroscopy applications. V

Eye, 1989

We have treated 26 retinal angiomas of less than 4.5mm in size in 15 eyes using repeated appli ca... more We have treated 26 retinal angiomas of less than 4.5mm in size in 15 eyes using repeated appli cations of contiguous argon blue green laser burns. All except one of the angiomas regressed without a massive exudative response of treatment. Haemorrhage occurred in two cases but only affected the visual outcome in one eye. Traction retinal detachment persisted in 50% of the large angiomas, despite regression of the tumour.