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Full-Text Articles in Physics
Hydrogen Donors And Ti3+ Ions In Reduced Tio2 Crystals, A. T. Brant, Shan Yang (杨山), Nancy C. Giles, Larry E. Halliburton
Hydrogen Donors And Ti3+ Ions In Reduced Tio2 Crystals, A. T. Brant, Shan Yang (杨山), Nancy C. Giles, Larry E. Halliburton
Faculty Publications
Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) are used to identify and characterize the neutral hydrogen donor in TiO2 crystals having the rutile structure. These spectra are best observed near 5 K. The neutral donors are present without photoexcitation in crystals that have been slightly reduced at high temperature in a nitrogen atmosphere. The same defects can be photoinduced at low temperature in oxidized crystals. The neutral hydrogen donor in this lattice consists of a substitutional Ti3+ ion adjacent to a substitutional OH– molecular ion. The axis of the OH– molecule lies in the …
Ir Nonlinear Absorption Leading To Laser-Induced Damage In Ge & Gasb, Torrey J. Wagner, Matthew J. Bohn, Ronald A. Coutu Jr., L. P. Gonzales, J. M. Murray, K. L. Schepler, S. Guha
Ir Nonlinear Absorption Leading To Laser-Induced Damage In Ge & Gasb, Torrey J. Wagner, Matthew J. Bohn, Ronald A. Coutu Jr., L. P. Gonzales, J. M. Murray, K. L. Schepler, S. Guha
Faculty Publications
Using a simultaneous fitting technique to extract nonlinear absorption coefficients from data at two pulse widths, we measure two-photon and free-carrier absorption coefficients for Ge and GaSb at 2.05 and 2.5 μm for the first time. Results agreed well with published theory. Single-shot damage thresholds were also measured at 2.5 μm and agreed well with modeled thresholds using experimentally determined parameters including nonlinear absorption coefficients and temperature dependent linear absorption. The damage threshold for a single-layer Al2O3 anti-reflective coating on Ge was 55% or 35% lower than the uncoated threshold for ps or ns pulses, respectively. Wavelength-dependant …
Complementary Metal-Oxide Semiconductor-Compatible Detector Materials With Enhanced 1550 Nm Responsivity Via Sn-Doping Of Ge/Si(100), Richard T. Beeler, Jay Mathews, Mee-Yi Ryu, Yung-Kee Yeo, Jose Menendez, John Kouvetakis
Complementary Metal-Oxide Semiconductor-Compatible Detector Materials With Enhanced 1550 Nm Responsivity Via Sn-Doping Of Ge/Si(100), Richard T. Beeler, Jay Mathews, Mee-Yi Ryu, Yung-Kee Yeo, Jose Menendez, John Kouvetakis
Faculty Publications
Previously developed methods used to grow Ge1−ySny alloys on Si are extended to Sn concentrations in the 1019−1020 cm−3 range. These concentrations are shown to be sufficient to engineer large increases in the responsivity of detectors operating at 1550 nm. The dopant levels of Sn are incorporated at temperatures in the 370–390 °C range, yielding atomically smooth layers devoid of threading defects at high growth rates of 15–30 nm/min. These conditions are far more compatible with complementary metal-oxide semiconductor processing than the high growth and processing temperatures required to achieve the same …
Oxygen Vacancies Adjacent To Cu(2+) Ions In Tio(2) (Rutile) Crystals, A. T. Brant, Shan Yang (杨山), Nancy C. Giles, Zafar Iqbal, A. Manivannan, Larry E. Halliburton
Oxygen Vacancies Adjacent To Cu(2+) Ions In Tio(2) (Rutile) Crystals, A. T. Brant, Shan Yang (杨山), Nancy C. Giles, Zafar Iqbal, A. Manivannan, Larry E. Halliburton
Faculty Publications
Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) are used to characterize Cu2+ ions substituting for Ti4+ ions in nominally undoped TiO2 crystals having the rutile structure. Illumination at 25 K with 442 nm laser light reduces the concentration of Cu2+ ions by more than a factor of 2. The laser light also reduces the EPR signals from Fe3+ and Cr3+ ions and introduces signals from Ti3+ ions. Warming in the dark to room temperature restores the crystal to its preilluminated state. Monitoring the recovery of the photoinduced changes in the Cu …
Energy Scaling Of Nanosecond Gain-Switched Cr2+:Znse Lasers, Vladimir V. Fedorov, Igor S. Moskalev, M. S. Mirov, S. B. Mirov, Torrey J. Wagner, Matthew J. Bohn, Patrick A. Berry, K. L. Schepler
Energy Scaling Of Nanosecond Gain-Switched Cr2+:Znse Lasers, Vladimir V. Fedorov, Igor S. Moskalev, M. S. Mirov, S. B. Mirov, Torrey J. Wagner, Matthew J. Bohn, Patrick A. Berry, K. L. Schepler
Faculty Publications
In this paper, we report record nanosecond output energies of gain-switched CrZnSe lasers pumped by Q-switched CrTmHoYAG 100 ns at 2.096 microns and Raman shifted NdYAG lasers 7 ns at 1.906 microns. In these experiments we used Brewster cut CrZnSe gain elements with a chromium concentration of 8x1018cm-3. Under CrTmHoYAG pumping, the first CrZnSe laser demonstrated 3.1 mJ of output energy, 52 slope efficiency and 110 nm linewidth centered at a wavelength of 2.47 microns. Maximum output energy of the second CrZnSe laser reached 10.1 mJ under H2 Raman shifted NdYAG laser pumping. The slope …
Kinetic Solution Of The Structure Of A Shock Wave In A Nonreactive Gas Mixture, Eswar Josyula, Prakash Vedula, William F. Bailey, Casmir J. Suchyta Iii
Kinetic Solution Of The Structure Of A Shock Wave In A Nonreactive Gas Mixture, Eswar Josyula, Prakash Vedula, William F. Bailey, Casmir J. Suchyta Iii
Faculty Publications
The multispecies Boltzmann equation is numerically integrated to characterize the internal structure of a Mach 3 shock wave in a hard sphere gas. The collision integral is evaluated by the conservative discrete ordinate method [F. G. Tcheremissine, Comput. Math. Math. Phys. 46, 315 (2006)]. There was excellent agreement of macroscopic variables [Kosuge et al., Eur. J. Mech. B/Fluids 20, 87 (2001)]. The effect of species concentration and mass ratio on the behavior of macroscopic variables and distribution functions in the structure of the shock wave is considered for both two- and three-species gas mixtures. In a binary mixture of gases …