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James Gary Eden - One of the best experts on this subject based on the ideXlab platform.
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Cs-Ar optical amplifier with a Saturation Intensity of 10 kW-cm-2 and single-pass extraction efficiency of 28% at 852.2 nm.
Optics express, 2020Co-Authors: S. J. Park, Andrey E. Mironov, James Gary EdenAbstract:Optical amplification by the stimulated emission of Cs(6p2P3/2)-Ar atomic pairs, observed in pump-probe experiments over a ∼290 GHz-wide spectral region lying to the red of the Cs D2 line (852.1 nm), has been realized by photoexciting thermalized, ground state Cs-Ar atoms in the 834-849 nm wavelength interval. When the gain medium is pumped at the peak of the CsAr B2Σ1/2+←X2Σ1/2+ transition at 836.7 nm, maximum gain occurs between 852.2 nm and 852.3 nm and >28% of the energy stored in the upper laser level is extracted with 8 ns (FWHM) probe pulses in a single pass. From the measured rate of Saturation of the extracted pulse energy with increasing probe Intensity, the product of γ0L and Esat, the Saturation pulse energy, is measured directly to be 400 ± 20 µJ and the lower limit for the Saturation Intensity (Isat) of this amplifier is estimated to be 10 kW-cm−2 at 852.2 nm. Circularly polarizing the optical pump beam increases the optical-to-optical conversion efficiency by 20%, and the storage lifetime of the upper laser level is observed from temporally-resolved gain spectra to be 5 ± 1 ns. Pump excitation spectra also reveal a significant contribution from Ar-Cs-Ar (3-body) photoassociation and suprathermal Ar atoms generated by the dissociation of the CsAr B2Σ1/2+ complex. Multipass-amplifier geometries with broad-bandwidth probe signals are expected to yield upper state energy extraction efficiencies above 50%. This alkali-rare gas amplifier demonstrates the efficiencies available with the storage of energy in, and optical extraction from, excited atomic collision pairs.
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Gain and Saturation Intensity of the green Ho:ZBLAN upconversion fiber amplifier and laser
IEEE Photonics Technology Letters, 2002Co-Authors: E. B. Mejía, A.a. Senin, J.m. Talmadge, James Gary EdenAbstract:The gain and Saturation Intensity of the green Ho-doped fluorozirconate (ZBLAN) glass fiber amplifier and laser, pumped in the red (643 /spl les/ /spl lambda//sub p/ /spl les/ 649 nm; /sup 5/F/sub 5/ /spl larr/ /sup 5/I/sub 8/), have been measured. For a 2.4-/spl mu/m core diameter fiber 45 cm in length, the single-pass gain at 543.4 nm exceeds 12 dB for 90 mW of pump power at 643.5 nm. The Saturation power for the /sup 5/F/sub 4/, /sup 5/S/sub 2/ /spl rarr/ /sup 5/I/sub 8/ lasing transition was determined from gain measurements to be 970 /spl plusmn/ 175 /spl mu/W, which corresponds to a Saturation Intensity of 19.8 /spl plusmn/ 3.5 kW /spl middot/ cm/sup -2/, and a stimulated emission cross section approximately one order of magnitude larger than theoretical estimates.
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Small signal gain and Saturation Intensity of an upconversion-pumped Ho:ZBLAN laser amplifier and oscillator
Summaries of Papers Presented at the Lasers and Electro-Optics. CLEO '02. Technical Diges, 1Co-Authors: A.a. Senin, J.m. Talmadge, James Gary Eden, E. B. MejíaAbstract:Summary form only given. In this paper, we present experimental measurements of the gain and Saturation Intensity for a Ho:ZBLAN fiber amplifier operating in the green. To our knowledge, the Saturation Intensity measurements are the first for any upconversion-pumped fiber oscillator or amplifier. Both of the amplifier parameters reported here are critical to the design of amplifiers for LANs in the visible, for example, and the implications of these results for communications and other applications are discussed.
Mario Dagenais - One of the best experts on this subject based on the ideXlab platform.
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Intermediate Band Challenge in InAs/GaAs Quantum Dot Solar Cell at Cryogenic Temperatures
2019 IEEE 46th Photovoltaic Specialists Conference (PVSC), 2019Co-Authors: Mario DagenaisAbstract:The temperature dependence of the photoluminescence from InAs/GaAs quantum dot solar cell (QDSC) is studied. A modified on-resonance z-scan measurement technique is used to extract the quantum dot Saturation Intensity from room temperature to 170K. The Saturation Intensity appreciably decreases when the temperature is decreased but is still comparable to the sun Intensity at maximum concentration at 170 K. This implies that the energy conversion efficiency of this QDSC, even at 170 K, cannot be enhanced by invoking the concept of an intermediate band solar cell.
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high Saturation Intensity in inas gaas quantum dot solar cells and impact on the realization of the intermediate band concept at room temperature
Applied Physics Letters, 2017Co-Authors: Tian Li, Mario DagenaisAbstract:High optical Saturation Intensity at room temperature is reported for an ensemble of undoped quantum dots. The non-linearity of the light-generated-current under resonant excitation from the valence band to the intermediate band is shown to be made up of two components: a background two-photon absorption term and a resonant optical Saturation term. It is argued that the solar Intensity is much lower than the Saturation intensities involved for the first and second transitions in the intermediate band solar cell under 1-sun illumination and therefore prevents exciting an appreciable amount of population in the terminal level that can be ionized to the continuum and generate an appreciable additional current. This additional current is required for enhancing the energy conversion efficiency of a solar cell based on the intermediate band concept. Operating at cryogenic temperatures leads to a reduction in the Saturation Intensity but it might not be sufficient for increasing the energy conversion efficiency,...
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High Saturation Intensity in InAs/GaAs quantum dot solar cells and impact on the realization of the intermediate band concept at room-temperature
Applied Physics Letters, 2017Co-Authors: Mario DagenaisAbstract:High optical Saturation Intensity at room temperature is reported for an ensemble of undoped quantum dots. The non-linearity of the light-generated-current under resonant excitation from the valence band to the intermediate band is shown to be made up of two components: a background two-photon absorption term and a resonant optical Saturation term. It is argued that the solar Intensity is much lower than the Saturation intensities involved for the first and second transitions in the intermediate band solar cell under 1-sun illumination and therefore prevents exciting an appreciable amount of population in the terminal level that can be ionized to the continuum and generate an appreciable additional current. This additional current is required for enhancing the energy conversion efficiency of a solar cell based on the intermediate band concept. Operating at cryogenic temperatures leads to a reduction in the Saturation Intensity but it might not be sufficient for increasing the energy conversion efficiency,...
Kaige Wang - One of the best experts on this subject based on the ideXlab platform.
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Parametric investigations on the Saturation Intensity of Coumarin 102 for stimulated emission depletion application.
Journal of microscopy, 2018Co-Authors: Haiyun Qin, Wenxuan Zhao, Wei Zhao, Chen Zhang, Xiaoqiang Feng, Shuai Liu, Kaige WangAbstract:Stimulated emission depletion (STED) microscopy performed using continuous-wave (CW) lasers has been investigated and developed by Willig et al. (Nature Methods, 2007, 4(11):915) for nearly a decade. Kuang et al. (Review of Scientific Instruments, 2010, 81:053709) developed the CW STED microscopy technique with 405 nm excitation and 532 nm depletion beams. In their research, Coumarin 102 dye was adopted and was found to be depletable. In this study, a parametric investigation of the depletion of Coumarin 102 dye is carried out experimentally. The influence of the excitation and depletion beam intensities and dye concentrations on the depletion efficiency are studied in detail. The results indicate the following: (1) The highest depletion occurs for the 100 μM Coumarin 102 solution, with a 1.4 μW excitation beam and a 115.3 mW depletion beam. (2) The minimum Saturation Intensity (Is) of STED, that is 13 MW cm-2 , is observed when the Coumarin 102 solution concentration is 10 μM. (3) Is values calculated directly from the depletion power derived with the cross-sectional area due to the full-width-at-half-maximum (FWHM) of the depletion beam show poor accuracy, where Is may be overestimated. Thus, a correction factor for the cross-sectional area is proposed. We also find that Is is not exactly constant for a fixed excitation beam power and dye concentration. This trend indicates that the conventional suppression function η(x)=e- ln (2)ISTED(x)/Is derived from picosecond STED may cause errors in evaluating the depletion process in CW STED microscopy.
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Evaluation of Saturation Intensity based on the FWHM of CW stimulated emission depletion microscopy
Optik, 2018Co-Authors: Haiyun Qin, Wenxuan Zhao, Wei Zhao, Chen Zhang, Yong Liu, Guiren Wang, Kaige WangAbstract:Abstract We propose a numerical method to evaluate the Saturation Intensity of fluorescence, which is a key parameter in determining the spatial resolution of a stimulated emission depletion (STED) microscopy system. The Saturation intensities of four different continuous-wave (CW) STED systems reported from the studies of previous researchers (Willig et al., Nature Methods, 2007, 4, 915–918; Hein et al., PNAS, 2008, 105, 14271–14276; Hotta et al., JACS, 2010, 132, 5021–5023) have been calculated. It is found that pTDI fluorescent dye with a 633-nm excitation beam and a 780-nm depletion beam can provide the smallest Saturation Intensity (or the best depletion effect under the same depletion power) in all four cases. Based on the Saturation Intensity, we revisit the influence of wavefront modulation on the resolution improvement of the STED system. It is found that by applying azimuthally polarized light, the lateral resolution of the STED system could be increased to 26 nm with an improvement of up to 67%.
Haiyun Qin - One of the best experts on this subject based on the ideXlab platform.
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Parametric investigations on the Saturation Intensity of Coumarin 102 for stimulated emission depletion application.
Journal of microscopy, 2018Co-Authors: Haiyun Qin, Wenxuan Zhao, Wei Zhao, Chen Zhang, Xiaoqiang Feng, Shuai Liu, Kaige WangAbstract:Stimulated emission depletion (STED) microscopy performed using continuous-wave (CW) lasers has been investigated and developed by Willig et al. (Nature Methods, 2007, 4(11):915) for nearly a decade. Kuang et al. (Review of Scientific Instruments, 2010, 81:053709) developed the CW STED microscopy technique with 405 nm excitation and 532 nm depletion beams. In their research, Coumarin 102 dye was adopted and was found to be depletable. In this study, a parametric investigation of the depletion of Coumarin 102 dye is carried out experimentally. The influence of the excitation and depletion beam intensities and dye concentrations on the depletion efficiency are studied in detail. The results indicate the following: (1) The highest depletion occurs for the 100 μM Coumarin 102 solution, with a 1.4 μW excitation beam and a 115.3 mW depletion beam. (2) The minimum Saturation Intensity (Is) of STED, that is 13 MW cm-2 , is observed when the Coumarin 102 solution concentration is 10 μM. (3) Is values calculated directly from the depletion power derived with the cross-sectional area due to the full-width-at-half-maximum (FWHM) of the depletion beam show poor accuracy, where Is may be overestimated. Thus, a correction factor for the cross-sectional area is proposed. We also find that Is is not exactly constant for a fixed excitation beam power and dye concentration. This trend indicates that the conventional suppression function η(x)=e- ln (2)ISTED(x)/Is derived from picosecond STED may cause errors in evaluating the depletion process in CW STED microscopy.
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Evaluation of Saturation Intensity based on the FWHM of CW stimulated emission depletion microscopy
Optik, 2018Co-Authors: Haiyun Qin, Wenxuan Zhao, Wei Zhao, Chen Zhang, Yong Liu, Guiren Wang, Kaige WangAbstract:Abstract We propose a numerical method to evaluate the Saturation Intensity of fluorescence, which is a key parameter in determining the spatial resolution of a stimulated emission depletion (STED) microscopy system. The Saturation intensities of four different continuous-wave (CW) STED systems reported from the studies of previous researchers (Willig et al., Nature Methods, 2007, 4, 915–918; Hein et al., PNAS, 2008, 105, 14271–14276; Hotta et al., JACS, 2010, 132, 5021–5023) have been calculated. It is found that pTDI fluorescent dye with a 633-nm excitation beam and a 780-nm depletion beam can provide the smallest Saturation Intensity (or the best depletion effect under the same depletion power) in all four cases. Based on the Saturation Intensity, we revisit the influence of wavefront modulation on the resolution improvement of the STED system. It is found that by applying azimuthally polarized light, the lateral resolution of the STED system could be increased to 26 nm with an improvement of up to 67%.
Hiroshi Ishikawa - One of the best experts on this subject based on the ideXlab platform.
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Understanding the ultra-low intersubband Saturation Intensity in InGaAs-AlAsSb quantum wells
IEEE Journal of Quantum Electronics, 2003Co-Authors: Achanta Venu Gopal, H. Yoshida, Teruo Mozume, Nikolai Georgiev, Takasi Simoyama, Hiroshi IshikawaAbstract:We report a novel intersubband material system based on strained InGaAs-AlAs-AlAsSb quantum wells that exhibits a very low, 3 fJ//spl mu/m/sup 2/, Saturation Intensity and about 2-ps carrier-relaxation time at 1.68 /spl mu/m. We performed a density matrix calculation to estimate the Saturation Intensity by simulating the pulsed excitation conditions of the experiment. These studies indicate slow dephasing time and reduced inhomogeneity as the possible mechanisms for the observed large nonlinearity. A detailed dephasing time calculation shows that rather than the reduction in the electron effective mass in these strained quantum wells (QWs), the effect of enhanced concentration of doped carriers in these QWs with reduced inhomogeneity could be the origin of slow dephasing and the observed large nonlinearity.
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large improvement in intersubband Saturation Intensity in ingaas alassb quantum well
Electronics Letters, 2001Co-Authors: Achanta Venu Gopal, H. Yoshida, Arup Neogi, Teruo Mozume, Nikolai Georgiev, Takasi Simoyama, Osamu Wada, Hiroshi IshikawaAbstract:Wavelength dependence of the intersubband absorption Saturation in InGaAs/AlAsSb quantum wells is presented. Large intersubband nonlinearity at 1.72 /spl mu/m With the estimated Saturation Intensity as low as 4 MW/m/sup 2/ was observed.
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Large improvement in intersubband Saturation Intensity in InGaAs/AlAsSb quantum well
Electronics Letters, 2001Co-Authors: Achanta Venu Gopal, H. Yoshida, Arup Neogi, Teruo Mozume, Nikolai Georgiev, Takasi Simoyama, Osamu Wada, Hiroshi IshikawaAbstract:Wavelength dependence of the intersubband absorption Saturation in InGaAs/AlAsSb quantum wells is presented. Large intersubband nonlinearity at 1.72 /spl mu/m With the estimated Saturation Intensity as low as 4 MW/m/sup 2/ was observed.
