The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Pallab Bhattacharya - One of the best experts on this subject based on the ideXlab platform.
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small signal modulation and Differential Gain of red emitting λ 630 nm ingan gan quantum dot lasers
Applied Physics Letters, 2013Co-Authors: Thomas Frost, Animesh Banerjee, Pallab BhattacharyaAbstract:We report small-signal modulation bandwidth and Differential Gain measurements of a ridge waveguide In0.4Ga0.6N/GaN quantum dot laser grown by molecular beam epitaxy. The laser peak emission is at λ = 630 nm. The −3 dB bandwidth of an 800 μm long device was measured to be 2.4 GHz at 250 mA under pulsed biasing, demonstrating the possibility of high-speed operation of these devices. The Differential Gain was measured to be 5.3 × 10−17 cm2, and a Gain compression factor of 2.87 × 10−17 cm3 is also derived from the small-signal modulation response.
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continuous wave operation and Differential Gain of ingan gan quantum dot ridge waveguide lasers λ 420 nm on c plane gan substrate
Applied Physics Letters, 2012Co-Authors: Animesh Banerjee, Ethan Stark, Thomas Frost, Pallab BhattacharyaAbstract:The Differential Gain and coherent output characteristics of blue-emitting In0.18Ga0.82N/GaN quantum dot ridge waveguide lasers have been measured. The laser heterostructures were grown by molecular beam epitaxy. Injected carrier lifetimes in the quantum dots have been measured by temperature dependent and time resolved photoluminescence measurements. The radiative lifetime at 280 K is 480 ps. The threshold current densities at room temperature are 930 and 970 A/cm2 for pulsed and continuous wave bias operation, respectively. The measured Differential Gain is 2 × 10−16 cm2. The output slope and wall plug efficiency at 1050 A/cm2 under continuous wave operation are 0.4 W/A and 0.4%, respectively. The measured blue shift in the emission wavelength due to screening of the piezoelectric field with injection is as small as 4.4 nm.
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characteristics of a high speed 1 22 μm tunnel injection p doped quantum dot excited state laser
Applied Physics Letters, 2011Co-Authors: Pallab Bhattacharya, Thomas FrostAbstract:The measured characteristics of excited state lasing in tunnel injection p-doped InAs quantum dot lasers are reported. Excited state lasing at 1.22 μm is ensured by a high-reflectivity facet coating which is designed to suppress ground state lasing in the devices. The saturation modal Gain in the excited states is 56 cm−1, which is a factor of ∼2.5 higher than that of the ground state. The small-signal modulation bandwidth for I=4.5Ith is 13.5 GHz and the Differential Gain is 1.1×10−15 cm2.
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small signal modulation and Differential Gain of single mode self organized in0 4ga0 6as gaas quantum dot lasers
Applied Physics Letters, 1997Co-Authors: K Kamath, J D Phillips, Hongtao Jiang, J Singh, Pallab BhattacharyaAbstract:We report small-signal modulation bandwidth and Differential Gain measurements of a single-layer self-organized In0.4Ga0.6As/GaAs quantum dot laser grown by molecular beam epitaxy. The 3 dB bandwidth of single-mode ridge waveguide lasers was measured to be 7.5 GHz at 100 mA under pulsed measurements, demonstrating the possibility of high speed operation of these devices. The Differential Gain was measured to be 1.7×10−14 cm2.
L Shterengas - One of the best experts on this subject based on the ideXlab platform.
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high power 2 2 mu m diode lasers with heavily strained active region
IEEE Photonics Technology Letters, 2011Co-Authors: Rui Liang, L Shterengas, Gela Kipshidze, Jianfeng Chen, D Westerfeld, G BelenkyAbstract:High-power 2.2-μm diode lasers and their arrays were designed and fabricated. Laser heterostructures were grown using solid-source molecular beam epitaxy on GaSb substrates. The device active regions contained two 1.5% compressively strained GainAsSb quantum wells. Heavy compressive strain in the active region ensured strong carrier confinement and high Differential Gain. A broadened waveguide design approach was utilized to obtain an internal optical loss below 4 cm-1 and a threshold current density below 100 A/cm2. Individual high-power lasers produced 1.6 W of continuous-wave (CW) multimode power at room temperature from a single 100-μm-wide aperture. Linear laser arrays generated more than 25 W of quasi-continuous wave output power. The device power conversion efficiencies were better than 20% in peak and above 10% at maximum output power level.
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diode lasers emitting at 3 μm with 300 mw of continuous wave output power
Electronics Letters, 2009Co-Authors: L Shterengas, Gela Kipshidze, Takashi Hosoda, Jiannjong Chen, G BelenkyAbstract:Type-I double-quantum-well GaSb-based diode lasers operating at 3 mum with room-temperature continuous-wave output power above 300 mW and peak power-conversion efficiency near 8 were designed and fabricated. Laser heterostructure comprised quinary AlGainAsSb alloy as barrier and waveguide material. Use of quinary alloy resulted in adequate hole confinement. The waveguide thickness was chosen to maximise modal Differential Gain. Continuous-wave threshold current density about 100 A/cm 2 per quantum-well and slope efficiency of 100 mW/A were demonstrated at 17degC.
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effect of quantum well compressive strain above 1 on Differential Gain and threshold current density in type i gasb based diode lasers
IEEE Journal of Quantum Electronics, 2008Co-Authors: Jianfeng Chen, L Shterengas, Gela Kipshidze, Dmitry Donetsky, Mikhail V Kisin, G BelenkyAbstract:InGaAsSb/AlGaAsSb quantum well (QW) diode laser structures with either 1% or 1.5% compressively strained QWs were grown on GaSb substrates by molecular beam epitaxy. Wide-stripe lasers fabricated from structures of both types have room-temperature operating wavelengths near 2.3 microns. The room-temperature threshold current density of 1-mm-long uncoated devices with 1.5% strained QWs was lower than threshold current density of the 1.0% strained QW devices by nearly a factor of two (120 A/cm2 versus 230 A/cm2 ). Experiment shows that the reduction in threshold current density with increasing QW strain is related to the increase in Differential Gain and decrease in transparency current density. Optical Gain calculations prove that improvement of the QW hole confinement reduces the threshold carrier concentration in laser structures with heavily strained low arsenic content quantum wells.
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continuous wave operation of diode lasers at 3 36μm at 12 c
Applied Physics Letters, 2008Co-Authors: L Shterengas, Gela Kipshidze, Takashi Hosoda, G Belenky, S SuchalkinAbstract:GaSb-based type-I quantum-well diode lasers emitting at 3.36μm at 12°C with 15mW of continuous wave output power are reported. Devices with two or four InGaAsSb compressively strained quantum wells and AlInGaAsSb quinternary barriers were fabricated and characterized. It was shown that increase in the quantum-well number led to improved laser Differential Gain and reduced threshold current.
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high power 2 4μm heavily strained type i quantum well gasb based diode lasers with more than 1w of continuous wave output power and a maximum power conversion efficiency of 17 5
Applied Physics Letters, 2007Co-Authors: L Shterengas, G Belenky, Mikhail V Kisin, D DonetskyAbstract:The authors demonstrate a double quantum well GaSb-based diode laser operating at 2.4μm with a room-temperature cw output power of 1050mW and a maximum power-conversion efficiency of 17.5%. Laser Differential Gain with respect to current increases by a factor of 2 and laser threshold current is nearly halved when the compressive strain in the quantum wells is increased from 1.2% to 1.6%. This improvement is due to substantially improved hole confinement in the heavily compressively strained active region.
G Belenky - One of the best experts on this subject based on the ideXlab platform.
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diode lasers emitting at 3 μm with 300 mw of continuous wave output power
Electronics Letters, 2009Co-Authors: L Shterengas, Gela Kipshidze, Takashi Hosoda, Jiannjong Chen, G BelenkyAbstract:Type-I double-quantum-well GaSb-based diode lasers operating at 3 mum with room-temperature continuous-wave output power above 300 mW and peak power-conversion efficiency near 8 were designed and fabricated. Laser heterostructure comprised quinary AlGainAsSb alloy as barrier and waveguide material. Use of quinary alloy resulted in adequate hole confinement. The waveguide thickness was chosen to maximise modal Differential Gain. Continuous-wave threshold current density about 100 A/cm 2 per quantum-well and slope efficiency of 100 mW/A were demonstrated at 17degC.
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effect of quantum well compressive strain above 1 on Differential Gain and threshold current density in type i gasb based diode lasers
IEEE Journal of Quantum Electronics, 2008Co-Authors: Jianfeng Chen, L Shterengas, Gela Kipshidze, Dmitry Donetsky, Mikhail V Kisin, G BelenkyAbstract:InGaAsSb/AlGaAsSb quantum well (QW) diode laser structures with either 1% or 1.5% compressively strained QWs were grown on GaSb substrates by molecular beam epitaxy. Wide-stripe lasers fabricated from structures of both types have room-temperature operating wavelengths near 2.3 microns. The room-temperature threshold current density of 1-mm-long uncoated devices with 1.5% strained QWs was lower than threshold current density of the 1.0% strained QW devices by nearly a factor of two (120 A/cm2 versus 230 A/cm2 ). Experiment shows that the reduction in threshold current density with increasing QW strain is related to the increase in Differential Gain and decrease in transparency current density. Optical Gain calculations prove that improvement of the QW hole confinement reduces the threshold carrier concentration in laser structures with heavily strained low arsenic content quantum wells.
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continuous wave operation of diode lasers at 3 36μm at 12 c
Applied Physics Letters, 2008Co-Authors: L Shterengas, Gela Kipshidze, Takashi Hosoda, G Belenky, S SuchalkinAbstract:GaSb-based type-I quantum-well diode lasers emitting at 3.36μm at 12°C with 15mW of continuous wave output power are reported. Devices with two or four InGaAsSb compressively strained quantum wells and AlInGaAsSb quinternary barriers were fabricated and characterized. It was shown that increase in the quantum-well number led to improved laser Differential Gain and reduced threshold current.
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high power 2 4μm heavily strained type i quantum well gasb based diode lasers with more than 1w of continuous wave output power and a maximum power conversion efficiency of 17 5
Applied Physics Letters, 2007Co-Authors: L Shterengas, G Belenky, Mikhail V Kisin, D DonetskyAbstract:The authors demonstrate a double quantum well GaSb-based diode laser operating at 2.4μm with a room-temperature cw output power of 1050mW and a maximum power-conversion efficiency of 17.5%. Laser Differential Gain with respect to current increases by a factor of 2 and laser threshold current is nearly halved when the compressive strain in the quantum wells is increased from 1.2% to 1.6%. This improvement is due to substantially improved hole confinement in the heavily compressively strained active region.
P Bhattacharya - One of the best experts on this subject based on the ideXlab platform.
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dynamic characteristics of high speed in0 4ga0 6as gaas self organized quantum dot lasers at room temperature
Applied Physics Letters, 2002Co-Authors: S Ghosh, S Pradhan, P BhattacharyaAbstract:We have measured the room-temperature modulation characteristics of self-organized In0.4Ga0.6As/GaAs quantum dot lasers in which electrons are injected into the dot lasing states by tunneling. A small-signal modulation bandwidth of f−3 dB=22 GHz is measured. Values of Differential Gain at 288 K of dg/dn≅8.85×10−14 cm2 and Gain compression factor e=7.2×10−16 cm3 are derived from the modulation data. Extremely low values of linewidth enhancement factor α∼1 and chirp <0.6 A were also measured in the devices.
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tunnel injection in0 4ga0 6as gaas quantum dot lasers with 15 ghz modulation bandwidth at room temperature
Applied Physics Letters, 2002Co-Authors: P Bhattacharya, S GhoshAbstract:By utilizing tunnel injection of electrons, first demonstrated in quantum well lasers, we have measured enhanced small-signal modulation bandwidth, f−3dB, and reduced temperature sensitivity of the threshold current, characterized by T0, in In0.4Ga0.6As/GaAs self-organized quantum dot ridge waveguide lasers. Values of f−3dB=15 GHz at 283 K and T0=237 K for 318⩾T⩾278 are measured in these devices. The Differential Gain at 283 K is dg/dn≅8.5×10−14 cm2 and the Gain compression factor e=4.5×10−17 cm3.
S Ghosh - One of the best experts on this subject based on the ideXlab platform.
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dynamic characteristics of high speed in0 4ga0 6as gaas self organized quantum dot lasers at room temperature
Applied Physics Letters, 2002Co-Authors: S Ghosh, S Pradhan, P BhattacharyaAbstract:We have measured the room-temperature modulation characteristics of self-organized In0.4Ga0.6As/GaAs quantum dot lasers in which electrons are injected into the dot lasing states by tunneling. A small-signal modulation bandwidth of f−3 dB=22 GHz is measured. Values of Differential Gain at 288 K of dg/dn≅8.85×10−14 cm2 and Gain compression factor e=7.2×10−16 cm3 are derived from the modulation data. Extremely low values of linewidth enhancement factor α∼1 and chirp <0.6 A were also measured in the devices.
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tunnel injection in0 4ga0 6as gaas quantum dot lasers with 15 ghz modulation bandwidth at room temperature
Applied Physics Letters, 2002Co-Authors: P Bhattacharya, S GhoshAbstract:By utilizing tunnel injection of electrons, first demonstrated in quantum well lasers, we have measured enhanced small-signal modulation bandwidth, f−3dB, and reduced temperature sensitivity of the threshold current, characterized by T0, in In0.4Ga0.6As/GaAs self-organized quantum dot ridge waveguide lasers. Values of f−3dB=15 GHz at 283 K and T0=237 K for 318⩾T⩾278 are measured in these devices. The Differential Gain at 283 K is dg/dn≅8.5×10−14 cm2 and the Gain compression factor e=4.5×10−17 cm3.