The Experts below are selected from a list of 33636 Experts worldwide ranked by ideXlab platform
Daniel F. Feezell - One of the best experts on this subject based on the ideXlab platform.
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high speed nonpolar ingan gan superluminescent diode with 2 5 ghz Modulation Bandwidth
IEEE Photonics Technology Letters, 2020Co-Authors: Arman Rashidi, Ashwin K. Rishinaramangalam, Andrew Aragon, Morteza Monavarian, Changmin Lee, Steven P. Denbaars, Saadat Mishkatulmasabih, Daniel F. FeezellAbstract:We demonstrate a superluminescent diode fabricated on a nonpolar ${m}$ -plane GaN substrate by employing a linearly tapered waveguide design. A high electrical −3dB Modulation Bandwidth ( $f_{\mathbf {3dB}}$ ) of 2.5 GHz at a current density of 30 kA/cm2 is achieved. The high Modulation Bandwidth is attributed to the shorter carrier recombination lifetime, the linear gain curve in the nonpolar ${m}$ -plane quantum wells, and the ability to operate at high current densities while effectively suppressing lasing. We derive a general expression for the −3dB Bandwidth as a function of current density for SLDs using a similar approach to that for laser diodes. The −3dB Bandwidth of a nonpolar superluminescent diode increases exponentially with current density. The experimental results are consistent with the derived expression for $f_{\mathbf {3dB}}$ vs . current density.
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High-Speed Nonpolar InGaN/GaN Superluminescent Diode With 2.5 GHz Modulation Bandwidth
IEEE Photonics Technology Letters, 2020Co-Authors: Arman Rashidi, Ashwin K. Rishinaramangalam, Andrew Aragon, Morteza Monavarian, Changmin Lee, Steven P. Denbaars, Saadat Mishkat-ul-masabih, Daniel F. FeezellAbstract:We demonstrate a superluminescent diode fabricated on a nonpolar ${m}$ -plane GaN substrate by employing a linearly tapered waveguide design. A high electrical −3dB Modulation Bandwidth ( $f_{\mathbf {3dB}}$ ) of 2.5 GHz at a current density of 30 kA/cm2 is achieved. The high Modulation Bandwidth is attributed to the shorter carrier recombination lifetime, the linear gain curve in the nonpolar ${m}$ -plane quantum wells, and the ability to operate at high current densities while effectively suppressing lasing. We derive a general expression for the −3dB Bandwidth as a function of current density for SLDs using a similar approach to that for laser diodes. The −3dB Bandwidth of a nonpolar superluminescent diode increases exponentially with current density. The experimental results are consistent with the derived expression for $f_{\mathbf {3dB}}$ vs . current density.
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Impact of crystal orientation on the Modulation Bandwidth of InGaN/GaN light-emitting diodes
Applied Physics Letters, 2018Co-Authors: Morteza Monavarian, Ashwin K. Rishinaramangalam, Arman Rashidi, Andrew Aragon, Steven P. Denbaars, Daniel F. FeezellAbstract:High-speed InGaN/GaN blue light-emitting diodes (LEDs) are needed for future gigabit-per-second visible-light communication systems. Large LED Modulation Bandwidths are typically achieved at high current densities, with reports close to 1 GHz Bandwidth at current densities ranging from 5 to 10 kA/cm2. However, the internal quantum efficiency (IQE) of InGaN/GaN LEDs is quite low at high current densities due to the well-known efficiency droop phenomenon. Here, we show experimentally that nonpolar and semipolar orientations of GaN enable higher Modulation Bandwidths at low current densities where the IQE is expected to be higher and power dissipation is lower. We experimentally compare the Modulation Bandwidth vs. current density for LEDs on nonpolar (101¯0), semipolar (202¯1¯), and polar 0001 orientations. In agreement with wavefunction overlap considerations, the experimental results indicate a higher Modulation Bandwidth for the nonpolar and semipolar LEDs, especially at relatively low current densities....
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impact of crystal orientation on the Modulation Bandwidth of ingan gan light emitting diodes
Applied Physics Letters, 2018Co-Authors: Morteza Monavarian, Ashwin K. Rishinaramangalam, Arman Rashidi, Andrew Aragon, Steven P. Denbaars, Daniel F. FeezellAbstract:High-speed InGaN/GaN blue light-emitting diodes (LEDs) are needed for future gigabit-per-second visible-light communication systems. Large LED Modulation Bandwidths are typically achieved at high current densities, with reports close to 1 GHz Bandwidth at current densities ranging from 5 to 10 kA/cm2. However, the internal quantum efficiency (IQE) of InGaN/GaN LEDs is quite low at high current densities due to the well-known efficiency droop phenomenon. Here, we show experimentally that nonpolar and semipolar orientations of GaN enable higher Modulation Bandwidths at low current densities where the IQE is expected to be higher and power dissipation is lower. We experimentally compare the Modulation Bandwidth vs. current density for LEDs on nonpolar (101¯0), semipolar (202¯1¯), and polar 0001 orientations. In agreement with wavefunction overlap considerations, the experimental results indicate a higher Modulation Bandwidth for the nonpolar and semipolar LEDs, especially at relatively low current densities....
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Nonpolar GaN-Based Superluminescent Diode with 2.5 GHz Modulation Bandwidth
2018 IEEE International Semiconductor Laser Conference (ISLC), 2018Co-Authors: Ashwin K. Rishinaramangalam, Arman Rashidi, Saadat Mishkat Ul Masabih, Andrew Aragon, Morteza Monavarian, Changmin Lee, Steven P. Denbaars, Daniel F. FeezellAbstract:We report the fabrication and electro-optic characterization of nonpolar GaN-based superluminescent diodes with a tapered waveguide design. The devices were grown and fabricated on freestanding m-plane GaN. An electrical −3dB Modulation Bandwidth of 2.5 GHz is reported at the highest current density.
Levon V. Asryan - One of the best experts on this subject based on the ideXlab platform.
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Modulation Bandwidth of Double Tunneling-Injection Quantum Dot Lasers: Effect of Out-Tunneling Leakage
IEEE Journal of Quantum Electronics, 2019Co-Authors: Levon V. Asryan, Saurav KarAbstract:The effect of out-tunneling leakage of carriers from quantum dots (QDs) on Modulation Bandwidth of semiconductor double tunneling-injection (DTI) QD lasers is studied. In this type of laser, as an alternative to conventional pumping, electrons and holes are injected into QDs by tunneling from two separate quantum wells (QWs) located on the opposite sides of the QD layer and separated from the latter by thin barrier layers. Fast tunneling-injection into QDs should be maintained to ensure the high Modulation Bandwidth. It may also seem that out-tunneling leakage from QDs (tunneling of electrons to the hole-injecting QW and holes to the electron-injecting QW), which is an undesirable process, should be kept as slow as possible (or even totally suppressed) to maximize the Modulation Bandwidth. However, it is shown in this paper that, due to zero-dimensional nature of QDs, the Modulation Bandwidth is practically unaffected by out-tunneling leakage from them—it depends only slightly on the out-tunneling time. Hence, concerning out-tunneling leakage, DTI QD lasers are robust—provided that tunneling-injection is fast, no significant effort should be necessary to suppress out-tunneling leakage in practical devices.
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Modulation Bandwidth of a double tunneling-injection quantum dot laser: The upper limit and limiting factors
2017 IEEE Photonics Society Summer Topical Meeting Series (SUM), 2017Co-Authors: Levon V. AsryanAbstract:The Modulation response in double tunneling-injection quantum dot lasers is analyzed. The highest possible Modulation Bandwidth and the effect of noninstantaneous pumping of quantum dots on the Bandwidth are discussed.
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Modulation Bandwidth of a double tunnelling-injection quantum dot laser
Semiconductor Science and Technology, 2015Co-Authors: Levon V. AsryanAbstract:The Modulation response of a double tunnelling-injection (DTI) quantum dot (QD) laser is studied. Closed-form expressions are obtained for the dynamic characteristics of the laser and the upper limit for the Modulation Bandwidth is estimated. The optimum cavity length, surface density of QDs, and dc injection current density, maximizing the Modulation Bandwidth, are shown to exist. The higher the dc injection current density, the smaller should be the optimum values of the cavity length and the surface density of QDs. While the maximum Bandwidth is shown to be the same in DTI and conventional QD lasers and unaffected by the differential gain, the optimum dc current density, being inversely proportional to the differential gain, is lower in a DTI laser.
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Effect of excited states on the ground-state Modulation Bandwidth in quantum dot lasers
Applied Physics Letters, 2013Co-Authors: Robert A. Suris, Levon V. AsryanAbstract:We consider direct and indirect (excited-state-mediated) capture of carriers from the waveguide region into the lasing ground state in quantum dots (QDs) and calculate the Modulation response of a QD laser. We show that, when only indirect capture is involved, the excited-to-ground-state relaxation delay strongly limits the ground-state Modulation Bandwidth of the laser—at the longest tolerable relaxation time, the Bandwidth becomes zero. When direct capture is also involved, the effect of excited-to-ground-state relaxation is less significant and the Modulation Bandwidth is considerably higher.
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Upper limit for the Modulation Bandwidth of a quantum dot laser
Applied Physics Letters, 2010Co-Authors: Levon V. Asryan, Robert A. SurisAbstract:We derive a closed-form expression for the upper limit for the Modulation Bandwidth of a semiconductor quantum dot (QD) laser. The highest possible Bandwidth increases directly with overlap integral of the electron and hole wave functions in a QD, number of QD-layers, and surface density of QDs in a layer, and is inversely proportional to the inhomogeneous line broadening caused by the QD-size dispersion. At 10% QD-size fluctuations and 100% overlap, the upper limit for the Modulation Bandwidth in a single QD-layer laser can be as high as 60 GHz.
Arman Rashidi - One of the best experts on this subject based on the ideXlab platform.
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high speed nonpolar ingan gan superluminescent diode with 2 5 ghz Modulation Bandwidth
IEEE Photonics Technology Letters, 2020Co-Authors: Arman Rashidi, Ashwin K. Rishinaramangalam, Andrew Aragon, Morteza Monavarian, Changmin Lee, Steven P. Denbaars, Saadat Mishkatulmasabih, Daniel F. FeezellAbstract:We demonstrate a superluminescent diode fabricated on a nonpolar ${m}$ -plane GaN substrate by employing a linearly tapered waveguide design. A high electrical −3dB Modulation Bandwidth ( $f_{\mathbf {3dB}}$ ) of 2.5 GHz at a current density of 30 kA/cm2 is achieved. The high Modulation Bandwidth is attributed to the shorter carrier recombination lifetime, the linear gain curve in the nonpolar ${m}$ -plane quantum wells, and the ability to operate at high current densities while effectively suppressing lasing. We derive a general expression for the −3dB Bandwidth as a function of current density for SLDs using a similar approach to that for laser diodes. The −3dB Bandwidth of a nonpolar superluminescent diode increases exponentially with current density. The experimental results are consistent with the derived expression for $f_{\mathbf {3dB}}$ vs . current density.
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High-Speed Nonpolar InGaN/GaN Superluminescent Diode With 2.5 GHz Modulation Bandwidth
IEEE Photonics Technology Letters, 2020Co-Authors: Arman Rashidi, Ashwin K. Rishinaramangalam, Andrew Aragon, Morteza Monavarian, Changmin Lee, Steven P. Denbaars, Saadat Mishkat-ul-masabih, Daniel F. FeezellAbstract:We demonstrate a superluminescent diode fabricated on a nonpolar ${m}$ -plane GaN substrate by employing a linearly tapered waveguide design. A high electrical −3dB Modulation Bandwidth ( $f_{\mathbf {3dB}}$ ) of 2.5 GHz at a current density of 30 kA/cm2 is achieved. The high Modulation Bandwidth is attributed to the shorter carrier recombination lifetime, the linear gain curve in the nonpolar ${m}$ -plane quantum wells, and the ability to operate at high current densities while effectively suppressing lasing. We derive a general expression for the −3dB Bandwidth as a function of current density for SLDs using a similar approach to that for laser diodes. The −3dB Bandwidth of a nonpolar superluminescent diode increases exponentially with current density. The experimental results are consistent with the derived expression for $f_{\mathbf {3dB}}$ vs . current density.
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Impact of crystal orientation on the Modulation Bandwidth of InGaN/GaN light-emitting diodes
Applied Physics Letters, 2018Co-Authors: Morteza Monavarian, Ashwin K. Rishinaramangalam, Arman Rashidi, Andrew Aragon, Steven P. Denbaars, Daniel F. FeezellAbstract:High-speed InGaN/GaN blue light-emitting diodes (LEDs) are needed for future gigabit-per-second visible-light communication systems. Large LED Modulation Bandwidths are typically achieved at high current densities, with reports close to 1 GHz Bandwidth at current densities ranging from 5 to 10 kA/cm2. However, the internal quantum efficiency (IQE) of InGaN/GaN LEDs is quite low at high current densities due to the well-known efficiency droop phenomenon. Here, we show experimentally that nonpolar and semipolar orientations of GaN enable higher Modulation Bandwidths at low current densities where the IQE is expected to be higher and power dissipation is lower. We experimentally compare the Modulation Bandwidth vs. current density for LEDs on nonpolar (101¯0), semipolar (202¯1¯), and polar 0001 orientations. In agreement with wavefunction overlap considerations, the experimental results indicate a higher Modulation Bandwidth for the nonpolar and semipolar LEDs, especially at relatively low current densities....
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impact of crystal orientation on the Modulation Bandwidth of ingan gan light emitting diodes
Applied Physics Letters, 2018Co-Authors: Morteza Monavarian, Ashwin K. Rishinaramangalam, Arman Rashidi, Andrew Aragon, Steven P. Denbaars, Daniel F. FeezellAbstract:High-speed InGaN/GaN blue light-emitting diodes (LEDs) are needed for future gigabit-per-second visible-light communication systems. Large LED Modulation Bandwidths are typically achieved at high current densities, with reports close to 1 GHz Bandwidth at current densities ranging from 5 to 10 kA/cm2. However, the internal quantum efficiency (IQE) of InGaN/GaN LEDs is quite low at high current densities due to the well-known efficiency droop phenomenon. Here, we show experimentally that nonpolar and semipolar orientations of GaN enable higher Modulation Bandwidths at low current densities where the IQE is expected to be higher and power dissipation is lower. We experimentally compare the Modulation Bandwidth vs. current density for LEDs on nonpolar (101¯0), semipolar (202¯1¯), and polar 0001 orientations. In agreement with wavefunction overlap considerations, the experimental results indicate a higher Modulation Bandwidth for the nonpolar and semipolar LEDs, especially at relatively low current densities....
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Nonpolar GaN-Based Superluminescent Diode with 2.5 GHz Modulation Bandwidth
2018 IEEE International Semiconductor Laser Conference (ISLC), 2018Co-Authors: Ashwin K. Rishinaramangalam, Arman Rashidi, Saadat Mishkat Ul Masabih, Andrew Aragon, Morteza Monavarian, Changmin Lee, Steven P. Denbaars, Daniel F. FeezellAbstract:We report the fabrication and electro-optic characterization of nonpolar GaN-based superluminescent diodes with a tapered waveguide design. The devices were grown and fabricated on freestanding m-plane GaN. An electrical −3dB Modulation Bandwidth of 2.5 GHz is reported at the highest current density.
Kai Wang - One of the best experts on this subject based on the ideXlab platform.
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improving the Modulation Bandwidth of led by cdse zns quantum dots for visible light communication
Optics Express, 2016Co-Authors: Xiangtian Xiao, Haodong Tang, Wanli Chen, Tianqi Zhang, Rui Wang, Wei Chen, Kai WangAbstract:Visible light communication (VLC) is an advanced and high-efficiency wireless communication technology. As one of the most important light sources in VLC, conventional white light emitting diode (WLED) based on Y3Al5O12:Ce3+ (YAG:Ce) phosphor limits the system transmitting rate severely due to its narrow Modulation Bandwidth. Considering the short fluorescent lifetime of quantum dots (QDs), QD-LEDs with wide Modulation Bandwidths were designed here to improve the transmitting rate of VLC. CdSe/ZnS core/shell QDs and related luminescent microspheres (LMS) were implemented as light conversion materials for the QD-LEDs. Compared with conventional phosphor WLED, the proposed QD-LED and QD-WLED reached maximum improvement on Modulation Bandwidth at 74.19% and 67.75% respectively. Furthermore, mathematical modeling of smearing was analyzed to establish the relationship between fluorescent lifetime and Modulation Bandwidth. Our findings will provide an effective solution of white LEDs for high speed VLC.
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Improving the Modulation Bandwidth of LED by CdSe/ZnS quantum dots for visible light communication
Optics express, 2016Co-Authors: Xiangtian Xiao, Haodong Tang, Wanli Chen, Tianqi Zhang, Rui Wang, Wei Chen, Kai WangAbstract:Visible light communication (VLC) is an advanced and high-efficiency wireless communication technology. As one of the most important light sources in VLC, conventional white light emitting diode (WLED) based on Y3Al5O12:Ce3+ (YAG:Ce) phosphor limits the system transmitting rate severely due to its narrow Modulation Bandwidth. Considering the short fluorescent lifetime of quantum dots (QDs), QD-LEDs with wide Modulation Bandwidths were designed here to improve the transmitting rate of VLC. CdSe/ZnS core/shell QDs and related luminescent microspheres (LMS) were implemented as light conversion materials for the QD-LEDs. Compared with conventional phosphor WLED, the proposed QD-LED and QD-WLED reached maximum improvement on Modulation Bandwidth at 74.19% and 67.75% respectively. Furthermore, mathematical modeling of smearing was analyzed to establish the relationship between fluorescent lifetime and Modulation Bandwidth. Our findings will provide an effective solution of white LEDs for high speed VLC.
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Utilizing CdSe/ZnS core/shell QDs to improve the Modulation Bandwidth of WLED for visible light communication
2016 17th International Conference on Electronic Packaging Technology (ICEPT), 2016Co-Authors: Xiangtian Xiao, Haodong Tang, Wanli Chen, Tianqi Zhang, Junjie Hao, Rui Wang, Wei Chen, Kai WangAbstract:Visible light communication (VLC) is an advanced and high-efficiency wireless communication technology. As one of the most important light sources in VLC, conventional white LED based on Y3Al5O12:Ce3+ (YAG:Ce) phosphor limits the system transmitting rate severely due to its narrow Modulation Bandwidth. Considering the short fluorescent lifetime of quantum dots (QDs), QD-LEDs with wide Modulation Bandwidth are designed here to improve the transmitting rate of VLC. CdSe/ZnS core/shell QDs and related luminescent microsphere (LMS) are implemented as light-conversion material for the QD-LEDs. Compared to conventional white LED, the proposed QD-LED reached maximum improvement on Modulation Bandwidth at 74.19%. Our findings will provide an effective solution of white LEDs for high speed VLC.
Morteza Monavarian - One of the best experts on this subject based on the ideXlab platform.
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high speed nonpolar ingan gan superluminescent diode with 2 5 ghz Modulation Bandwidth
IEEE Photonics Technology Letters, 2020Co-Authors: Arman Rashidi, Ashwin K. Rishinaramangalam, Andrew Aragon, Morteza Monavarian, Changmin Lee, Steven P. Denbaars, Saadat Mishkatulmasabih, Daniel F. FeezellAbstract:We demonstrate a superluminescent diode fabricated on a nonpolar ${m}$ -plane GaN substrate by employing a linearly tapered waveguide design. A high electrical −3dB Modulation Bandwidth ( $f_{\mathbf {3dB}}$ ) of 2.5 GHz at a current density of 30 kA/cm2 is achieved. The high Modulation Bandwidth is attributed to the shorter carrier recombination lifetime, the linear gain curve in the nonpolar ${m}$ -plane quantum wells, and the ability to operate at high current densities while effectively suppressing lasing. We derive a general expression for the −3dB Bandwidth as a function of current density for SLDs using a similar approach to that for laser diodes. The −3dB Bandwidth of a nonpolar superluminescent diode increases exponentially with current density. The experimental results are consistent with the derived expression for $f_{\mathbf {3dB}}$ vs . current density.
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High-Speed Nonpolar InGaN/GaN Superluminescent Diode With 2.5 GHz Modulation Bandwidth
IEEE Photonics Technology Letters, 2020Co-Authors: Arman Rashidi, Ashwin K. Rishinaramangalam, Andrew Aragon, Morteza Monavarian, Changmin Lee, Steven P. Denbaars, Saadat Mishkat-ul-masabih, Daniel F. FeezellAbstract:We demonstrate a superluminescent diode fabricated on a nonpolar ${m}$ -plane GaN substrate by employing a linearly tapered waveguide design. A high electrical −3dB Modulation Bandwidth ( $f_{\mathbf {3dB}}$ ) of 2.5 GHz at a current density of 30 kA/cm2 is achieved. The high Modulation Bandwidth is attributed to the shorter carrier recombination lifetime, the linear gain curve in the nonpolar ${m}$ -plane quantum wells, and the ability to operate at high current densities while effectively suppressing lasing. We derive a general expression for the −3dB Bandwidth as a function of current density for SLDs using a similar approach to that for laser diodes. The −3dB Bandwidth of a nonpolar superluminescent diode increases exponentially with current density. The experimental results are consistent with the derived expression for $f_{\mathbf {3dB}}$ vs . current density.
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Impact of crystal orientation on the Modulation Bandwidth of InGaN/GaN light-emitting diodes
Applied Physics Letters, 2018Co-Authors: Morteza Monavarian, Ashwin K. Rishinaramangalam, Arman Rashidi, Andrew Aragon, Steven P. Denbaars, Daniel F. FeezellAbstract:High-speed InGaN/GaN blue light-emitting diodes (LEDs) are needed for future gigabit-per-second visible-light communication systems. Large LED Modulation Bandwidths are typically achieved at high current densities, with reports close to 1 GHz Bandwidth at current densities ranging from 5 to 10 kA/cm2. However, the internal quantum efficiency (IQE) of InGaN/GaN LEDs is quite low at high current densities due to the well-known efficiency droop phenomenon. Here, we show experimentally that nonpolar and semipolar orientations of GaN enable higher Modulation Bandwidths at low current densities where the IQE is expected to be higher and power dissipation is lower. We experimentally compare the Modulation Bandwidth vs. current density for LEDs on nonpolar (101¯0), semipolar (202¯1¯), and polar 0001 orientations. In agreement with wavefunction overlap considerations, the experimental results indicate a higher Modulation Bandwidth for the nonpolar and semipolar LEDs, especially at relatively low current densities....
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impact of crystal orientation on the Modulation Bandwidth of ingan gan light emitting diodes
Applied Physics Letters, 2018Co-Authors: Morteza Monavarian, Ashwin K. Rishinaramangalam, Arman Rashidi, Andrew Aragon, Steven P. Denbaars, Daniel F. FeezellAbstract:High-speed InGaN/GaN blue light-emitting diodes (LEDs) are needed for future gigabit-per-second visible-light communication systems. Large LED Modulation Bandwidths are typically achieved at high current densities, with reports close to 1 GHz Bandwidth at current densities ranging from 5 to 10 kA/cm2. However, the internal quantum efficiency (IQE) of InGaN/GaN LEDs is quite low at high current densities due to the well-known efficiency droop phenomenon. Here, we show experimentally that nonpolar and semipolar orientations of GaN enable higher Modulation Bandwidths at low current densities where the IQE is expected to be higher and power dissipation is lower. We experimentally compare the Modulation Bandwidth vs. current density for LEDs on nonpolar (101¯0), semipolar (202¯1¯), and polar 0001 orientations. In agreement with wavefunction overlap considerations, the experimental results indicate a higher Modulation Bandwidth for the nonpolar and semipolar LEDs, especially at relatively low current densities....
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Nonpolar GaN-Based Superluminescent Diode with 2.5 GHz Modulation Bandwidth
2018 IEEE International Semiconductor Laser Conference (ISLC), 2018Co-Authors: Ashwin K. Rishinaramangalam, Arman Rashidi, Saadat Mishkat Ul Masabih, Andrew Aragon, Morteza Monavarian, Changmin Lee, Steven P. Denbaars, Daniel F. FeezellAbstract:We report the fabrication and electro-optic characterization of nonpolar GaN-based superluminescent diodes with a tapered waveguide design. The devices were grown and fabricated on freestanding m-plane GaN. An electrical −3dB Modulation Bandwidth of 2.5 GHz is reported at the highest current density.