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Manijeh Razeghi - One of the best experts on this subject based on the ideXlab platform.

  • room temperature quantum cascade laser with 31 wall Plug Efficiency
    AIP Advances, 2020
    Co-Authors: Fang Wang, Steven Boyd Slivken, Donghai Wu, Manijeh Razeghi
    Abstract:

    In this article, we report the demonstration of a quantum cascade laser emitting at λ ≈ 4.9 μm with a wall-Plug Efficiency of ∼31% and an output power of ∼23 W in pulsed operation at room temperature with 50 cascade stages (Ns). With proper fabrication and packaging, this buried ridge quantum cascade laser with a cavity length of 5 mm delivers more than ∼15 W output power, and its wall-Plug Efficiency exceeds ∼20% at 100 °C. The experimental results of the lasers are well in agreement with the numerical predictions.

  • room temperature quantum cascade lasers with 22 wall Plug Efficiency in continuous wave operation
    Optics Express, 2020
    Co-Authors: Fang Wang, Steven Boyd Slivken, Donghai Wu, Manijeh Razeghi
    Abstract:

    We report the demonstration of quantum cascade lasers (QCLs) with improved Efficiency emitting at a wavelength of 4.9 µm in pulsed and continuous-wave (CW) operation. Based on an established design and guided by simulation, the number of QCL-emitting stages is increased in order to realize a 29.3% wall Plug Efficiency (WPE) in pulsed operation at room temperature. With proper fabrication and packaging, a 5-mm-long, 8-µm-wide QCL with a buried ridge waveguide is capable of 22% CW WPE and 5.6 W CW output power at room temperature. This corresponds to an extremely high optical density at the output facet of ∼35 MW/cm2, without any damage.

  • Room temperature quantum cascade lasers with 22% wall Plug Efficiency in continuous-wave operation
    Optics Express, 2020
    Co-Authors: Fang Wang, Steven Boyd Slivken, Donghai Wu, Manijeh Razeghi
    Abstract:

    We report the demonstration of quantum cascade lasers (QCLs) with improved Efficiency emitting at a wavelength of 4.9 µm in pulsed and continuous-wave (CW) operation. Based on an established design and guided by simulation, the number of QCL-emitting stages is increased in order to realize a 29.3% wall Plug Efficiency (WPE) in pulsed operation at room temperature. With proper fabrication and packaging, a 5-mm-long, 8-µm-wide QCL with a buried ridge waveguide is capable of 22% CW WPE and 5.6 W CW output power at room temperature. This corresponds to an extremely high optical density at the output facet of ∼35 MW/cm2, without any damage.

  • continuous wave quantum cascade lasers with 5 6 w output power at room temperature and 41 wall Plug Efficiency in cryogenic operation
    AIP Advances, 2020
    Co-Authors: Fang Wang, Steven Boyd Slivken, Donghai Wu, Quanyong Lu, Manijeh Razeghi
    Abstract:

    In this paper, we report a post-polishing technique to achieve nearly complete surface planarization for the buried ridge regrowth processing of quantum cascade lasers. The planarized device geometry improves the thermal conduction and reliability and, most importantly, enhances the power and Efficiency in continuous wave operation. With this technique, we demonstrate a high continuous wave wall-Plug Efficiency of an InP-based quantum cascade laser reaching ∼41% with an output power of ∼12 W from a single facet operating at liquid nitrogen temperature. At room temperature, the continuous wave output power exceeds the previous record, reaching ∼5.6 W.

  • Continuous wave quantum cascade lasers with 5.6 W output power at room temperature and 41% wall-Plug Efficiency in cryogenic operation
    AIP Advances, 2020
    Co-Authors: Fang Wang, Steven Boyd Slivken, Donghai Wu, Quanyong Lu, Manijeh Razeghi
    Abstract:

    In this paper, we report a post-polishing technique to achieve nearly complete surface planarization for the buried ridge regrowth processing of quantum cascade lasers. The planarized device geometry improves the thermal conduction and reliability and, most importantly, enhances the power and Efficiency in continuous wave operation. With this technique, we demonstrate a high continuous wave wall-Plug Efficiency of an InP-based quantum cascade laser reaching ∼41% with an output power of ∼12 W from a single facet operating at liquid nitrogen temperature. At room temperature, the continuous wave output power exceeds the previous record, reaching ∼5.6 W.

Steven Boyd Slivken - One of the best experts on this subject based on the ideXlab platform.

  • room temperature quantum cascade laser with 31 wall Plug Efficiency
    AIP Advances, 2020
    Co-Authors: Fang Wang, Steven Boyd Slivken, Donghai Wu, Manijeh Razeghi
    Abstract:

    In this article, we report the demonstration of a quantum cascade laser emitting at λ ≈ 4.9 μm with a wall-Plug Efficiency of ∼31% and an output power of ∼23 W in pulsed operation at room temperature with 50 cascade stages (Ns). With proper fabrication and packaging, this buried ridge quantum cascade laser with a cavity length of 5 mm delivers more than ∼15 W output power, and its wall-Plug Efficiency exceeds ∼20% at 100 °C. The experimental results of the lasers are well in agreement with the numerical predictions.

  • room temperature quantum cascade lasers with 22 wall Plug Efficiency in continuous wave operation
    Optics Express, 2020
    Co-Authors: Fang Wang, Steven Boyd Slivken, Donghai Wu, Manijeh Razeghi
    Abstract:

    We report the demonstration of quantum cascade lasers (QCLs) with improved Efficiency emitting at a wavelength of 4.9 µm in pulsed and continuous-wave (CW) operation. Based on an established design and guided by simulation, the number of QCL-emitting stages is increased in order to realize a 29.3% wall Plug Efficiency (WPE) in pulsed operation at room temperature. With proper fabrication and packaging, a 5-mm-long, 8-µm-wide QCL with a buried ridge waveguide is capable of 22% CW WPE and 5.6 W CW output power at room temperature. This corresponds to an extremely high optical density at the output facet of ∼35 MW/cm2, without any damage.

  • Room temperature quantum cascade lasers with 22% wall Plug Efficiency in continuous-wave operation
    Optics Express, 2020
    Co-Authors: Fang Wang, Steven Boyd Slivken, Donghai Wu, Manijeh Razeghi
    Abstract:

    We report the demonstration of quantum cascade lasers (QCLs) with improved Efficiency emitting at a wavelength of 4.9 µm in pulsed and continuous-wave (CW) operation. Based on an established design and guided by simulation, the number of QCL-emitting stages is increased in order to realize a 29.3% wall Plug Efficiency (WPE) in pulsed operation at room temperature. With proper fabrication and packaging, a 5-mm-long, 8-µm-wide QCL with a buried ridge waveguide is capable of 22% CW WPE and 5.6 W CW output power at room temperature. This corresponds to an extremely high optical density at the output facet of ∼35 MW/cm2, without any damage.

  • continuous wave quantum cascade lasers with 5 6 w output power at room temperature and 41 wall Plug Efficiency in cryogenic operation
    AIP Advances, 2020
    Co-Authors: Fang Wang, Steven Boyd Slivken, Donghai Wu, Quanyong Lu, Manijeh Razeghi
    Abstract:

    In this paper, we report a post-polishing technique to achieve nearly complete surface planarization for the buried ridge regrowth processing of quantum cascade lasers. The planarized device geometry improves the thermal conduction and reliability and, most importantly, enhances the power and Efficiency in continuous wave operation. With this technique, we demonstrate a high continuous wave wall-Plug Efficiency of an InP-based quantum cascade laser reaching ∼41% with an output power of ∼12 W from a single facet operating at liquid nitrogen temperature. At room temperature, the continuous wave output power exceeds the previous record, reaching ∼5.6 W.

  • Continuous wave quantum cascade lasers with 5.6 W output power at room temperature and 41% wall-Plug Efficiency in cryogenic operation
    AIP Advances, 2020
    Co-Authors: Fang Wang, Steven Boyd Slivken, Donghai Wu, Quanyong Lu, Manijeh Razeghi
    Abstract:

    In this paper, we report a post-polishing technique to achieve nearly complete surface planarization for the buried ridge regrowth processing of quantum cascade lasers. The planarized device geometry improves the thermal conduction and reliability and, most importantly, enhances the power and Efficiency in continuous wave operation. With this technique, we demonstrate a high continuous wave wall-Plug Efficiency of an InP-based quantum cascade laser reaching ∼41% with an output power of ∼12 W from a single facet operating at liquid nitrogen temperature. At room temperature, the continuous wave output power exceeds the previous record, reaching ∼5.6 W.

Guoqiang Li - One of the best experts on this subject based on the ideXlab platform.

  • 395 nm gan based near ultraviolet light emitting diodes on si substrates with a high wall Plug Efficiency of 52 0 350 ma
    Optics Express, 2019
    Co-Authors: Yuan Li, Wenliang Wang, Yulin Zheng, Xin Tang, Deqi Kong, Runze Li, Xiaobin He, Guoqiang Li
    Abstract:

    : The high-performance 395 nm GaN-based near-ultraviolet (UV) light emitting diodes (LEDs) on Si substrates have been obtained by designing an AlN buffer layer to decrease the dislocations density of the GaN layer. By adopting a multi-layer structure with a high- and low-V/III ratio alternation, a high-quality AlN buffer layer has been obtained with a small full-width at half-maximum (FWHM) for AlN(0002) X-ray rocking curve (XRC) of 648 arcsec and a small root-mean-square roughness of 0.11 nm. By applying the optimized AlN buffer layer, the high-quality GaN layer with GaN(0002) and GaN(10-12) XRC FWHM of 260 and 270 arcsec have been obtained, and the high-performance GaN-based near-UV LED wafers and chips have been fabricated accordingly. The as-fabricated near-UV LED chips exhibit a light output power of 550 mW with a forward voltage of 3.02 V at 350 mA, corresponding to a wall-Plug Efficiency of 52.0%. These chips with outstanding performance are of paramount importance in the application of curing, sterilization, efficient white lighting, etc.

  • Impact of Silver Surface Morphology on the Wall Plug Efficiency of Blue Vertical Light-Emitting Diodes
    IEEE Transactions on Electron Devices, 2019
    Co-Authors: Zichen Zhang, Yunpeng Zhang, Guoqiang Li
    Abstract:

    Due to merits of good thermal conductivity and vertical current distribution, vertical light-emitting diodes (VLEDs) have been widely studied for many years. However, the wall Plug Efficiency (WPE) remains limited by the light trapping effect in GaN cavity and difficulties to achieve low-resistance ohmic contacts to p-GaN. As one of the solutions, Ni-/Ag-based mirror layers as ohmic contacts have attracted much attention due to the high work function of Ni and high reflectivity of Ag for blue light. In this paper, a Ni/Ag/Ni/Ag/Ti metal stack was deposited separately on the surface of p-GaN. A high WPE of 45.7% for GaN-based blue VLEDs on Si substrates has been achieved at the mean diameter (69 nm) of Ag grains and root-mean-square (rms) surface roughness (2.06 nm) of Ag mirror layers. There are three impacts on VF: formation of NiO, growth of Ag grain, and increases of Ag oxide. The impacts of surface topography on optical properties are investigated by the Mie scattering theory for Ag grains and surface scattering theory for roughness surface of Ag mirror layer. The conclusion shows that: 1) with growth of Ag grain, the absorption of Ag grains is heightened obviously and the intensity distribution of scattering light with scattering angle is changed from uniformity to irregularity and 2) since the magnitudes of specular reflectance are dramatically larger than the scattering about 1011 times, the specular reflectance of Ag roughness surface totally covers the attribution of scattering and is only decided by rms values and wavelength of incident light.

L A Coldren - One of the best experts on this subject based on the ideXlab platform.

  • high wall Plug Efficiency temperature insensitive vertical cavity surface emitting lasers with low barrier p type mirrors
    Vertical-Cavity Surface-Emitting Laser Arrays, 1994
    Co-Authors: M G Peters, Bruce D Young, Frank H Peters, B J Thibeault, J W Scott, S W Corzine, Robert W Herrick, L A Coldren
    Abstract:

    Vertical-cavity surface-emitting lasers (VCSELs) are promising candidates as efficient sources for optical fiber communication due to their high Efficiency coupling to fibers, single longitudinal mode operation, and ability to be integrated as arrays on a single chip. The best overall measurement of practical device performance is the wall-Plug Efficiency, defined as total optical power out divided by total electrical power in. The theoretical mechanisms that effect the wall-Plug Efficiency of VCSELs will be analyzed and discussed, especially the trade- off between differential Efficiency and threshold current. Experimentally, modifications of the growth structure which improve wall-Plug Efficiency have been implemented. The drive voltage has been reduced and the optical loss is also decreased by using lower barrier p-type Al0.67Ga0.33As/GaAs mirrors with special interface gradings. Also, by offsetting the quantum- well gain peak from the cavity mode, the gain overlap is optimized at the true active-region operating temperature (above room-temperature). These effects combine to yield a peak CW room- temperature wall-Plug Efficiency of 17.3%.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

  • 17.3% peak wall Plug Efficiency vertical-cavity surface-emitting lasers using lower barrier mirrors
    IEEE Photonics Technology Letters, 1994
    Co-Authors: M G Peters, Frank H Peters, B J Thibeault, J W Scott, D.b. Young, L A Coldren
    Abstract:

    Modifications to the epitaxial growth of vertical-cavity surface-emitting laser (VCSEL) material have recently led to improved characteristics. By offsetting the quantum-well gain peak from the cavity mode, and implementing lower barrier p-type Al/sub 0.67/Ga/sub 0.33/As/GaAs DBR mirrors with parabolic interface gradings, better high-temperature operation and lower voltages have been achieved. These effects combine to yield a peak wall Plug Efficiency of 17.3% for room temperature, CW operation.

Miriam S Vitiello - One of the best experts on this subject based on the ideXlab platform.

  • microprobe photoluminescence assessment of the wall Plug Efficiency in interband cascade lasers
    Journal of Applied Physics, 2008
    Co-Authors: Miriam S Vitiello, Gaetano Scamarcio, Vincenzo Spagnolo, William W Bewley, I Vurgaftman, J R Meyer, Antonia Lops
    Abstract:

    We employ a microprobe photoluminescence (PL) technique to determine the thermal resistance and wall-Plug Efficiency of narrow-ridge interband cascade lasers emitting at 3.8 μm. Using two different semiconductor epilayers as integrated thermometers, the local lattice temperature is extracted from the PL spectra and the wall-Plug Efficiency (ηw) derived from the slope of the temperature increase versus electrical power. The maximum ηw at 78 K is found to be 8.1±0.5%, and a fit to the lattice temperature gradient implies cross-plane thermal conductivities of 4.5–6.5 W/m K for the short-period InAs/AlSb superlattice cladding and of ≈1.5–4 W/m K for the active region.

  • Experimental measurement of the wall-Plug Efficiency in THz quantum cascade lasers
    2007 Conference on Lasers and Electro-Optics (CLEO), 2007
    Co-Authors: Miriam S Vitiello, Gaetano Scamarcio, Vincenzo Spagnolo
    Abstract:

    The wall-Plug Efficiency and the thermal resistance of bound-to-continuum THz quantum-cascade lasers are extracted from the analysis of micro-probe photoluminescence spectra, via the direct measurement of the lattice temperature as a function of the electrical-power.

  • terahertz quantum cascade lasers with large wall Plug Efficiency
    Applied Physics Letters, 2007
    Co-Authors: Miriam S Vitiello, Gaetano Scamarcio, Vincenzo Spagnolo, S S Dhillon, Carlo Sirtori
    Abstract:

    Improved optical power performance of bound-to-continuum quantum-cascade lasers operating at 2.83THz is reported. Peak optical powers of 100mW at 4K and power conversion-efficiencies as high as ηw=(5.5±0.4)% in continuous wave at 40K were measured. The ηw values were assessed via an experimental method based on the analysis of the local lattice temperature as extracted by microprobe photoluminescence versus electrical power. From the measured ηw values they extracted a slope Efficiency value 0.41±0.11W∕A.