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Shuji Nakamura - One of the best experts on this subject based on the ideXlab platform.

  • efficient tunnel junction contacts for high power semipolar iii nitride edge Emitting Laser diodes
    Optics Express, 2019
    Co-Authors: Kareem W Hamdy, Erin C Young, Steven P Denbaars, James S Speck, Abdullah I Alhassan, Daniel L Becerra, Shuji Nakamura
    Abstract:

    We demonstrate high-power edge-Emitting Laser diodes (LDs) with tunnel junction contacts grown by molecular beam epitaxy (MBE). Under pulsed conditions, lower threshold current densities were observed from LDs with MBE-grown tunnel junctions than from similarly fabricated control LDs with ITO contacts. LDs with tunnel junction contacts grown by metal-organic chemical vapor deposition (MOCVD) were additionally demonstrated. These LDs were fabricated using a p-GaN activation scheme utilizing lateral diffusion of hydrogen through the LD ridge sidewalls. Secondary ion mass spectroscopy measurements of the [Si] and [Mg] profiles in the MBE-grown and MOCVD-grown tunnel junctions were conducted to further investigate the results.

  • efficient tunnel junction contacts for high power semipolar iii nitride edge Emitting Laser diodes
    Optics Express, 2019
    Co-Authors: Kareem W Hamdy, Erin C Young, Steven P Denbaars, James S Speck, Abdullah I Alhassan, Daniel L Becerra, Shuji Nakamura
    Abstract:

    We demonstrate high-power edge-Emitting Laser diodes (LDs) with tunnel junction contacts grown by molecular beam epitaxy (MBE). Under pulsed conditions, lower threshold current densities were observed from LDs with MBE-grown tunnel junctions than from similarly fabricated control LDs with ITO contacts. LDs with tunnel junction contacts grown by metal-organic chemical vapor deposition (MOCVD) were additionally demonstrated. These LDs were fabricated using a p-GaN activation scheme utilizing lateral diffusion of hydrogen through the LD ridge sidewalls. Secondary ion mass spectroscopy measurements of the [Si] and [Mg] profiles in the MBE-grown and MOCVD-grown tunnel junctions were conducted to further investigate the results.

  • demonstration of a iii nitride edge Emitting Laser diode utilizing a gan tunnel junction contact
    Optics Express, 2016
    Co-Authors: Benjamin P Yonkee, Erin C Young, Steven P Denbaars, James S Speck, Changmin Lee, John T Leonard, Shuji Nakamura
    Abstract:

    We demonstrate a III-nitride edge Emitting Laser diode (EELD) grown on a (2021) bulk GaN substrate with a GaN tunnel junction contact for hole injection. The tunnel junction was grown using a combination of metal-organic chemical-vapor deposition (MOCVD) and ammonia-based molecular-beam epitaxy (MBE) which allowed to be regrown over activated p-GaN. For a Laser bar with dimensions of 1800 µm x 2.5 µm, without facet coatings, the threshold current was 284 mA (6.3 kA/cm2) and the single facet slope efficiency was 0.33 W/A (12% differential efficiency). A differential resistivity at high current density of 2.3 × 10-4 Ω cm2 was measured.

  • nonpolar iii nitride vertical cavity surface Emitting Laser with a photoelectrochemically etched air gap aperture
    Applied Physics Letters, 2016
    Co-Authors: John T Leonard, Benjamin P Yonkee, Steven P Denbaars, James S Speck, Daniel A Cohen, Ludovico Megalini, Shuji Nakamura
    Abstract:

    We demonstrate a III-nitride nonpolar vertical-cavity surface-Emitting Laser (VCSEL) with a photoelectrochemically (PEC) etched aperture. The PEC lateral undercut etch is used to selectively remove the multi-quantum well (MQW) region outside the aperture area, defined by an opaque metal mask. This PEC aperture (PECA) creates an air-gap in the passive area of the device, allowing one to achieve efficient electrical confinement within the aperture, while simultaneously achieving a large index contrast between core of the device (the MQW within the aperture) and the lateral cladding of the device (the air-gap formed by the PEC etch), leading to strong lateral confinement. Scanning electron microscopy and focused ion-beam analysis is used to investigate the precision of the PEC etch technique in defining the aperture. The fabricated single mode PECA VCSEL shows a threshold current density of ∼22 kA/cm2 (25 mA), with a peak output power of ∼180 μW, at an emission wavelength of 417 nm. The near-field emission p...

Kent D Choquette - One of the best experts on this subject based on the ideXlab platform.

  • single mode 1 3 spl mu m photonic crystal vertical cavity surface Emitting Laser
    IEEE Photonics Technology Letters, 2006
    Co-Authors: Paul O Leisher, Aaron J Danner, Kent D Choquette
    Abstract:

    We report the use of a photonic crystal in a 1.3-mum vertical-cavity surface-Emitting Laser to achieve single fundamental-mode operation. A focused ion beam was used to mill the photonic crystal into a top dielectric distributed Bragg reflector. The Laser operated continuous-wave at room temperature with greater than 1 mW of single-mode output power observed with a sidemode suppression ratio of more than 37 dB and little change to the electrical properties of the device

  • vertical cavity surface Emitting Laser operating with photonic crystal seven point defect structure
    Applied Physics Letters, 2003
    Co-Authors: Noriyuki Yokouchi, Aaron J Danner, Kent D Choquette
    Abstract:

    A vertical-cavity surface-Emitting Laser with a two-dimensional photonic crystal (PC) structure has been investigated for single lateral mode operation. The PC confined mode can be controlled by the lattice constant, the hole diameter, the etching depth, and the defect structure. A seven-point defect structure is proposed to enhance the confinement effect, which is diluted by finite hole depth of the PC structure. We obtained a pure PC confined mode under room-temperature cw conditions with a PC lattice constant of 2 μm, hole diameters of 1.0 and 1.4 μm, and depths of 1.85 and 1.92 μm, respectively.

  • etching depth dependence of the effective refractive index in two dimensional photonic crystal patterned vertical cavity surface Emitting Laser structures
    Applied Physics Letters, 2003
    Co-Authors: Noriyuki Yokouchi, Aaron J Danner, Kent D Choquette
    Abstract:

    A vertical-cavity surface-Emitting Laser (VCSEL) having a two-dimensional (2-D) photonic crystal structure on its surface has been investigated for single-lateral-mode operation. We evaluated the effective index change of a VCSEL cavity introduced by a 2-D pattern. Our experimental results showed good agreement with a theoretical model in which the influence of a finite etching depth was taken into consideration. The etching-depth dependence parameter γ, which can be explained by the optical power distribution inside a VCSEL structure, will be helpful for controlling the lateral mode of VCSEL devices.

  • modal analysis of a small surface Emitting Laser with a selectively oxidized waveguide
    Applied Physics Letters, 1995
    Co-Authors: K L Lear, Kent D Choquette, R P Schneider, S P Kilcoyne
    Abstract:

    We describe studies of an index‐guided ∼4×3 μm2 vertical cavity surface Emitting Laser with a cw, room temperature 133 μA threshold current and 53% slope efficiency fabricated using selective wet thermal oxidation to provide optical and electrical confinement. While the device operates strictly single mode, a large number of transverse modes are evident in the subthreshold luminescence observed in both vertical and lateral directions. Despite the lumped nature of the index region, the transverse mode wavelengths agree very well with those predicted for a conventional distributed waveguide structure. Waveguide dimensions and an effective index step of 2% between the active and cladding region are determined by fitting the modal data.

  • vertical cavity surface Emitting Laser diodes fabricated by in situ dry etching and molecular beam epitaxial regrowth
    IEEE Photonics Technology Letters, 1993
    Co-Authors: Kent D Choquette, M Hong, Robert S Freund, J P Mannaerts, Robert C Wetzel, R E Leibenguth
    Abstract:

    The authors report the first buried active region vertical-cavity surface-Emitting Laser diodes fabricated using in situ dry etching and molecular beam epitaxial regrowth. The Laser emissions of the etched/regrown devices persist over a greater current range and exhibit maximum output powers larger than air-post Lasers. The Lasers are anisotropically etched into the lower monolithic distributed Bragg reflector using an electron cyclotron resonance SiCl/sub 4/ plasma etch. After transfer in ultra-high vacuum, epitaxial AlGaAs current blocking layers are regrown around the etched mesas. Polycrystalline deposition on the SiO/sub 2/ mask is removed by reactive ion etching to allow electrical contact and top surface emission. The etched/regrown Laser characteristics demonstrate efficient current confinement and low thermal impedance. The vacuum integrated processing described offers the prospect of further device performance enhancements and greater functionality. >

Wanhua Zheng - One of the best experts on this subject based on the ideXlab platform.

  • Lateral Cavity Photonic Crystal Surface Emitting Laser With Narrow Divergence Angle
    IEEE Photonics Technology Letters, 2016
    Co-Authors: Yufei Wang, Aiyi Qi, Fan Qi, Siriguleng Zhang, Wanhua Zheng
    Abstract:

    We demonstrate an electrical injection lateral cavity photonic crystal surface Emitting Laser (LC-PCSEL) with a narrow divergence angle of less than 4.8° and nearly circular beam at communication wavelength. Different etching depth of PC air hole results in varied divergence angle for both PC element and PC array structure. Shallow-etching PC array structure has a great advantage in achieving a narrow divergence angle, nearly circular beam, high far-field intensity, and large fabrication tolerance. By rotating the device from 0° to 180°, the measured divergence angles are less than 4.8°. Therefore, a narrow divergence angle LC-PCSEL with circular beam is achieved due to six-fold rotational symmetry. This is a demonstration of the 2-D coherent oscillations, which reflects the nature of 2-D PC. Our demonstration promises to realize extensive applications in on-chip communication, and interconnects for surface Emitting Laser in communication wavelength.

  • lateral cavity photonic crystal surface Emitting Laser with ultralow threshold
    Optics Letters, 2011
    Co-Authors: Wanhua Zheng, Wei Chen, Wenjun Zhou, Yufei Wang, Anjin Liu, Hailing Wang
    Abstract:

    A lateral cavity photonic crystal (PhC) surface-Emitting Laser is realized on a commercial epitaxial waveguide wafer without a distributed Bragg reflector first. Energy is coupled from the lateral resonance to surface-Emitting light through the Γ band edge of the PhC with a square lattice. Electrically driven 1553.8 nm surface-Emitting lasing action is observed at room temperature. The threshold current density of 667 A/cm2 is ultralow for the surface-Emitting Laser.

  • novel lateral cavity surface Emitting Laser on commercial epitaxial waveguide wafer without dbr layers
    Conference on Lasers and Electro-Optics, 2011
    Co-Authors: Wenjun Zhou, Wei Chen, Anjin Liu, Hailing Wang, Yu Wang, Wanhua Zheng
    Abstract:

    Novel lateral cavity surface Emitting Laser was realized on the commercial epitaxial wafer based on the photonic crystal band edge mode lateral resonance. Electrically driven single mode lasing action was obtained at room temperature.

  • reduced divergence angle of photonic crystal vertical cavity surface Emitting Laser
    Applied Physics Letters, 2009
    Co-Authors: Mingxin Xing, Hongwei Qu, Wei Chen, Wenjun Zhou, Wanhua Zheng
    Abstract:

    The reduced divergence angle of the photonic crystal vertical-cavity surface-Emitting Laser (PC-VCSEL) was investigated in both theory and experiment. The photonic crystal waveguide possessed the weakly guiding waveguide characteristic, which accounted for the reduction of the divergence angle. The three-dimensional finite-difference time-domain method was used to simulate the designed PC-VCSEL, and a calculated divergence angle of 5.2° was obtained. The measured divergence angles of our fabricated PC-VCSEL were between 5.1° and 5.5° over the entire drive current range, consistent with the numerical results. This is the lowest divergence angle of the fabricated PC-VCSEL ever reported.

Shingchung Wang - One of the best experts on this subject based on the ideXlab platform.

  • cw lasing of current injection blue gan based vertical cavity surface Emitting Laser
    Applied Physics Letters, 2008
    Co-Authors: Chih Chiang Kao, Haochung Kuo, Gen Sheng Huang, Shingchung Wang
    Abstract:

    Here, we report the cw Laser operation of electrically pumped GaN-based vertical cavity surface Emitting Laser (VCSEL). The GaN-based VCSEL has a ten-pair InGaN∕GaN multiple quantum well active layer embedded in a GaN hybrid microcavity of 5λ optical thickness with two high reflectivity mirrors provided by an epitaxially grown AlN∕GaN distributed Bragg reflector (DBR) and a Ta2O5∕SiO2 dielectric DBR. cw Laser action was achieved at a threshold injection current of 1.4mA at 77K. The Laser emitted a blue wavelength at 462nm with a narrow linewidth of about 0.15nm. The Laser beam has a divergence angle of about 11.7° with a polarization ratio of 80%. A very strong spontaneous coupling efficiency of 7.5×10−2 was measured.

  • fabrication and performance of blue gan based vertical cavity surface Emitting Laser employing aln gan and ta2o5 sio2 distributed bragg reflector
    Applied Physics Letters, 2005
    Co-Authors: Yuyun Peng, J Y Tsai, Yunghuang Chang, Hungwen Huang, Tienchang Lu, Shingchung Wang
    Abstract:

    GaN-based vertical-cavity surface Emitting Laser with 3 λ cavity and hybrid mirrors, consisting of the 25 pairs AlN∕GaN dielectric Bragg reflector and the 8 pairs Ta2O5∕SiO2, was fabricated. The Laser action was achieved under the optical pumping at room temperature with a threshold pumping energy density of about 53mJ∕cm2. The Laser emits 448 nm blue wavelength with a linewidth of 0.25 nm and the Laser beam has a degree of polarization of about 84%.

Steven P Denbaars - One of the best experts on this subject based on the ideXlab platform.

  • efficient tunnel junction contacts for high power semipolar iii nitride edge Emitting Laser diodes
    Optics Express, 2019
    Co-Authors: Kareem W Hamdy, Erin C Young, Steven P Denbaars, James S Speck, Abdullah I Alhassan, Daniel L Becerra, Shuji Nakamura
    Abstract:

    We demonstrate high-power edge-Emitting Laser diodes (LDs) with tunnel junction contacts grown by molecular beam epitaxy (MBE). Under pulsed conditions, lower threshold current densities were observed from LDs with MBE-grown tunnel junctions than from similarly fabricated control LDs with ITO contacts. LDs with tunnel junction contacts grown by metal-organic chemical vapor deposition (MOCVD) were additionally demonstrated. These LDs were fabricated using a p-GaN activation scheme utilizing lateral diffusion of hydrogen through the LD ridge sidewalls. Secondary ion mass spectroscopy measurements of the [Si] and [Mg] profiles in the MBE-grown and MOCVD-grown tunnel junctions were conducted to further investigate the results.

  • efficient tunnel junction contacts for high power semipolar iii nitride edge Emitting Laser diodes
    Optics Express, 2019
    Co-Authors: Kareem W Hamdy, Erin C Young, Steven P Denbaars, James S Speck, Abdullah I Alhassan, Daniel L Becerra, Shuji Nakamura
    Abstract:

    We demonstrate high-power edge-Emitting Laser diodes (LDs) with tunnel junction contacts grown by molecular beam epitaxy (MBE). Under pulsed conditions, lower threshold current densities were observed from LDs with MBE-grown tunnel junctions than from similarly fabricated control LDs with ITO contacts. LDs with tunnel junction contacts grown by metal-organic chemical vapor deposition (MOCVD) were additionally demonstrated. These LDs were fabricated using a p-GaN activation scheme utilizing lateral diffusion of hydrogen through the LD ridge sidewalls. Secondary ion mass spectroscopy measurements of the [Si] and [Mg] profiles in the MBE-grown and MOCVD-grown tunnel junctions were conducted to further investigate the results.

  • demonstration of a iii nitride edge Emitting Laser diode utilizing a gan tunnel junction contact
    Optics Express, 2016
    Co-Authors: Benjamin P Yonkee, Erin C Young, Steven P Denbaars, James S Speck, Changmin Lee, John T Leonard, Shuji Nakamura
    Abstract:

    We demonstrate a III-nitride edge Emitting Laser diode (EELD) grown on a (2021) bulk GaN substrate with a GaN tunnel junction contact for hole injection. The tunnel junction was grown using a combination of metal-organic chemical-vapor deposition (MOCVD) and ammonia-based molecular-beam epitaxy (MBE) which allowed to be regrown over activated p-GaN. For a Laser bar with dimensions of 1800 µm x 2.5 µm, without facet coatings, the threshold current was 284 mA (6.3 kA/cm2) and the single facet slope efficiency was 0.33 W/A (12% differential efficiency). A differential resistivity at high current density of 2.3 × 10-4 Ω cm2 was measured.

  • nonpolar iii nitride vertical cavity surface Emitting Laser with a photoelectrochemically etched air gap aperture
    Applied Physics Letters, 2016
    Co-Authors: John T Leonard, Benjamin P Yonkee, Steven P Denbaars, James S Speck, Daniel A Cohen, Ludovico Megalini, Shuji Nakamura
    Abstract:

    We demonstrate a III-nitride nonpolar vertical-cavity surface-Emitting Laser (VCSEL) with a photoelectrochemically (PEC) etched aperture. The PEC lateral undercut etch is used to selectively remove the multi-quantum well (MQW) region outside the aperture area, defined by an opaque metal mask. This PEC aperture (PECA) creates an air-gap in the passive area of the device, allowing one to achieve efficient electrical confinement within the aperture, while simultaneously achieving a large index contrast between core of the device (the MQW within the aperture) and the lateral cladding of the device (the air-gap formed by the PEC etch), leading to strong lateral confinement. Scanning electron microscopy and focused ion-beam analysis is used to investigate the precision of the PEC etch technique in defining the aperture. The fabricated single mode PECA VCSEL shows a threshold current density of ∼22 kA/cm2 (25 mA), with a peak output power of ∼180 μW, at an emission wavelength of 417 nm. The near-field emission p...