Fabrication and performance of selectively oxidized vertical-cavity lasers
TL;DR: In this article, the authors report the high yield fabrication and reproducible performance of selectively oxidized vertical-cavity surface emitting lasers. Butler et al. showed that linear oxidation rates of AlGaAs without an induction period allows reproducible fabrication of buried oxide current apertures within monolithic distributed Bragg reflectors.
Abstract: We report the high yield fabrication and reproducible performance of selectively oxidized vertical-cavity surface emitting lasers. We show that linear oxidation rates of AlGaAs without an induction period allows reproducible fabrication of buried oxide current apertures within monolithic distributed Bragg reflectors. The oxide layers do not induce obvious crystalline defects, and continuous wave operation in excess of 650 h has been obtained. The high yield fabrication enables relatively high laser performance over a wide wavelength span. We observe submilliamp threshold currents over a wavelength range of up to 75 nm, and power conversion efficiencies at 1 mW output power of greater than 20% over a 50-nm wavelength range. >
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TL;DR: In this paper, the authors describe the design, fabrication, and measured characteristics of the high-power optically pumped-semiconductor (OPS) vertical-external-cavity surface-emitting lasers (VCSELs).
Abstract: We describe the design, fabrication, and measured characteristics of the high-power optically pumped-semiconductor (OPS) vertical-external-cavity surface-emitting lasers (VCSELs). Using diode laser pumping, we have recently demonstrated operation of such lasers, which for the first time generate high (watt-level) power and a circular Gaussian beam directly from a semiconductor laser. These OPS-VECSELs have a strain-compensated multi-quantum-well InGaAs-GaAsP-GaAs structure and operate CW near /spl lambda//spl sim/1004 nm with output power of 0.69 W in TEM/sub 11/ mode, 0.52 W in TEM/sub 00/ mode and 0.37 W coupled to a single-mode fiber. With multiple pump and gain elements, OPS-VCSEL technology is scalable to the multiwatt power levels. Such lasers will prove useful in a variety of applications requiring compact and efficient sources with high-power output in a single-mode fiber or with diffraction-limited beam quality.
389 citations
Cites background from "Fabrication and performance of sele..."
...OPS VECSEL’s: OPS VECSEL’s combine the approaches of diode-pumped solid-state lasers [2], [3], and semiconductor QW VCSEL lasers [4], [ 12 ]‐[17], drawing on the advantages of both....
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...For small device diameters ( 10 m), VCSEL’s operate in a single transverse mode with output power limited to less than about 10 mW [ 12 ], [14]....
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...SEL’s) [4], [ 12 ]‐[16] have the desired circular output beams....
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TL;DR: The polarization properties of the SHG reveal that both bulk and surface nonlinearities play important roles in the observed nonlinear process, and this work presents, for the first time, resonantly enhanced second-harmonic generation using gallium arsenide (GaAs) based dielectric metasurfaces.
Abstract: Nonlinear optical phenomena in nanostructured materials have been challenging our perceptions of nonlinear optical processes that have been explored since the invention of lasers. For example, the ability to control optical field confinement, enhancement, and scattering almost independently allows nonlinear frequency conversion efficiencies to be enhanced by many orders of magnitude compared to bulk materials. Also, the subwavelength length scale renders phase matching issues irrelevant. Compared with plasmonic nanostructures, dielectric resonator metamaterials show great promise for enhanced nonlinear optical processes due to their larger mode volumes. Here, we present, for the first time, resonantly enhanced second-harmonic generation (SHG) using gallium arsenide (GaAs) based dielectric metasurfaces. Using arrays of cylindrical resonators we observe SHG enhancement factors as large as 10(4) relative to unpatterned GaAs. At the magnetic dipole resonance, we measure an absolute nonlinear conversion efficiency of ∼2 × 10(-5) with ∼3.4 GW/cm(2) pump intensity. The polarization properties of the SHG reveal that both bulk and surface nonlinearities play important roles in the observed nonlinear process.
384 citations
TL;DR: In this article, the chemistry, microstructure, and processing of buried oxides converted from AlGaAs layers using wet oxidation was reviewed and the influence of gas flow, gas composition, temperature, Al-content, and layer thickness on the oxidation rate was characterized.
Abstract: We review the chemistry, microstructure, and processing of buried oxides converted from AlGaAs layers using wet oxidation Hydrogen is shown to have a central role in the oxidation reaction as the oxidizing agent and to reduce the intermediate predict As/sub 2/O/sub 3/ to As The stable oxide is amorphous (Al/sub x/Ga/sub 1-x/)/sub 2/O/sub 3/ which has no defects along the oxide/semiconductor interfaces but can exhibit strain at the oxide terminus due to volume shrinkage The influence of gas flow, gas composition, temperature, Al-content, and layer thickness on the oxidation rate are characterized to establish a reproducible process Linear oxidation rates with Arrhenius activation energies which strongly depend upon AlAs mole fraction are found The latter produces strong oxidation selectivity between AlGaAs layers with slightly differing Al-content Oxidation selectivity to thickness is also shown for layer thickness <60 nm Differences between the properties of buried oxides converted from AlGaAs and AlAs layers and the impact on selectively oxidized vertical cavity laser lifetime are reported
310 citations
TL;DR: In this paper, a new approach to dielectric metasurface design relies on a single resonator per unit cell and produces robust, high quality factor Fano resonances.
Abstract: We present a new approach to dielectric metasurface design that relies on a single resonator per unit cell and produces robust, high quality factor Fano resonances. Our approach utilizes symmetry breaking of highly symmetric resonator geometries, such as cubes, to induce couplings between the otherwise orthogonal resonator modes. In particular, we design perturbations that couple “bright” dipole modes to “dark” dipole modes whose radiative decay is suppressed by local field effects in the array. Our approach is widely scalable from the near-infrared to radio frequencies. We first unravel the Fano resonance behavior through numerical simulations of a germanium resonator-based metasurface that achieves a quality factor of ∼1300 at ∼10.8 μm. Then, we present two experimental demonstrations operating in the near-infrared (∼1 μm): a silicon-based implementation that achieves a quality factor of ∼350; and a gallium arsenide-based structure that achieves a quality factor of ∼600, the highest near-infrared qualit...
252 citations
Patent•
27 Mar 2014
TL;DR: By doping an organic compound functioning as an electron donor (hereinafter referred to as donor molecules) into an organics layer contacting a cathode, donor levels can be formed between respective LUMO (lowest unoccupied molecular orbital) levels between the cathode and the organic compound layer, and therefore electrons can be injected from the cathodes, and transmission of the injected electrons can also be performed with good efficiency as discussed by the authors.
Abstract: By doping an organic compound functioning as an electron donor (hereinafter referred to as donor molecules) into an organic compound layer contacting a cathode, donor levels can be formed between respective LUMO (lowest unoccupied molecular orbital) levels between the cathode and the organic compound layer, and therefore electrons can be injected from the cathode, and transmission of the injected electrons can be performed with good efficiency. Further, there are no problems such as excessive energy loss, deterioration of the organic compound layer itself, and the like accompanying electron movement, and therefore an increase in the electron injecting characteristics and a decrease in the driver voltage can both be achieved without depending on the work function of the cathode material.
236 citations
References
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TL;DR: In this article, a new process for fabrication of vertical-cavity surface-emitting laser based on the selective conversion of high-Al composition epitaxial AlGaAs to a stable native oxide using "wet oxidation" is presented.
Abstract: Data are presented characterizing a new process for fabrication of vertical‐cavity surface‐emitting lasers based on the selective conversion of high Al composition epitaxial AlGaAs to a stable native oxide using ‘‘wet oxidation.’’ The native oxide is used to form a ring contact to the laser active region. The resulting laser active regions have dimensions of 8, 4, and 2 μm. The lowest threshold laser is achieved with the 8‐μm active region, with a minimum threshold current of 225‐μA continuous wave at room temperature.
596 citations
TL;DR: In this article, a selective conversion of high composition (AlAs)x(GaAs)1−x layers into dense transparent native oxide by reaction with H2O vapor (N2 carrier gas) at elevated temperatures (400 °C) is presented.
Abstract: Data are presented on the conversion (selective conversion) of high‐composition (AlAs)x(GaAs)1−x layers, e.g., in AlxGa1−xAs‐AlAs‐GaAs quantum well heterostructures and superlattices (SLs), into dense transparent native oxide by reaction with H2O vapor (N2 carrier gas) at elevated temperatures (400 °C). Hydrolyzation oxidation of a fine‐scale AlAs(LB)‐GaAs(Lz) SL (LB +Lz≲100 A), or random alloy AlxGa1−xAs (x≳0.7), is observed to proceed more slowly and uniformly than a coarse‐scale ‘‘alloy’’ such as an AlAs‐GaAs superlattice with LB + Lz≳200 A.
561 citations
TL;DR: In this paper, an index-guided vertical cavity top-surface emitting laser diodes have been fabricated from an all epitaxial structure with conducting mirrors by selective lateral oxidation of AlGaAs.
Abstract: Index-guided vertical cavity top-surface emitting laser diodes have been fabricated from an all epitaxial structure with conducting mirrors by selective lateral oxidation of AlGaAs At low voltage, a 78% slope efficiency, and a 350 mu A threshold current in a single device combine to yield a maximum power conversion efficiency of 50% at less than a 2 mA drive current The device operates in a single mode up to 15 mW >
388 citations
"Fabrication and performance of sele..." refers background in this paper
...The latter oxide-confined lasers have exhibited the highest power conversion efficiency (>50%), [ 8 ] lowest threshold current density (90 A/cm2 per quantum well), [9] and lowest threshold voltage (50 mV above photon energy) [7] reported to date for VCSEL's....
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TL;DR: In this article, a vertical-cavity surface emitting laser fabricated using selective oxidation to form a current aperture under a top monolithic distributed Bragg reflector mirror is reported.
Abstract: Novel vertical-cavity surface emitting lasers fabricated using selective oxidation to form a current aperture under a top monolithic distributed Bragg reflector mirror are reported. Large cross-sectional area lasers (259 µm2) exhibit threshold current densities of 150 A/cm2 per quantum well and record low threshold voltage of 1.33 V. Smaller lasers (36 µm2) possess threshold currents of 900 µA with maximum output powers greater than 1 mW. The record performance of these oxidised vertical-cavity lasers arises from the low mirror series resistance and very efficient current injection into the active region.
349 citations
TL;DR: In this article, an index-guided InGaAs/GaAlAs vertical-cavity surface-emitting laser with a native oxide confinement structure has been proposed and fabricated.
Abstract: An index-guided InGaAs/GaAlAs vertical-cavity surface-emitting laser with a native oxide confinement structure has been proposed and fabricated. A record threshold current of 70 µA was achieved with a 5 µm-diameter core device. The proposed structure provides strong electrical and optical confinements. Also a reduction in nonradiative recombination and an improvement in the thermal resistance can be expected.
179 citations