A 310 nm Optically Pumped AlGaN Vertical-Cavity Surface-Emitting Laser

Hjort, Filip; Enslin, Johannes; Cobet, Munise; Bergmann, Michael Alexander; Gustavsson, Johan S.; Kolbe, Tim; Knauer, A.; Nippert, Felix; Häusler, Ines; Wagner, Markus R.; Wernicke, Tim; Kneissl, Michael; Haglund, Åsa

doi:10.1021/acsphotonics.0c01382

Cited by 25 publications

(20 citation statements)

References 42 publications

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“…Compared to edge-emitting lasers, SE lasers offer a number of advantages such as low beam divergence, circular far-field pattern, fast modulation speed, two-dimensional integration capability, and so on 5 , 7 . Over decades of development, gallium arsenide (GaAs)-based near-infrared (IR) SE lasers have turned into a billion-dollar industry, impacting both data communication and 3D sensing such as face recognition and time-of-flight imaging 8 – 12 . The success of SE lasers in the near-IR unfortunately is not seen in the shorter visible and UV spectral ranges.…”

Section: Introductionmentioning

confidence: 99%

“…AlGaN has received a wide interest for the UV SE laser development due to a number of advantages such as direct, ultrawide, and tunable bandgap energies, chemically stable, mechanically strong, highly compact, and so on. Nonetheless, the electrically injected AlGaN nanowire UV SE lasers demonstrated hitherto are all based on random optical cavities 32 – 35 , whereas AlGaN UV VCSELs are all through optical pumping and are all with large lasing threshold power densities 8 , 11 , 36 – 45 . For instance, the threshold power density for sub-280 nm lasing is 1.2 MW/cm 2 39 , and even for lasing at longer wavelength (e.g., close to 400 nm) the threshold power density is in the range of around 200–400 kW/cm 2 11 , 40 .…”

Section: Introductionmentioning

confidence: 99%

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Ultralow threshold surface emitting ultraviolet lasers with semiconductor nanowires

Vafadar

Zhao

2023

Sci Rep

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Surface-emitting (SE) semiconductor lasers have changed our everyday life in various ways such as communication and sensing. Expanding the operation wavelength of SE semiconductor lasers to shorter ultraviolet (UV) wavelength range further broadens the applications to disinfection, medical diagnostics, phototherapy, and so on. Nonetheless, realizing SE lasers in the UV range has remained to be a challenge. Despite of the recent breakthrough in UV SE lasers with aluminum gallium nitride (AlGaN), the electrically injected AlGaN nanowire UV lasers are based on random optical cavities, whereas AlGaN UV vertical-cavity SE lasers (VCSELs) are all through optical pumping and are all with large lasing threshold power densities in the range of several hundred kW/cm2 to MW/cm2. Herein, we report ultralow threshold, SE lasing in the UV spectral range with GaN-based epitaxial nanowire photonic crystals. Lasing at 367 nm is measured, with a threshold of only around 7 kW/cm2 (~ 49 μJ/cm2), a factor of 100× reduction compared to the previously reported conventional AlGaN UV VCSELs at similar lasing wavelengths. This is also the first achievement of nanowire photonic crystal SE lasers in the UV range. Further given the excellent electrical doping that has already been established in III-nitride nanowires, this work offers a viable path for the development of the long-sought-after semiconductor UV SE lasers.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ultralow threshold surface emitting ultraviolet lasers with semiconductor nanowires

Vafadar

Zhao

2023

Sci Rep

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“…Ultraviolet (UV) distributed Bragg reflectors (DBRs) with high reflectance are essential building blocks to fabricate the vertical-cavity surface-emitting lasers (VCSELs), , resonant-cavity light-emitting diodes (RCLEDs), resonant-cavity photodiodes (RCPD), and the exciton-polariton lasers . For vertical UV LEDs with transparent p-AlGaN, UV DBRs can be used to reflect the downward-traveling light upward, thus enhancing light extraction .…”

Section: Introductionmentioning

confidence: 99%

Nanoporous AlGaN Distributed Bragg Reflectors for Deep Ultraviolet Emission

Shan

Guo

Zhao

et al. 2022

ACS Appl. Nano Mater.

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In this paper, we demonstrated wafer-scale AlGaN-based deep ultraviolet (DUV) nanoporous (NP) distributed Bragg reflectors (DBRs) by vertical electrochemical (EC) etching. The stopbands of the NP-DBRs were centered around 280 nm with reflectance close to 90%. A thick AlGaN film and four-period multiple quantum wells (MQWs) were grown on the strain-relaxed NP-DBRs template. The reciprocal space mappings (RSMs) revealed the increased compressive strain in MQWs grown on NP-DBRs, and transverse electric (TE) mode emission was enhanced due to this strain modulation. Thanks to the reflection effect, the photoluminescence (PL) intensity of the MQWs in the NP-DBR region was more than twice that of the region without NP-DBRs. The anisotropic optical polarization measurements and theoretical simulations demonstrated that the light extraction of both TE and transverse magnetic (TM) modes were improved by reflection, and the sideward light can be deflected upward by scattering by the etched nanovoids. Especially, the TM mode light was more extracted by NP-DBRs. Our work highlighted the possible applications enabled by the DUV NP-DBRs in light reflection and structural reconstructions of AlGaNbased UV emitters.

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“…The p-type doping of AlGaN is particularly challenging [6], and the high doping concentrations required to achieve p-type conductivity degrade the material quality and increase absorption losses. This is one of the main reasons why laser diodes emitting below 370 nm show a dramatic increase in threshold current density [7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

AlGaN/GaN asymmetric graded-index separate confinement heterostructures designed for electron-beam pumped UV lasers

et al. 2021

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We present a study of undoped AlGaN/GaN separate confinement heterostructures designed to operate as electron beam pumped ultraviolet lasers. We discuss the effect of spontaneous and piezoelectric polarization on carrier diffusion, comparing the results of cathodoluminescence with electronic simulations of the band structure and Monte Carlo calculations of the electron trajectories. Carrier collection is significantly improved using an asymmetric graded-index separate confinement heterostructure (GRINSCH). The graded layers avoid potential barriers induced by polarization differences in the heterostructure and serve as strain transition buffers which reduce the mosaicity of the active region and the linewidth of spontaneous emission.

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A 310 nm Optically Pumped AlGaN Vertical-Cavity Surface-Emitting Laser

Cited by 25 publications

References 42 publications

Ultralow threshold surface emitting ultraviolet lasers with semiconductor nanowires

Ultralow threshold surface emitting ultraviolet lasers with semiconductor nanowires

Nanoporous AlGaN Distributed Bragg Reflectors for Deep Ultraviolet Emission

AlGaN/GaN asymmetric graded-index separate confinement heterostructures designed for electron-beam pumped UV lasers

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