Design considerations for large-aperture single-mode oxide-confined vertical-cavity surface-emitting lasers

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Appl. Phys. Lett. 101, 071117 (2012) and may be found at https://doi.org/10.1063/1.4746422.The output modal content of the oxide-confined vertical-cavity surface-emitting lasers (VCSELs) crucially depends upon the thickness of the low-index oxide aperture, its position with respect to the standing waves of the transverse-longitudinal modes and the separation from the cavity. Three-dimensional cold-cavity optical modes of typical AlGaAs/GaAs VCSELs at 850 nm were simulated to study these dependencies quantitatively taking into account the field diffraction and the material dispersion. Modification of one or two periods of the distributed Bragg reflector by positioning the thin oxidized aperture layers in the mode nodes allows single-mode regime to extend to the aperture diameters as large as 10 μm.DFG, 43659573, SFB 787: Halbleiter - Nanophotonik: Materialien, Modelle, Bauelement

Carrier-induced refractive index in quantum dot structures due to transitions from discrete quantum dot levels to continuum states

The carrier-induced refractive index in quantum dot (QD) structures due to optical transitions from QD levels to continuum states is considered. It is shown that, for large photon energies, the refractive index change is given asymptotically by the Drude formula. Calculations of the linewidth enhancement factor, alpha, show that alphasimilar to1 due to this contribution to the total refractive index. Furthermore, for highly localized QD states, the absorption coefficient at the photon energies similar to0.8-1.0 eV due to these transitions can be on the order of 10(3) m(-1). (C) 2004 American Institute of Physics. (DOI: 10.1063/1.1639933

Decay dynamics of excitonic polarons in InAs/GaAs quantum dots

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Journal of Applied Physics 110, 074303 (2011) and may be found at https://doi.org/10.1063/1.3639310.We present time-resolved studies of the exciton-phonon interaction in self-assembled InAs/GaAs quantum dots. Different scattering and luminescence processes were investigated by time-resolved spectroscopy exciting resonantly into the quantum dot’s electronic structure. By studying the characteristic decay times of the ground state and of several phonon-assisted recombinations we were able to distinguish a resonant Raman process from a phonon-assisted photoluminescence process which are always simultaneously present and can interfere with each other. While lifetimes under 30 ps were observed for the coherent Raman process, the incoherent phonon-assisted recombination exhibited typical lifetimes of around 1 ns independently of the excitation energy. We conclude that under resonant excitation the dominant radiative recombination process in this system always involves an electronic state of the ground state of the quantum dot’s electronic structure. Combining temperature-dependent and time-resolved measurements we show that a weak phonon-bottleneck is present in the low temperature regime (< 130 K), while it disappears for higher temperatures.DFG, 43659573, SFB 787: Halbleiter - Nanophotonik: Materialien, Modelle, BauelementeDFG, 53182490, EXC 314: Unifying Concepts in Catalysi

81 fJ/bit energy-to-data ratio of 850 nm vertical-cavity surface-emitting lasers for optical interconnects

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Appl. Phys. Lett. 98, 231106 (2011) and may be found at https://doi.org/10.1063/1.3597799.Extremely energy-efficient oxide-confined high-speed 850 nm vertical-cavity surface-emitting lasers for optical interconnects are presented. Error-free performance at 17 and 25 Gb/s via a 100 m multimode fiber link is demonstrated at record high dissipation-power-efficiencies of up to 69 fJ/bit (<0.1mW/Gbps) and 99 fJ/bit, respectively. These are the most power efficient high-speed directly modulated light sources reported to date. The total energy-to-data ratio is 83 fJ/bit at 25°C and reduces to 81 fJ/bit at 55°C. These results were obtained without adjustment of driving conditions. A high -factor of 12.0GHz/(mA)0.5 and a -factor of 0.41 ns are measured.EC/FP7/224211/EU/VISIT - Vertically Integrated Systems for Information Transfer/VISITDFG, 43659573, SFB 787: Halbleiter - Nanophotonik: Materialien, Modelle, Bauelement

Frequency response of large aperture oxide-confined 850 nm vertical cavity surface emitting lasers

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Appl. Phys. Lett. 95, 131101 (2009) and may be found at https://doi.org/10.1063/1.3231446.Small and large signal modulation measurements are carried out for 850 nm vertical cavity surface emitting lasers (VCSELs). The resonance frequency, damping factor, parasitic frequency, and -factor are extracted. Small signal modulation bandwidths larger than 20 GHz are measured. At larger currents the frequency response becomes partially limited by the parasitics and damping. Our results indicate that by increasing the parasitic frequency, the optical 3 dB bandwidth may be extended to ∼25GHz. A decrease in the damping should enable VCSEL bandwidths of 30 GHz for current densities not exceeding ∼10kA/cm2 and ultimately error-free optical links at up to 40 Gbit/s.DFG, 43659573, SFB 787: Halbleiter - Nanophotonik: Materialien, Modelle, BauelementeEC/FP7/224211/EU/VISIT - Vertically Integrated Systems for Information Transfer/VISI

Ultrahigh-brightness 850 nm GaAs/AlGaAs photonic crystal laser diodes

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Appl. Phys. Lett. 93, 221102 (2008) and may be found at https://doi.org/10.1063/1.3040322.One-dimensional photonic crystal lasers emitting in the 850 nm range show high internal quantum efficiencies of 93% and very narrow vertical beam divergence of 7.1° (full width at half maximum). 50m broad area lasers with unpassivated facets exhibit a high total output power of nearly 20 W in pulsed mode with a divergence of 9.5°×11.3° leading to a record brightness of 3×108Wcm−2sr−1, being presently the best value ever reported for a single broad area laser diode. 100m broad devices with unpassivated facets show continuous wave operation with an output power of 1.9 W.DFG, 43659573, SFB 787: Halbleiter - Nanophotonik: Materialien, Modelle, Bauelement

Advanced methods for strain measurement in crystalline nanomaterials: application to multilayer InAlGaP quantum dots formed on high-index (11l)GaAs substrates”

International audienc

Advanced methods for strain measurement in crystalline nanomaterials: application to multilayer InAlGaP quantum dots formed on high-index (11l)GaAs substrates”

International audienc

Design optimization for bright electrically-driven quantum dot single-photon sources emitting in telecom O-band

© 2021 Optica Publishing Group. Users may use, reuse, and build upon the article, or use the article for text or data mining, so long as such uses are for non-commercial purposes and appropriate attribution is maintained. All other rights are reserved.A combination of advanced light engineering concepts enables a substantial improvement in photon extraction efficiency of micro–cavity–based single–photon sources in the telecom O–band at ∼1.3 µm. We employ a broadband bottom distributed Bragg reflector (DBR) and a top DBR formed in a dielectric micropillar with an additional circular Bragg grating in the lateral plane. This device design includes a doped layer in pin–configuration to allow for electric carrier injection. It provides broadband (∼8–10 nm) emission enhancement with an overall photon–extraction efficiency of ∼83% into the upper hemisphere and photon–extraction efficiency of ∼79% within numerical aperture NA=0.7. The efficiency of photon coupling to a single–mode fiber reaches 11% for SMF28 fiber (with NA=0.12), exceeds 22% for 980HP fiber (with NA=0.2) and reaches ∼40% for HNA fiber (with NA=0.42) as demonstrated by 3D finite–difference time–domain modeling