| 1. |
- Asplund, C., et al.
(författare)
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Doping-induced losses in AlAs/GaAs distributed Bragg reflectors
- 2001
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 90:2, s. 794-800
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Tidskriftsartikel (refereegranskat)abstract
- We have studied n- and p-type doping-induced performance degradation of AlAs/GaAs distributed Bragg reflectors (DBRs) for applications in vertical cavity lasers (VCLs). Based on high-accuracy optical reflectance and triple-axis x-ray diffraction measurements on a variety of differently doped DBR structures grown by metalorganic vapor-phase epitaxy, a fitting procedure was employed to extract the doping-dependent optical loss. A striking observation is that the reflectance of these DBRs is much more sensitive to n- than p-type doping incorporation. While in the latter case the loss can be well accounted for by intervalence-band and free-carrier absorption, additional loss mechanisms must be considered for n-type DBRs. We relate the losses to doping-enhanced interdiffusion effects resulting in increased interface scattering. These findings should have important consequences for the design of VCLs, demonstrating the importance of reduced n-type doping concentrations and/or growth temperatures, or the application of alternative device concepts, e.g., employing intracavity contacts.
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| 2. |
- Gilet, Ph., et al.
(författare)
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1.3 μm VCSELs : InGaAs/GaAs, GaInNAs/GaAs multiple quantum wells and InAs/GaAs quantum dots- Three candidates as active material
- 2007
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Ingår i: Vertical - Cavity Surface - Emitting Lasers XI. - San Jose, CA : SPIE. ; , s. F4840-F4840
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Konferensbidrag (refereegranskat)abstract
- In this article, we report our results on 1.3ÎŒm VCSELs for optical interconnection applications. Room temperature continuous-wave lasing operation is demonstrated for top emitting oxide-confined devices with three different active materials, highly strained InGaAs/GaAs(A) and GalnNAs/GaAs (B) multiple quantum wells (MQW) or InAs/GaAs (C) quantum dots (QD). Conventional epitaxial structures grown respectively by Metal Organic Vapour Phase Epitaxy (MOVPE), Molecular Beam Epitaxy (MBE) and MBE, contain rully doped GaAs/AlGaAs DBRs. All three epilayers are processed in the same way. Current and optical confinement are realized by selective wet oxidation. Circular apertures from 2 ÎŒm to 16 ÎŒm diameters are defined. At room temperature and in continuous wave operation, all three systems exhibit lasing operation at wavelengths above 1 275nm and reached 1 300nm for material (A). Typical threshold currents are in the range [1-10]mA and are strongly dependent firstly on oxide diameter and secondly on temperature. Room temperature cw maximum output power corresponds respectively to 1.77mW, 0.5mW and 0.6mW. By increasing driving current, multimode operation occurs at different level depending on the oxide diameter. In case (A), non conventional modal behaviors will be presented and explained by the presence of specific oxide modes. Thermal behaviors of the different devices have been compared. In case (A) and (C) we obtain a negative T0. We will conclude on the different active materials in terms of performances with respect to 1300nm VCSEL applications.
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| 3. |
- Hammar, Mattias, et al.
(författare)
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1.3-mu m InGaAs vertical-cavity surface-emitting lasers
- 2005
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Ingår i: 2005 IEEE LEOS Annual Meeting Conference Proceedings (LEOS). - 0780392175 ; , s. 396-397
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Konferensbidrag (refereegranskat)abstract
- We report on the fabrication and performance of N-free InGaAs/GaAs 1.3-mu m range vertical-cavity surface-emitting lasers (VCSELs). Using optimized quantum-well (QW) growth conditions in combination with negative gain-cavity tuning, high-performance VCSELs with emission wavelength up to 1300 nm are realized. The performance figures include mA-range threshold currents, mW-range singlemode output power, continuous-wave operation up to 140 degrees C and 10 Gbit/s data transmission.
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| 4. |
- Hammar, Mattias, et al.
(författare)
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Room-temperature operation of 980-nm transistor-vertical-cavity surface-emitting lasers
- 2013
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Ingår i: 2013 IEEE 6th International Conference on Advanced Infocomm Technology, ICAIT 2013. - : IEEE. - 9781479904655 ; , s. 141-142
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Konferensbidrag (refereegranskat)abstract
- We report on the design, fabrication and characterization of pnp-type 980-nm transistor-vertical-cavity surface-emitting lasers (T-VCSELs). Using an epitaxial regrowth process and a triple-intracavity current injection scheme we demonstrate static performance levels quite comparable to those of conventional VCSELs, including sub-mA threshold base current, mW-range output power and continuous-wave operation at least up to 50°C.
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| 5. |
- Mogg, S., et al.
(författare)
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Absolute reflectance measurements by a modified cavity phase-shift method
- 2002
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 73:4, s. 1697-1701
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Tidskriftsartikel (refereegranskat)abstract
- This article reports on a modified cavity phase-shift (CAPS) method for accurate and reliable characterization of high reflectance mirrors. Our approach relies on using a directly modulated Fabry-Perot laser to circumvent the difficulties encountered in previous attempts with the CAPS method. The Fabry-Perot laser diode ensures a constant coupling between the probe laser and test cavity modes. This results in a stable beam intensity transmitted through the test cavity allowing for accurate measurements of the phase shift from which the absolute reflectance can be determined. The experimental arrangement presented in this article is versatile and easy to use. The method is nondestructive and especially suited for the characterization of distributed Bragg reflectors (DBRs) employed in vertical-cavity optoelectronic devices. A premium feature of this method is its capability to probe a relatively small area of less than 1 mm which can be positioned anywhere across the surface of the wafer. We demonstrate the use of the method by measuring the absolute reflectance of metalorganic vapor-phase epitaxy grown AlAs/GaAs DBRs for 1.3 mum vertical-cavity lasers.
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| 6. |
- Mogg, S., et al.
(författare)
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Properties of highly strained InGaAs/GaAs quantum wells for 1.2-mu m laser diodes
- 2002
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 81:13, s. 2334-2336
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Tidskriftsartikel (refereegranskat)abstract
- The properties of 1.2-mum highly strained InGaAs quantum wells (QWs) grown on GaAs substrates have been analyzed. Optical gain spectra versus injection current and temperature, transparency current density, as well as other figures of merit were assessed from measurements on broad-area and ridge-waveguide lasers based on these QWs. Such active regions are of interest for a range of applications, including GaAs-based high-power lasers and vertical-cavity lasers for wavelengths beyond 1.2 mum.
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| 7. |
- Olsson, Fredrik, et al.
(författare)
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Selective area growth of GaInNAs/GaAs by MOVPE
- 2004
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Ingår i: Physica. E, Low-Dimensional systems and nanostructures. - : Elsevier BV. - 1386-9477 .- 1873-1759. ; 23:04-mar, s. 347-351
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Tidskriftsartikel (refereegranskat)abstract
- Selective area growth (SAG) of GaInNAs/GaAs systems has been studied by metalorganic vapor-phase epitaxy (MOVPE) for the first time. This also includes a comparative study of SAG of the GaInAs/GaAs. The patterns consisted of various filling factors (F). The band gap changes and the growth morphology have been investigated. A red-shift observed for SAG GaInAs is similar to100 nm with respect to the planar GaInAs which can be attributed to both In enrichment and quantum well (QW) thickness enhancement. Selectively grown GaInNAs structures exhibit a maximum wavelength of 1.3 mum, corresponding to a red-shift of similar to80 nm with respect to the planar GaInNAs. Atomic force microscopy (AFM) scans reveal a three-dimensional growth behaviour for SAG GaInNAs unlike SAG GaInAs. This can be related to a certain amount of phase separation or strain that are often the signatures of N incorporation. The cathodoluminescence (CL) intensities (spectral line width) for SAG GaInNAs are larger (smaller) than those for SAG GaInAs at low F's but smaller (larger) at high F's. This indicates that at low F's, GaInAs has degraded due to very high strain but certain amount of strain compensation occurs in GaInNAs.
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| 8. |
- Stevens, R., et al.
(författare)
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Microstructured photonic crystal for single-mode long wavelength VCSELs
- 2008
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Ingår i: Semiconductor Lasers and Laser Dynamics III. - : SPIE.
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Konferensbidrag (refereegranskat)abstract
- In this article, we report on long wavelength (1.27 ÎŒm) single-mode micro-structured photonic crystal strained InGaAs quantum wells VCSELs for optical interconnection applications. Single fundamental mode room-temperature continuous-wave lasing operation was demonstrated for devices designed and processed with different two-dimensional etched patterns. The conventional epitaxial structure was grown by Metal-Organic Vapor Phase Epitaxy (MOVPE) and contains fully doped GaAs/AlGaAs DBRs, one oxidation layer and three strained InGaAs quantum wells. The holes were etched half-way through the top-mirror following various designs (triangular and square lattices) and with varying hole's diameters and pitches. We obtained up to 1.7 mW optical output power and more than 30 dB Side-Mode Suppression Ratio (SMSR) at room temperature and in continuous wave operation. Systematic static electrical, optical and spectral characterization was performed on wafer using an automated probe station. Numerical modeling using the MIT Photonic-Bands (MPB [1]) package of the transverse modal behaviors in the photonic crystal was performed using the plane wave method in order to understand the index-guiding effects of the chosen patterns, and to further optimize the design structures for mode selection at the given wavelength.
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| 9. |
- Streubel, K., et al.
(författare)
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Novel technologies for 1.55-mu m vertical cavity lasers
- 2000
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Ingår i: Optical Engineering. - : SPIE-Intl Soc Optical Eng. - 0091-3286 .- 1560-2303. ; 39:2, s. 488-497
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Tidskriftsartikel (refereegranskat)abstract
- We report on three novel vertical-cavity laser (VCL) structures for 1.55-mu m operation. Two of the structures utilize an n-type GalnAsP/InP Bragg mirror combined with an Al(Ga)As/GaAs mirror using either wafer fusion or metamorphic epitaxial growth. The third employs two wafer-fused AlGaAs/GaAs mirrors, in which lateral current confinement is obtained by localized fusion of the p mirror. Ali three VCLs use strained GalnAsP quantum welts as active material and achieve continuous-wave (cw) operation at room temperature or above. The single fused VCL operates up to 17 and 101 degrees C in continuous-wave and pulsed mode, respectively. The monolithic VCL-structure with a metamorphic GaAs/AlAs n-type mirror uses a reverse-biased tunnel junction for current injection. This laser achieves record high output power (1 mW) at room temperature and operates cw up to 45 degrees C. The double fused VCLs with a 10x10-mu m(2) active area operate cw up to 30 degrees C with threshold current as low as 2.5 mA and series resistance of 30 Omega. The emission spectra exhibit a single lasing mode polarized with 30-dB extinction ratio and a spectral linewidth of 150 MHz.
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| 10. |
- Xiang, Yu, et al.
(författare)
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AlGaAs/GaAs/InGaAs pnp-type vertical-cavity surface-emitting transistor-lasers
- 2015
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Ingår i: Optics Express. - 1094-4087. ; 23:12, s. 15680-15699
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Tidskriftsartikel (refereegranskat)abstract
- We report on the design, fabrication and analysis of vertical-cavity surface-emitting transistor-lasers (T-VCSELs) based on the homogeneous integration of an InGaAs/GaAs VCSEL and an AlGaAs/GaAs pnp-heterojunction bipolar transistor (HBT). Epitaxial regrowth confinement, modulation doping, intracavity contacting and non-conducting mirrors are used to ensure a low-loss structure, and a variety of design variations are investigated for a proper internal biasing and current injection to ensure a wide operating range. Optimized devices show mW-range output power, mA-range base threshold current and high-temperature operation to at least 60 degrees C with the transistor in its active mode of operation for base currents well beyond threshold. Current confinement schemes based on pnp-blocking layers or a buried tunnel junction are investigated as well as asymmetric current injection for reduced extrinsic resistances.
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