| 1. |
- Lindberg, Hans, 1977, et al.
(author)
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High-power optically pumped 1550-nm VECSEL with a bonded silicon heat spreader
- 2004
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In: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 16:5, s. 1233-1235
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Journal article (peer-reviewed)abstract
- We present an optically pumped 1550-nm vertical-external-cavity surface-emitting laser with improved output power and operating temperature using a bonded heat spreader. The laser comprises an InGaAsP-based gain element, with a resonant periodic gain structure on top of a distributed Bragg reflector, and a high reflectivity spherical mirror as the external reflector. Heat transport is enhanced by a Si heat spreader bonded to the InGaAsP surface by liquid capillary bonding. Optical pumping is achieved using a 1250-nm fiber Raman laser. A maximum continuous output power of 250 mW was obtained under multitransverse mode operation at 240 K. Under operation in the fundamental near-Gaussian mode, we obtained a maximum power of 230 mW with a beam quality factor (M-2) of 1.22. At room temperature, the output power was limited to 12 mW.
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| 2. |
- Lindberg, Hans, 1977, et al.
(author)
-
InP-based optically pumped VECSEL operating CW at 1550 nm
- 2004
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In: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 16:2, s. 362-364
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Journal article (peer-reviewed)abstract
- We present a vertical external-cavity surface-emitting laser operating at 1550 run. The laser comprises an InGaAsP-based gain element, with a resonant periodic gain structure on top of a distributed Bragg reflector, and a high reflectivity spherical mirror as the external reflector. Optical pumping is achieved using a 1250-nm fiber Raman laser. A maximum continuous output power of 70 mW was obtained under multitransverse mode operation at 233 K. Under single-mode operation, we obtained a maximum power of 60 mW with a beam quality factor M-2 less than 1.1.
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| 3. |
- Borgentun, Carl, 1979, et al.
(author)
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Method for measuring reflectance of semiconductor disk laser gain element under optical pump excitation
- 2011
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In: Conference on Lasers and Electro-Optics (CLEO), Baltimore, USA, 1-6/5 2011. - Washington, D.C. : OSA.
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Conference paper (other academic/artistic)abstract
- We present a new measurement method for measuring the spectral reflectance of a semiconductor disk laser gain element under optical pumping, providing valuable information on the spectral dependence of gain under close-to-normal operating conditions.
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| 4. |
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| 5. |
- Adolfsson, Göran, 1981, et al.
(author)
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Direct observation of lateral carrier diffusion in ridge waveguide InGaNAs lasers
- 2009
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In: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 21:134, s. 134-136
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Journal article (peer-reviewed)abstract
- We present results from measurements of the subthreshold lateral spontaneous emission profile in 1.3-mu m wavelength ridge waveguide InGaNAs quantum-well lasers using a scanning near-field optical microscopy technique. The measurements reveal the presence of significant lateral carrier diffusion which has a profound effect on the temperature dependence of the threshold current. This effect is frequently omitted when the characteristic temperature of the threshold current is considered.
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| 6. |
- Adolfsson, Göran, 1981, et al.
(author)
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Effects of Lateral Diffusion on the Temperature Sensitivity of the Threshold Current for 1.3 um Double Quantum-Well GaInNAs/GaAs Lasers
- 2008
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In: IEEE Journal of Quantum Electronics. ; 44:7, s. 607-616
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Journal article (peer-reviewed)abstract
- We present an experimental and theoretical investigationof the temperature dependence of the threshold current fordouble quantum well GaInNAs–GaAs lasers in the temperaturerange 10 C–110 C. Pulsed measurements of the threshold current have been performed on broad and narrow ridge wave guide(RWG) lasers. The narrow RWG lasers exhibit high characteristic temperatures (T0)of 200 K up to a critical temperature (Tc), above which T0 is reduced by approximately a factor of 2. The T0-values for broad RWG lasers are significantly lower than those for the narrow RWG lasers, with characteristic temperatures on the order of 100 (60) K below (above). Numerical simulations, using a model that accounts for lateral diffusion effects, show good agreement with experimental data and reveal that a weakly temperature dependent lateral diffusion current dominates thethreshold current for narrow RWG lasers.
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| 7. |
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| 8. |
- Adolfsson, Göran, 1981, et al.
(author)
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Realization of spectrally engineered semiconductor Fabry-Perot lasers with narrow geometrical tolerances
- 2011
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 109:9, s. 093112-
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Journal article (peer-reviewed)abstract
- Spectrally engineered semiconductor Fabry-Perot laser resonators are designed to enhance the optical feedback for selected longitudinal modes, which thereby require less gain for lasing. This is achieved by introducing refractive index perturbations along the length of the resonator. However,the physical realization of these resonators is a challenge because of very narrow tolerances; in particular the need for precise positioning of the end facets of the resonator in relation to the perturbations, and the excess propagation loss associated with the perturbations, has been a majorconcern. We report on a method to achieve high-quality end facet mirrors enabling precise positioning relative to the perturbations, the latter which are realized as lateral corrugations of the waveguide. Measurements show that the mirror quality is comparable to that of cleaved mirrorsand that the additional loss introduced by the perturbations adds
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| 9. |
- Adolfsson, Göran, 1981, et al.
(author)
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Spectral engineering of semiconductor Fabry–Perot laser cavities in the weakly and strongly perturbed regimes
- 2010
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In: Journal of the Optical Society of America B: Optical Physics. - 1520-8540 .- 0740-3224. ; 27:1, s. 118-127
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Journal article (peer-reviewed)abstract
- By inserting index perturbations at certain positions along a semiconductor Fabry–Perot laser cavity thethreshold gain for one or several of the longitudinal cavity modes can be selectively lowered to facilitate, e.g.,single-mode or two-color operation. Previous design methods were limited to a fairly small number of perturbations,leading to only weakly perturbed cavities and thus a limited freedom in tailoring the spectral propertiesof the laser. In our approach we fully account for all multiple-reflection events and use a search spacethat permits any distribution of the locations and lengths of the perturbations. We are therefore able to designcavities with almost arbitrary spectral properties with very low threshold gain values for, e.g., the lasingmodes of a two-color cavity. Constraining the design by reducing the geometrical freedom, which can be used toincrease the smallest feature size to simplify fabrication, we seamlessly approach the weakly perturbed regimewhile maintaining much of the freedom for spectral engineering.
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| 10. |
- Arafin, S., et al.
(author)
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Comprehensive analysis of electrically-pumped GaSb-based VCSELs
- 2011
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In: Optics Express. - 1094-4087 .- 1094-4087. ; 19:18, s. 17267-17282
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Journal article (peer-reviewed)abstract
- This paper discusses several performance-related aspects of electrically-pumped GaSb-based buried tunnel junction VCSELs with an emission wavelength of 2.6 mu m based on theoretical and experimental results. These results allow a deeper insight into the internal device physics, such as radial diffusion of carriers, maximum continuous-wave operating temperature, diffraction loss, internal temperature, gain and loss parameters, internal quantum efficiency of the active region etc. These parameters can be taken into account while designing mid-infrared lasers which leads to an improved device performance. A simple thermal model of the devices based on the two-dimensional (2-D) finite element method using the material data from the literature is also presented. In addition, an application-based result utilizing these lasers for the measurement of absolute water vapor concentration by wavelength modulation spectroscopy (WMS) method are also described, hinting that devices are well-suited for the targeted sensing applications.
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