The Experts below are selected from a list of 22506 Experts worldwide ranked by ideXlab platform
N K Dutta - One of the best experts on this subject based on the ideXlab platform.
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performance of gain guided surface emitting lasers with semiconductor distributed Bragg Reflectors
IEEE Journal of Quantum Electronics, 1991Co-Authors: G Hasnain, L Yang, Yeongher Wang, J D Wynn, R J Fischer, B E Weir, N K DuttaAbstract:The performance limitations of gain-guided vertical cavity surface emitting lasers (VCSELs) which use epitaxially grown semiconductor distributed Bragg Reflectors (DBRs) are discussed. The light-current (L-I) characteristics and emission wavelength of such lasers are examined as a function of temperature and time under continuous wave (CW) and pulsed operation. The authors observed a sharp roll-over in the CW L-I characteristics which limits the maximum output power. The threshold current under CW operation is found to be lower than that obtained under pulsed conditions. Several microseconds long delay in lasing turn-on is also observed. It is shown quantitatively that these anomalies are a consequence of severe heating effects. It is shown that reduction of the series resistance and threshold current density can lead to significant improvements in the power performance of VCSELs. >
Isamu Akasaki - One of the best experts on this subject based on the ideXlab platform.
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gan based vertical cavity surface emitting lasers with alinn gan distributed Bragg Reflectors
Reports on Progress in Physics, 2019Co-Authors: Tetsuya Takeuchi, Satoshi Kamiyama, Motoaki Iwaya, Isamu AkasakiAbstract:This paper describes the status and prospects of gallium nitride-based vertical-cavity surface-emitting lasers (VCSELs) with semiconductor-based distributed Bragg Reflectors. These optoelectronic devices, which emit laser light from the violet to green region, are expected to be a superior light source for the next-generation of displays and illumination, such as retinal scanning displays and adaptive headlights. The development status and prospects are discussed in comparison with already commercialized gallium arsenide-based infrared VCSELs.
Olav Solgaard - One of the best experts on this subject based on the ideXlab platform.
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Fano resonances in integrated silicon Bragg Reflectors for sensing applications
Optics express, 2013Co-Authors: Chia-ming Chang, Olav SolgaardAbstract:We investigate theoretically and experimentally Fano resonances in integrated silicon Bragg Reflectors. These asymmetric resonances are obtained by interference between light reflected from the Bragg waveguide and from the end facet. The Bragg Reflectors were designed and modeled using the 1D transfer matrix method, and they were fabricated in standard silicon wafers using a CMOS-compatible process. The results show that the shape and asymmetry of the Fano resonances depend on the relative phase of the reflected light from the Bragg Reflectors and end facet. This phase relationship can be controlled to optimize the lineshapes for sensing applications. Temperature sensing in these integrated Bragg Reflectors are experimentally demonstrated with a temperature sensitivity of 77 pm/°C based on the thermo-optic effect of silicon.
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integrated silicon photonic temperature sensors based on Bragg Reflectors with asymmetric fano lineshapes
International Conference on Group IV Photonics, 2012Co-Authors: Chia-ming Chang, Olav SolgaardAbstract:We investigate theoretically and experimentally temperature sensors based on asymmetric Fano resonances in integrated silicon Bragg Reflectors. A temperature sensitivity of 77pm/°C can be achieved due to thermo-optic effect of silicon.
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Asymmetric fano lineshapes in integrated silicon Bragg Reflectors
Conference on Lasers and Electro-Optics 2012, 2012Co-Authors: Chia-ming Chang, Olav SolgaardAbstract:Asymmetric Fano resonances in monolithic silicon Bragg Reflectors are demonstrated. Optimization of the lineshapes is achieved by controlling the phase of the reflected light from the Bragg Reflectors.
Zlatko Sitar - One of the best experts on this subject based on the ideXlab platform.
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high reflectivity iii nitride uv c distributed Bragg Reflectors for vertical cavity emitting lasers
Journal of Applied Physics, 2016Co-Authors: Alexander Franke, Marc P Hoffmann, Ronny Kirste, Milena Bobea, James Tweedie, Felix Kaess, Michael Gerhold, Ramon Collazo, Zlatko SitarAbstract:UV-C distributed Bragg Reflectors (DBRs) for vertical cavity surface emitting laser applications and polariton lasers are presented. The structural integrity of up to 25 layer pairs of AlN/Al0.65Ga0.35N DBRs is maintained by balancing the tensile and compressive strain present between the single layers of the multilayer stack grown on top of an Al0.85Ga0.35N template. By comparing the structural and optical properties for DBRs grown on low dislocation density AlN and AlGaN templates, the criteria for plastic relaxation by cracking thick nitride Bragg Reflectors are deduced. The critical thickness is found to be limited mainly by the accumulated strain energy during the DBR growth and is only negligibly affected by the dislocations. A reflectance of 97.7% at 273 nm is demonstrated. The demonstrated optical quality and an ability to tune the resonance wavelength of our resonators and microcavity structures open new opportunities for UV-C vertical emitters.
R J Molnar - One of the best experts on this subject based on the ideXlab platform.
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high reflectivity ultraviolet algan algan distributed Bragg Reflectors
Applied Physics Letters, 2006Co-Authors: Oleg Mitrofanov, Stefan Schmult, M J Manfra, T Siegrist, Nils Weimann, A M Sergent, R J MolnarAbstract:We demonstrate high-reflectivity crack-free Al0.18Ga0.82N∕Al0.8Ga0.2N distributed Bragg Reflectors (DBR) for the spectral region around 350nm grown by molecular-beam epitaxy on thick GaN templates. The structural quality of the DBR layers is maintained by compensating the compressive and tensile stress in each λ∕4 pair. This approach results in the lowest elastic strain energy and allows the growth of thick coherently strained DBRs. A 25 period mirror provides a 26nm wide stop band centered at 347nm with the maximum reflectivity higher than 99%.