Simulation and Design of a Compact GaAs Based Tunable Dual-wavelength Diode Laser System PDF Download

Author: Jan-Philipp Koester
Publisher:
ISBN:
Category :
Languages : en
Pages :

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We present our design of a compact, integrated and tunable dual-wavelength diode laser system emitting around 785 nm, which is of interest for several applications like Raman spectroscopy and the generation of THz radiation. To achieve a more compact device compared to previous GaAs based designs two etch depths are realized, leading to shallowly etched ridge waveguides in regions were optical gain is applied and deeply etched waveguides used to enable compact integrated waveguide components. The device parameters are optimized using a numerically efficient simulation tool for passive waveguides. Subsequently, the entire laser system is further analyzed applying a sophisticated traveling-wave equation based model for active devices giving access to internal intensity and carrier density distributions. It is shown that active laser simulations all-passive simulation.

Author: Jan-Philipp Koester
Publisher: Cuvillier Verlag
ISBN: 3736968825
Category :
Languages : en
Pages : 171

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Edge-emitting quantum-well diode lasers based on GaAs combine a high conversion efficiency, a wide range of emission wavelengths covering a span from 630 nm to 1180 nm, and the ability to achieve high output powers. The often used longitudinal-invariant Fabry-Pérot-type resonators are easy to design but often lead to functionality or performance limitations. In this work, the application of laterally-longitudinally non-uniform resonator configurations is explored as a way to reduce unwanted and performance-limiting effects. The investigations are carried out on existing and entirely newly developed laser designs using dedicated simulation tools. These include a sophisticated time-dependent laser simulator based on a traveling-wave model of the optical fields in the lateral-longitudinal plane and a Maxwell solver based on the eigenmode expansion method for the simulation of passive waveguides. Whenever possible, the simulation results are compared with experimental data. Based on this approach, three fundamentally different laser types are investigated: • Dual-wavelength lasers emitting two slightly detuned wavelengths around 784 nm out of a single aperture • Ridge-waveguide lasers with tapered waveguide and contact layouts that emit light of a wavelength of around 970 nm • Broad-area lasers with slightly tapered contact layouts emitting at 910 nm The results of this thesis underline the potential of lateral-longitudinal non-uniform laser designs to increase selected aspects of device performance, including beam quality, spectral stability, and output power.

Author: Thorben Kaul
Publisher: Cuvillier Verlag
ISBN: 3736963963
Category : Science
Languages : en
Pages : 136

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This work presents progress in the root-cause analysis of power saturation mechanisms in continuous wave (CW) driven GaAs-based high-power broad area diode lasers operated at 935 nm. Target is to increase efficiency at high optical CW powers by epitaxial design. The novel extreme triple asymmetric (ETAS) design was developed and patented within this work to equip diode lasers that use an extremely thin p-waveguide with a high modal gain. An iterative variation of diode lasers employing ETAS designs was used to experimentally clarify the impact of modal gain on the temperature dependence of internal differential quantum efficiency (IDQE) and optical loss. High modal gain leads to increased free carrier absorption from the active region. However, less power saturation is observed, which must then be attributed to an improved temperature sensitivity of the IDQE. The effect of longitudinal spatial hole burning (LSHB) leads to above average non-linear carrier loss at the back facet of the device. At high CW currents the junction temperature rises. Therefore, not only the asymmetry of the carrier profile increases but also the average carrier density in order to compensate for the decreased material gain and increased threshold gain. This carrier non-pinning effect above threshold is found in this work to enhance the impact of LSHB already at low currents, leading to rapid degradation of IDQE with temperature. This finding puts LSHB into a new context for CW-driven devices as it emphasizes the importance of low carrier densities at threshold. The carrier density was effectively reduced by applying the novel ETAS design. This enabled diode lasers to be realized that show minimized degradation of IDQE with temperature and therefore improved performance in CW operation.

Author: Anissa Zeghuzi
Publisher: Cuvillier Verlag
ISBN: 3736962894
Category : Science
Languages : en
Pages : 176

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Broad-area lasers are edge-emitting semiconductor lasers with a wide lateral emission aperture. This feature enables high output powers but also diminishes the lateral beam quality and results in their inherently non-stationary behavior. Research in the area is driven by application, and the main objective is to increase the brightness, which includes both output power and lateral beam quality. To understand the underlying spatio-temporal phenomena and to apply this knowledge in order to reduce costs for brightness optimization, a self-consistent simulation tool taking all essential processes into account is vital. Firstly, in this work a quasi-three-dimensional opto-electronic and thermal model is presented that describes essential qualitative characteristics of real devices well. Time-dependent traveling-wave equations are utilized to characterize the inherently non-stationary optical fields, which are coupled to dynamic rate equations for the excess carriers in the active region. This model is extended by an injection-current-density model to accurately include lateral current spreading and spatial hole burning. Furthermore, a temperature model is presented that includes short-time local heating near the active region as well as the formation of a stationary temperature profile. Secondly, the reasons of brightness degradation, i.e. the origins of power saturation and the spatially modulated field profile, are investigated. And lastly, designs that mitigate those effects limiting the lateral brightness under pulsed and continuous-wave operation are discussed. Amongst those designs a novel “chessboard laser” is presented that utilizes longitudinal-lateral gain-loss modulation and an additional phase tailoring to obtain a very low far-field divergence.

Author: Jan-Philipp Koester
Publisher:
ISBN: 9783736978829
Category :
Languages : en
Pages : 0

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Author: Tim David Germann
Publisher: Springer Science & Business Media
ISBN: 3642340792
Category : Technology & Engineering
Languages : en
Pages : 157

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Semiconductor heterostructures represent the backbone for an increasing variety of electronic and photonic devices, for applications including information storage, communication and material treatment, to name but a few. Novel structural and material concepts are needed in order to further push the performance limits of present devices and to open up new application areas. This thesis demonstrates how key performance characteristics of three completely different types of semiconductor lasers can be tailored using clever nanostructure design and epitaxial growth techniques. All aspects of laser fabrication are discussed, from design and growth of nanostructures using metal-organic vapor-phase epitaxy, to fabrication and characterization of complete devices.

Author: Mohamed Elattar
Publisher: Cuvillier Verlag
ISBN: 3689520479
Category :
Languages : en
Pages : 124

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Book Description
GaAs-based 9xx-nm broad-area diode lasers (BALs) offer the highest optical power (Popt) among diode lasers and the highest conversion efficiency (ηE) among all light sources. Therefore, they are widely used in material processing applications (e.g. metal cutting), which additionally require high beam quality (i.e. low beam parameter product BPP), typically limited in BALs along the lateral axis (BPPlat). Enhancing BAL performance is dependent on identifying the thermal and non-thermal limiting mechanisms, and implementing design changes to minimize their effects. In this work, two novel approaches based on lateral structuring are developed, aiming to overcome different limiting mechanisms acting along the lateral axis. First, the enhanced self-aligned lateral structure (eSAS) is based on integrating structured current-blocking layers outside the BAL stripe to centrally confine current and charge carriers, thereby suppressing lateral current spreading and lateral carrier accumulation. Two eSAS variants are optimized using simulation tools, then realized in multiple wafer processes, followed by characterization of mounted BALs. eSAS BALs exhibit state-of-the-art Popt and lateral brightness (Popt/BPPlat), with clear benefits over standard gain-guided BALs in terms of threshold, BPPlat and peak ηE. The second approach is chip-internal thermal path engineering, based on structured epitaxial layers replaced outside the stripe by heat-blocking materials to centrally confine heat flow. This flattens the lateral temperature profile (i.e. reduces thermal lensing) around the active zone, which is associated with enhanced brightness. Finite-element thermal simulations are used to estimate the benefits of this approach, thereby motivating its practical realization in future studies.

Author: Roland Diehl
Publisher: Springer Science & Business Media
ISBN: 3540478523
Category : Science
Languages : en
Pages : 420

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Book Description
Starting from the basics of semiconductor lasers with emphasis on the generation of high optical output power the reader is introduced in a tutorial way to all key technologies required to fabricate high-power diode-laser sources. Various applications are exemplified.

Author: Lutz Schneider
Publisher:
ISBN: 9783866281226
Category : Semiconductor lasers
Languages : en
Pages : 131

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Author: William Paul Risk
Publisher: Cambridge University Press
ISBN: 9780521521031
Category : Science
Languages : en
Pages : 540

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Book Description
William Risk, Timothy Gosnell and Arto Nurmikko have brought together their diverse expertise from industry and academia to write the first fully comprehensive book on the generation and application of blue-green lasers. This volume describes the theory and practical implementation of three techniques for the generation of blue-green light: nonlinear frequency conversion of infrared lasers, upconversion lasers, and wide bandgap semiconductor diode lasers. In addition, it looks at the various applications that have driven the development of compact sources of blue-green light, and reflects on the recent application of these lasers in high-density data storage, color displays, reprographics, and biomedical technology. Compact Blue-Green Lasers is suitable for graduate-level courses or as a reference for academics and professionals in optics, applied physics, and electrical engineering.