Analysis of Spatio-Temporal Phenomena in High-Brightness Diode Lasers using Numerical Simulations - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Analysis of Spatio-Temporal Phenomena in High-Brightness Diode Lasers using Numerical Simulations write by Anissa Zeghuzi. This book was released on 2020-10-22. Analysis of Spatio-Temporal Phenomena in High-Brightness Diode Lasers using Numerical Simulations available in PDF, EPUB and Kindle. 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.
Design, simulation and analysis of laterally-longitudinally non-uniform edge-emitting GaAs-based diode lasers (Band 73)
Design, simulation and analysis of laterally-longitudinally non-uniform edge-emitting GaAs-based diode lasers (Band 73) - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Design, simulation and analysis of laterally-longitudinally non-uniform edge-emitting GaAs-based diode lasers (Band 73) write by Jan-Philipp Koester. This book was released on 2023-09-19. Design, simulation and analysis of laterally-longitudinally non-uniform edge-emitting GaAs-based diode lasers (Band 73) available in PDF, EPUB and Kindle. 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.
A compact mode-locked diode laser system for high precision frequency comparison experiments (Band 64)
A compact mode-locked diode laser system for high precision frequency comparison experiments (Band 64) - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook A compact mode-locked diode laser system for high precision frequency comparison experiments (Band 64) write by Heike Christopher. This book was released on 2021-04-09. A compact mode-locked diode laser system for high precision frequency comparison experiments (Band 64) available in PDF, EPUB and Kindle. Optical frequency combs (OFC) have revolutionized various applications in applied and fundamental sciences that rely on the determination of absolute optical frequencies and frequency differences. The latter requires only stabilization of the spectral distance between the individual comb lines of the OFC, allowing to tailor and reduce system complexity of the OFC generator (OFCG). One such application is the quantum test of the universality of free fall within the QUANTUS experimental series. Within the test, the rate of free fall of two atomic species, Rb and K, in micro-gravity will be compared. The aim of this thesis was the development of a highly compact, robust, and space-suitable diode laser-based OFCG with a mode-locked optical spectrum in the wavelength range around 780 nm. A diode laser-based OFCG was developed, which exceeds the requirements with a spectral bandwidth > 16 nm at 20 dBc, a comb line optical power > 650 nW (at 20 dBc), a pulse repetition rate of 3.4 GHz, and an RF linewidth of the free-running pulse repetition rate < 10 kHz. To realize a proof-of-concept demonstrator module, the diode laser-based OFCG was hybrid-integrated into a space-suitable technology platform that has been developed for future QUANTUS experiments. Proof of sufficient RF stability of the OFCG was provided by stabilizing the pulse repetition rate to an external RF reference. This resulted in a stabilized pulse repetition rate with an RF linewidth smaller than 1.4 Hz (resolution limited), thus exceeding the requirement. The developed diode laser-based OFCG represents an important step towards an improved comparison of the rate of free fall of Rb and K quantum gases within the QUANTUS experiments in micro-gravity.
A deep ultraviolet laser light source by frequency doubling of GaN based external cavity diode laser radiation
A deep ultraviolet laser light source by frequency doubling of GaN based external cavity diode laser radiation - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook A deep ultraviolet laser light source by frequency doubling of GaN based external cavity diode laser radiation write by Norman Ruhnke. This book was released on 2022-05-13. A deep ultraviolet laser light source by frequency doubling of GaN based external cavity diode laser radiation available in PDF, EPUB and Kindle. A compact and portable laser light source emitting in the wavelength range between 210 nm and 230 nm would enable numerous applications outside of laboratory environments, such as sterilization and disinfection of medical equipment, water purification or gas and air analysis using absorption spectroscopy. Such a source is also highly attractive for the identification and quantification of proteins and biomolecules by means of laser-induced fluorescence or Raman spectroscopy. In this thesis, a novel concept to realize such a compact and portable laser light source with low power consumption and an emission around 222 nm is investigated. The developed concept is based on single-pass frequency doubling of a commercially available high-power GaN laser diode emitting in the blue spectral range. Due to the low frequency doubling conversion efficiencies in this wavelength range of about 10-4 W-1, a laser diode with high optical output power above 1 W is required as pump source. Moreover, it has to exhibit narrowband emission in the range of the acceptance bandwidth of the applied nonlinear BBO crystal. Since GaN-based high-power laser diodes typically show broad emission spectra of Δλ = 1…2 nm, stabilizing and narrowing their wavelength by using external wavelength-selective elements is investigated and presented for the first time. With the understanding for the novel concept gained in this work, a compact ultraviolet laser light source was realized. It has a power consumption of less than 10 W and is exceptionally robust due to its immoveable components. The demonstrated output power of 160 μW enables numerous industrial and everyday applications for which previous laser systems have been too complex and overly cost- and energy-intensive.
Epitaxial Design Optimizations for Increased Efficiency in GaAs-Based High Power Diode Lasers
Epitaxial Design Optimizations for Increased Efficiency in GaAs-Based High Power Diode Lasers - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Epitaxial Design Optimizations for Increased Efficiency in GaAs-Based High Power Diode Lasers write by Thorben Kaul. This book was released on 2021-04-09. Epitaxial Design Optimizations for Increased Efficiency in GaAs-Based High Power Diode Lasers available in PDF, EPUB and Kindle. 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.
