Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 24 for “"single mode operation"”.
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Vertical -Cavity Surface -Emitting Lasers Operating in Photonic Crystal Waveguide Defect Modes
Single mode operation in vertical cavity surface-emitting lasers is important for sensing and communications applications. A comprehensive study of the use of a periodic array of etched circular holes in the top distributed Bragg reflector of a vertical cavity surface-emitting laser to achieve …
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Modeling of Vertical -Cavity Surface -Emitting Lasers and Comparison With Experiment
It is shown that the multimode behavior can be controlled by changing the relative sizes of the current confinement aperture and the index-guide aperture. This is true even in the limit of devices with very large apertures, for which the cold-cavity resonant wave-lengths and losses are the same for …
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Designs for Zero Polarization-Mode Dispersion And Polarization-Maintaining Fibers
… over long lengths, provide zero polarization-mode dispersion, and function as polarizers or mode filters are presented. First, optimum designs for high-birefringence as well as single-polarization single-mode fibers are studied. For high-birefringence fibers, several index profiles were …
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Controlled Lasing in Gallium Nitride Nanowires
… is a semiconductor-nanowire laser, where a single, monolithic nanowire functions simultaneously as an optical microcavity and active medium, leading to an extremely compact and robust laser. Recent advances in nanowire synthesis have enabled realization of optically pumped nanowire lasers in …
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Bending losses in large mode area holey fibres
… potential offered by holey fibres in the large-mode-area, single-mode regime, and to place their performance in context against conventional step-index fibres. In the study presented here, numerical and experimental techniques have been developed that are capable of accurately evaluating the …
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Development of high speed vertical cavity surface-emitting semiconductor diode laser and transistor laser
… to show a high modulation bandwidth as well as single-mode operation; however, because of the small oxide aperture (< 3 µm), a microcavity VCSEL shows high resistance and low optical power. An 850 nm oxide-confined VCSEL with an aperture ~4 µm is able to show error-free transmission at 40 Gb/s. …
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Tools for quantum optics : pulsed polarization-maintaining Er-doped fiber laser and spatial mode manipulation in spontaneous parametric downconversion
… for quantum optics. In one project, a pulsed, mode-locked erbium-doped fiber laser, designed to be used as a seed laser for a 390 nm source, was built using polarization-maintaining components to address polarization drift. The fiber laser operated at a center wavelength of 1560.0 nm with an …
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High power pulse UV source development and its applications
… The system includes four critical components: a single mode Nd:YAG oscillator, 6-stage amplifier chain, a pulse compressor and frequency conversion units. We optimized each component for maximum energy throughput with an emphasis on stability and reproducibility. At each stage, the optical output …
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Transverse mode selection and brightness enhancement in laser resonators by means of volume Bragg gratings
The design of high power lasers requires large mode areas to overcome various intensity driven nonlinear effects. Increasing the aperture size within the laser can overcome these effects, but typically result in multi-transverse mode output and reduced beam quality, limiting the brightness of the …
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Monolithic integration of semiconductor ring lasers
… as ultrafast directional bistability, stable single mode operation and potential for integration. However, most of the mode dynamical behavior as well as the optimum device design are still far from a complete understanding. This thesis reports on the design, technological development and …
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Design of a 250 GHz gyrotron amplifier
… band gap (PBG) interaction circuit for stable single mode operation in an overmoded circuit. The design mode is a TE03-like mode confined by the PBG lattice with no nearby competing modes. The design of the input coupler, interaction circuit, output coupler and electron gun have also been …
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Ultrashort, High Power, And Ultralow Noise Mode-locked Optical Pulse Generation Using Quantum-dot Semiconductor Lasers
… generation based on active, passive, and hybrid mode-locked quantum dot semiconductor lasers with target applications such as optical interconnect and high speed signal processing. Design guidelines are developed for the single mode operation with suppressed reflection from waveguide …
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COHERENCE AND FREQUENCY STABILITY OF SEMICONDUCTOR LASERS UNDER CW OPERA TI ON AND MODULATION
… semiconductor lasers. A computer simulation model of a semiconductor laser is then presented to investigate the effects of inhomogeneous broadening on the (longitudinal) mode stability of the laser. In particular, the model developed here enables the electronic intraband relaxation scattering …
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Modelling and experimental investigation of Structured Optical Fibres: Optimisation of drawing conditions
… many new features such as significantly extended single-mode regime. The design and fabrication of SOFs with desirable optical properties are essential for their applications in modern telecommunications and networking, smart sensing, and material processing. The main objective of this study is to …
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Parity-time and supersymmetry in optics
… breaking offers a new method for achieving single mode operation in laser cavities. Other interesting phenomena also arise in connection with PT periodic structures. Along these lines, we introduce a new class of optical lattices, the so called mesh lattices. Such arrays provide an ideal …
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Materials science and design for germanium monolithic light source on silicon
… Si waveguides for a low threshold current and single mode operation. Heavy n-type doping was observed to change the Ge electronic band structure by band gap narrowing effect. We also found a failure of using a simple Drude model to explain free carrier absorption in n-Ge. We modified the …
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Automated wavelength recovery for silicon photonics
… is the lack of ability to enable more than a single channel on a single wire/fiber. Silicon photonics, offering a solution on the same platform with CMOS technology, can enable Wavelength Division Multiplexed (WDM) systems. However, Silicon photonics has to overcome the wafer level, …
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Development of tunable terahertz quantum cascade wire lasers
… cross-section results in a large fraction of mode propagating outside of the laser core (GaAs/A1₀.₁₅Ga₀.₈₅As material system). The frequency tuning is achieved by changing the transverse wave vector, using a plunger made by metal (metal plunger) or silicon (dielectric plunger). When nudged …
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High-average-power planar waveguide lasers
… structure allows diode pumping at its multimode broad channel end and ensures fundamental-mode laser output at the single-mode channel end, with adiabatic operation achievable through careful design of the interconnecting taper. Linear and parabolic taper shapes are compared. The two types …
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Experimental study of a high efficiency step-tunable MW gyrotron oscillator
… at MW power levels and whose initial 110 GHz operation was expanded to include operation at 124.5 GHz. To this end, a new set of components, including a cavity, mode converter, and output window were designed for operation at both frequencies. The cavity was designed using the code MAGY and …
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