<p>Since the inception of integrated electronic circuits there has been a trend of miniaturizing as many electronic, optical and even mechanical circuits and systems as possible. For optical applications this naturally led to the invention of semiconductor optical sources such as the laser diode (LD) and the light emitting diode (LED). A third device, the superluminescent diode was later invented to offer an output with a power similar to that of an LD and spectral width similar to that of an LED. However, there is usually a trade off between the output power and spectral width of the generated beam. The main challenge in the development of SLD is, therefore, finding ways to mitigate the power-spectral linewidth trade off.</p> <p>Previous work has two major directions. In the first one the goal is to eliminate facet reflections thus preventing lasing from happening. The detrimental effect of lasing is that even before it starts the spectral width quickly narrows down. In the second research direction the goal is to make the material gain spectrum wider by playing with different parameters of quantum well active regions.</p> <p>This research work explores yet another way of broadening output spectrum of SLD while allowing the power to increase at the same time. The surface-plasmon waveguide (SPWG) has been proposed to replace the dielectric waveguide, for the first time. A novel SPWG structure is introduced and designed to optimize the device performance in terms of the output power, spectral width and their product known as the power-linewidth product. The effect of different parameters of the new structure on the output light is investigated and attention is given to the high power, high spectral width and high power-linewidth product regimes.</p> / Doctor of Philosophy (PhD)

This Master's thesis discusses about the measurement of the carbon dioxide concentration in breathing by an optical analyzer using infrared absorption spectroscopy. The method is described with the technical focus on individual components needed for subsequent implementation. A circuit diagram is created to produce Arduino platform devices that serve as hardware to connect and power individual parts and software to create a user environment, followed by a Bluetooth module to transmit measured data to mobile devices where real-time results are presented.