<p> Compositionally asymmetric multiple quantum well (AMQW) lasers are used for the demonstration of the gain flattening coating functionality. The gain spectra of the lasers are extracted using a non-linear least square fitting method. An optimum facet reflectance spectrum is calculated for a chosen current. For manufacturability, a modified reflectance spectrum of the gain flattening coating is proposed, in order to achieve operation over a wider spectral range without the 'difficult' gap which was a region where lasing was difficult or impossible to achieve due to insufficient gains at these wavelengths. </p> <p> Silicon oxides films with high, medium, and low refractive indices fabricated in an inductively coupled plasma (ICP) enhanced chemical vapor deposition (CVD) system are chosen as the building blocks of the gain flattening coating. An 18-layer coating is designed by the insertion of needle-like refractive index variation with a few optimization methods applied to minimize the merit function. A laser bar holder is custom designed and fabricated. Experiments and modification on the laser bar holder are carried out for better performance. The 18-layer gain flattening coating is then fabricated in the ICPCVD system with an in-situ spectroscopic ellipsometric measurement. It is observed that the non-lasing gap has disappeared after the coating is applied. Without external feedback, the coated laser shows tuning over 85 nm with the central wavelength of 1593 nm, while the uncoated laser has a non-lasing gap of about 25 nm in the central region of the tuning range of 70 nm. </p> <p> Finally, the coherence length of a low coherent source synthesized from the gain flattening coated AMQW laser is measured by using Michelson interferometer. The highest depth resolution that can be achieved is measured as 40 μm. The power intensity of the synthesized low coherence light source from the gain flattening coated AMQW laser is rendered from the interferogram using fast Fourier transform (FFT). </p> / Thesis / Doctor of Philosophy (PhD)

The main objective of this research is to fabricate and characterize an optically integrated interferometric sensor on standard silicon and silicon CMOS circuitry. An optical sensor system of this nature would provide the high sensitivity and immunity to electromagnetic interference found in interferometric based sensors in a lightweight, compact package capable of being deployed in a multitude of situations inappropriate for standard sensor configurations. There are several challenges involved in implementing this system. These include the development of a suitable optical emitter for the sensor system, the interface between the various optically embedded components, and the compatibility of the Si CMOS with heterogeneous integration techniques. The research reported outlines a process for integrating an integrated sensor on Si CMOS circuitry using CMOS compatible materials, integration techniques, and emitter components.