Thin Film Lasers Integrated with Planar Waveguides
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This dissertation describes the fabrication and integration of a thin film edge emitting laser (EEL) whose optical output is coupled into a polymer waveguide integrated onto the same electrical interconnection substrate. This embedded laser/waveguide structure is a fundamental building block toward the realization of planar lightwave circuits using embedded optical interconnections. The demonstration of a thin film laser integrated with a planar waveguide eliminates the need for either an external optical source coupled to the waveguide or a bump bonded optical source with a beam turning element to turn an optical beam into the waveguide. In this work, the wedge-induced facet cleaving (WFC) method is adapted to fabricate the thin film EELs. Bisbenzocyclobutene (BCB) polymers are used to fabricate channel waveguides, and thin film lasers are integrated with the polymer waveguides. The coupling efficiency from the laser to the polymer waveguide is estimated through measurement and theoretically calculated. In the theoretical calculation, the thin film transfer matrix method is used to analyze the optical modes in the semiconductor cavity. The coupling efficiency from the laser to the polymer waveguide is analyzed using a finite element method (FEM), and are then compared to the experimental results. The experimentally estimated coupling efficiency is in good agreement with that of the theoretical calculation. In addition, the relationship between threshold current, output power, and facet reflectivity of the thin film laser is analyzed using FEM.