טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentSkorka Orit
SubjectIntegrated Optics in GaN
DepartmentDepartment of Electrical Engineering
Supervisor Professor Emeritus Yosef Salzman


Abstract

The wide-band-gap III-V compound semiconductor material system is a subject for much attention in recent years. The increase in interest in the AlGaInN family of materials has been fueled by optical applications - LEDs, LDs and UV detectors. The purpose of this work is to study optical guided-wave propagation in GaN-based structures and the effect of the specific material properties on guided-wave phenomenon.

The first part of this work presents a model for the typical structure of the GaN-based laser diode. The purpose of this model is to suggest an explanation for the side lobes, which characterized the output spectrum of GaN lasers grown on sapphire substrates. This model regards the laser structure as combined of two light guiding coupled layers, i.e. two parallel coupled waveguides. Grain boundaries in the buffer layer are being regarded as low reflectance internal mirrors, which add longitudinal coupling to the system. Based on the suggested model, a simulation results in a spectrum, which is in very good agreement with the measured spectra.

The second part of this work presents GaN-based multimode waveguides, which were grown and fabricated in our laboratories. The optical losses of a series of different width GaN waveguides were measured in blue light wavelength (488nm) using the out-scattering technique. The measurement results led us to the calculation of the internal optical losses of a GaN multimode layer. The optical losses of a waveguide partially covered with a metal layer were also measured.