| Summary: | 碩士 === 國立交通大學 === 光電工程系所 === 97 === In this thesis, we investigated the different lasing behavior of GaN-based 2D photonic crystal surface emitting lasers (PCSELs) according to different photonic crystal (PhCs) lattice constant. Based on the Bragg theory for PhCs period structure, the lasing behavior could only happen when the Bragg condition is satisfied. Therefore, we simulated the band diagram of TE mode by plane wave expansion method, designed the PhCs lattice constant ranging from 190 to 230 nm, and fabricated the PhCs period structure on our novel GaN-based resonance cavity light emitting diode. By the excitation of pulse laser, the PhCs lasing action is achieved under the optical pumping system. Normalized frequency of investigated PCSELs lasing wavelength can be correspond to three band-edge frequencies (Γ1, K2, M3), which indicates the lasing action can only occur at specific band-edges. We also measured the angle-resolved μ-PL diagrams of different lasing modes. The results further confirmed the lasing modes existed at different band-edge (Γ1, K2, M3) and emitted different lasing angles by mapping the diffraction patterns of band structures and the Bragg theory. From our experiment results, the three band-edge frequencies including Γ1, K2, and M3 has different emission angles corresponding to the normal direction (0˚, 29˚, 59.5˚), respectively. Moreover, the far field pattern of Γ1 mode we observed is symmetric due to the PhCs’ symmetric pattern structure. Besides, the degree of polarizations and divergence angles of Γ1, K2, and M3 modes laser are about (33%, 35%, 55%) and (1.2˚, 2.5˚, 2.2˚), respectively. Overall, according to the superiority features of GaN-based PCSELs, the structure can be applied in the visible and UV laser and become the highly potential optoelectronic device in high power emitter applications.
|
|---|
