| Summary: | 博士 === 國立交通大學 === 光電工程所 === 87 === In this dissertation, we fabricate high spontaneous emission factor semiconductor microcavity lasers and study their lasing properties such as the resonant wavelength, spontaneous emission factors, and far-field emission distributions. We also succeed on extending the operation wavelength region of these microcavity lasers from 1.5 mm to 0.66 mm. Interesting mode competition is observed for larger cavity volume lasers while the cavity volume is only a few times of cubic wavelength, single mode lasing can be achieved. We develop a method to deduce the spontaneous emission factor b from the experimental light output versus pumping intensity curves based on a single-mode rate equation analysis. Comparison of the b values for microcavities with different cavity volumes clearly indicates b is inversely proportional to the cavity volume.
Here we follow the conventional (r,f,q) notation in the cylindrical coordinate. We find that the far-field emission in the q direction for microdisk and microring laser has a narrow Gaussian distribution and the FWHM of the angular spread qFWHM is much smaller than that of a planar source with the same thickness. Based on a scalar diffraction theory in the cylindrical coordinate, an analytic expression for qFWHM is derived. The results exhibit an additional Hankel function factor difference when compared with the case of a planar boundary. This factor narrows the angle spreading in the q direction and is a function of the disk diameter. On the other hand, the far-field emission in the f direction shows a m-peaks quasi-periodic distribution around the circumference, where m is the azimuthal index. The polarization of emission is linearly polarized along the f direction from measurement.
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