| Summary: | 碩士 === 國立交通大學 === 光電工程系所 === 97 === A new laser structure consisting of quantum dots (QDs) as the active medium and gold-coated metallic waveguide, designed and fabricated by Professor Chuang’s group (Chien-Yao Lu) at the University of Illinois, is studied. The structure design and the fabrication of this device are introduced, and the lasing action is also observed. Both theoretical analysis and experimental measurements are performed on the optical characteristics of the QD plasmonic laser. The amplified spontaneous emission (ASE) measurements of a QD plasmonic FP laser emitting in the 1287 nm wavelength region are investigated. Our experimental study of the ASE spectra under different injection currents includes both continuous wave (CW) and pulsed mode bias conditions. From the ASE spectra, we can extract the net modal gain, the refractive index change, the linewidth enhancement factor, and the group index. Our experimental analysis reveals a low linewidth enhancement factor of about 0.35 at the lasing wavelength, which is helpful for high-speed operation, reduced filamentation, self-focusing, anti-guidance in broad-area emitters, and reduced chirp under modulation. Furthermore, we observed an infinite characteristic temperature T0, in the range of 7 to 15oC, indicating completely temperature-insensitive operation is possible. The observed high group index in the QD plasmonic FP laser indicates that the sidewall-coated metal layers contribute to the dispersion of the waveguide guiding mechanism. Our experimental results show that the metallic sidewall-coated QD plasmonic FP laser is a promising device with symmetric gain, reduced linewidth enhancement factor, high temperature stability, which has considerable potential for future high-speed reduced-chirp operation, and helpful for plasmonic nanolaser studies.
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