Dynamics of 1.3(mu)M semiconductor lasers and nonlinear gain /
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1990.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | Optical modulation is used for the first time to determine the intrinsic frequency response of a laser diode. The measured frequency response does not have the undesirable signal rolloff caused by diode parasitics that occurs with direct RF current modulation. The ability to obtain parasitic-free data creates new opportunities for studying the dynamics of semiconductor lasers. Using the optical modulation technique, the origin of nonlinear gain in 1.3 μm InGaAsP semiconductor diode lasers was studied by measuring the magnitude and phase of the laser's intrinsic frequency response. The measured results indicate that a dielectric grating induced by stimulated emission in the laser cavity is important in determining the nonlinear gain. Since physical processes such as spectral hole burning, hot carriers, etc., are all induced by stimulated emission, it is not possible by this experiment alone to determine the process which is responsible for the dielectric grating. However, by comparison of the measured modulation K-factors (the ratio of the damping factor γ to the square of the resonance frequency f^2[0]) of distributed feedback and Fabry-Perot lasers, we found that the relaxation time associated with nonlinear gain for 1.3μm InGaAsP semiconductor laser is about 0.1 ps. This short time constant indicates that spectral hole burning is the dominant process responsible for the stimulated emission induced dielectric grating, which causes the nonlinear gain. Using this technique, the rate of spontaneous emission into the guided modes, the nonlinear gain coefficient, and the carrier lifetime at lasing threshold are measured to unprecedented accuracy. These results are used in other work for understanding the noise properties of diode lasers. In addition, the modulation K-factor is shown for the first time to depend on the doping level for semiconductor lasers. This finding has important implication with regard to the issue of the upper modulation bandwidth of semiconductor lasers. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Electrical engineering." |
| Physical Description: | xii, 82 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |