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Electrical and Optical Characteristics of Semiconductor Lasers Using Differential Resistance Measurements
Hongyi Mi
Date: 2008-03-26
Degree: MS - Electrical Engineering
Advisory Committee
Doug Barlage - Committee MemberRobert M Kolbas - Committee Chair
W. Rhett Davis - Committee Member
Abstract
The motivation of this work is exploring the characteristics of electrical and optical derivatives in semiconductor laser diodes at different temperatures using current modulation. Electrical and optical derivatives (V-I, L-I, dV/dI, dL/dI) at low temperatures are investigated and compared with that at room temperature. The information from V-I, L-I, dV/dI, d2V/dI2, dL/dI is used to detect series resistance, laser threshold, Quasi Fermi level locking, quantum efficiency, current ideality and light ideality. Different methods of calculating the laser threshold, series resistance, ideality and quantum efficiency by plotting appropriate curves have been identified. This approach is shown good to determine the optimal method to determine the laser threshold value through comparison of four different methods plots of V-I, dV/dI and L/(dL/dI). The kink at laser threshold of dV/dI curve gives information of series resistance change of laser diode. As temperature decreases from room temperature to 77K, an anomalous phenomena happens to the kink, which is that the kink varies from downward to flat, and then to upward. The value of laser threshold also decreases as temperature decreases. Thus, we can show the temperature dependence of laser threshold for laser diode to some extent.
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