| Summary: | 碩士 === 國立高雄師範大學 === 物理學系 === 87 === The purpose of this thesis is to present the pump probe system with femto-second pulse laser and employ the measurement of the gain dynamics of GaAs Single Quantum Well Semiconductor Laser Amplifiers (SQW SLA). The femto-second pulse laser is a wavelength tunable (730~850nm) Ti:sapphire laser. The pumping source is a quasi single-frequency (632nm in wavelength) Nd:YVO4 laser. By using the auto-correlator and optical spectrum analyzer we can verify that the pulse is unchirped with pulsewidth of 110 fs, and spectrum width of 10 nm. Our sample is a SQW GaAs SLA with 5° striped angle, double hetero-junction structure. The thickness of the active layer is 0.08μm. The SLA is highly polarization dependent. The transparent current is about 25mA and the gain is 25dB at 100mA.With pump probe technique, I have built up the experiment system for SQW SLA. The features of the system include: the femto-second resolving ability, the tunable power and polarization of pump beam and probe beam, the expandability of different samples and the ability to co-operate with the computerized instrument control and data acquisition system. Base on our experiment data, the changes of the gain dynamics may be resolved into two parts. The first part is a slow recovering term and its time constant is much bigger than 10ps. The second part is a fast recovering term and its time constant is about 580fs. The possible corresponding explanation is that the slow recovering term is duo to carrier depletion effect and the fast recovering term may be dominates by carrier heating effect.
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