Relative Intensity Noise (RIN) of multiple quantum well (MQW) DFB laser and chirped multilayer quantum dot (CMQD) lasers have been measured and analyzed. The carrier dynamics in multilayer quantum structure are therefore determined.
The temperature-dependent RIN measurement of MQW DFB laser was undertaken to evaluate the K-factor and differential gain. Carrier transport is limited by multiple layer structure in the DFB laser as the values of K-factor remain almost constant at 0.33 ns in the temperature range of 10 - 40 ℃.
Therefore, the intrinsic maximum modulation bandwidth ( fmax ) is evaluated to be 27 GHz. However, differential gain reflects the nature of gain spectrum broadening which decreases by a factor of approximately 1.5 (from 1.66×10-15 cm2 down to 1.1×10-15 cm2) over the measured temperature range.
The RIN measurement is limited for short cavity lasers as modes contribute to partition noise that average out the power fluctuation. In general, cavity length for RIN measurement is suggested to be within 2 mm. The characteristics of chirped multilayer quantum dot (CMQD) lasers has been presented with different cavity lengths of 750 μm, 1000 μm, and 1500 μm at ambient temperature of 20 ℃. For cavity length of 750 μm, the highly damped RIN spectra have calibrated level of -160dB/Hz, which consist with the literature. In addition, excited state lasing is essential in our device in order to overcome the total loss and therefore reaches the lasing condition.
The differential gain is estimated to be in the range of 3.0-8.210-16 cm2, which is subject to junction heating in as-cleaved devices. However, the K-factor limited bandwidth (fmax), which is temperature insensitive, is as
large as 14 GHz, shows excellent agreement with Stevens et al., who firstly demonstrated direct modulation of excited state QD lasers in August 2009. To the best of our knowledge, we have successfully demonstrated RIN spectrum of excited state quantum dot lasers for the first time.
Another unexpected observation is the double-resonance RIN spectra in even shorter cavity length of 600 μm. However, the mechanism is still a controversial issue. Therefore, this thesis has thrown up some questions for further investigation.
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簡歷(Vita)
姓名：湯皓玲 (Hao-Ling Tang) 性別：女
出生年月日：民國 74 年 8 月 27 日 學歷：
國立中正大學物理系學士 (92.9~96.6)
國立交通大學電子研究所碩士班 (96.9~98.9)
碩士論文題目：
半導體量子結構雷射元件之相對雜訊強度研究
Study on Relative Intensity Noise of Semiconductor Quantum Structure Lasers