DEVELOPMENT OF A COMPACT AND EFFICIENT BLUE-RAY LASER DIODE LIGHT SOURCE

本研究项目首次对65 mW、405 nm紫光激光二极管的噪声特性进行了分析，并将其频率起伏稳定到了超相干水平。我们测量了一些工作条件下的纵模行为，包括环境温度和光反馈量等。对于典型的光学拾取系统中常见的一些光反馈量，我们已经证实了平均相对强度噪声(RIN)值高达-125分贝/赫兹，而RIN的外腔长度依赖关系在外腔长度与样品LD的有效内腔长度的整数倍重合的某些点上反复呈现出最大和最小的尖峰。在这种情况下，我们通过选择反馈光的偏振，实现了将光反馈噪声抑制在-132dB/Hz左右。此外，我们还证明了被测的65 mW、405 nm紫光激光二极管样品有多模振荡的倾向，因此应在环境温度控制在15℃左右时进行单纵模工作。因此，我们最终利用基于Pound-Drever-Hall方法的参考法布里-珀罗腔实现了紫光激光二极管的稳频。结果首次实现了400 nm紫光半导体激光器的频率稳定度为3.46×10~(-11)~(-11)的最小阿仑方差。

This research project has demonstrated for the first time the analysis of noise properties in a 65mW, 405nm violet laser diode and also stabilized its frequency fluctuations as low as hyper coherent level. We measured the longitudinal mode behavior in some operation conditions, including the ambient temperature and optical feedback amount and so on. With some optical feedback amounts usually seen in typical optical pick-up systems, we have confirmed that the average relative intensity noise (RIN) value measures up to about-125dB/Hz, while the external cavity length dependences of the RIN show maximal and minimal spikes repeatedly at certain points where the external cavity length coincides with integral multiples of the effective internal cavity length of our sample LD. Under such circumstances, we have achieved the suppression of the optical feedback noise to about-132dB/Hz by selecting the polarization of the feedback light. Moreover, we have proved the measured 65mW, 405nm violet laser diode sample tends to oscillate in multiple modes, so that we should carry out the single longitudinal mode operation by controlling the ambient temperature about 15℃. Thus, we have finally attained the frequency stabilization of the violet laser diode using a reference Fabry-Perrot cavity based on the Pound-Drever-Hall method. As a result, we have achieved for the first time the frequency stability of 3.46x 10^<-11> of the minimum square root of Allan variance in a 400nm type violet laser diode.