Investigation on the frequency stabilization of laser diode

实验证明，相位-振幅噪声转换和滤波光反馈技术可以有效地抑制外腔半导体激光器（ECDL）的过量相位噪声。我们已经观察到，使用上述技术，ECDL的相位噪声被抑制超过40 dB，并达到15 MHz的散粒噪声极限。这为降低半导体激光器的相位噪声开辟了一条新的途径。我们利用增强腔产生了二次谐波光。这允许25%的转换效率，并在540 nm处产生高达10 mW的输出功率。

We experimentally demonstrated that the excess phase noise of an external cavity diode laser (ECDL) can be efficiently suppressed by phase-to-amplitude noise conversion and filtered optical feedback techniques. We have observed that the phase noise of an ECDL was suppressed more than 40 dB and reached the shot noise limit from 15MHz using the above-mentioned technique. This opens a new way to reduce the phase noise of diode lasers. We generated second harmonic light using a enhancement cavity. This allows an conversion efficiency of 25% and produces an output power of up to 10 mW at 540 nm.