Study of the excess noise associated with demodulation of ultra-short infrared pulses
Study of the excess noise associated with demodulation of ultra-short infrared pulses
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DOI：
10.1109/tuffc.2005.1503992
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发表时间：
2005-07-01
影响因子：
3.6
通讯作者：
Hollberg, L
中科院分区：
文献类型：
--
作者：
Ivanov, EN;Diddams, SA;Hollberg, L
使用光电探测器解调超短光脉冲会伴随脉冲重复率处的过量相位噪声以及光电流频谱中的谐波。造成这种噪声的主要因素是检测到的脉冲串的功率波动，如果不进行补偿，会严重限制从光域到微波域的频率传输的稳定性。通过使用红外飞秒激光器，我们测量了多余相位噪声的谱密度，以及不同类型的 InGaAs 光电探测器的功率到相位转换。噪声测量是通过使用光纤耦合分束器的新型双通道读出系统进行的。当飞秒脉冲序列的平均功率稳定时，在测量系统的两个通道中都观察到了对过量相位噪声的强烈抑制。这项研究的结果对于开发源自光学“时钟”和光学频率合成的低噪声微波源具有重要意义。
The demodulation of ultra-short light pulses with photodetectors is accompanied by excess phase noise at the pulse repetition rate and harmonics in the spectrum of the photocurrent. The major contribution to this noise is power fluctuations of the detected pulse train that, if not compensated for, can seriously limit the stability of frequency transfer from optical to microwave domain.By making use of an infrared femtosecond laser, we measured the spectral density of the excess phase noise, as well as power-to-phase conversion for different types of InGaAs photodetectors. Noise measurements were performed with a novel type of dual-channel readout system using a fiber coupled beam splitter. Strong suppression of the excess phase noise was observed in both channels of the measurement system when the average power of the femtosecond pulse train was stabilized.The results of this study are important for the development of low-noise microwave sources derived from optical "clocks" and optical frequency synthesis.