Correlation Domain Spectroscopy by Frequency-Chirped Light

在这项研究中，一种新的光谱技术--相关域光谱作为移频反馈激光器的一种应用进行了研究。主要研究成果如下：1.研究成果。相关域光谱学、理论和实验。对用连续波光测量样品的脉冲响应进行了理论分析。这项技术被命名为相关域谱学。为了演示相关域光谱，由于激光输出的频率啁啾是高度线性的，因此采用移频反馈激光器作为频率啁啾光源。在实验中，测量了光纤环路的脉冲响应。我们成功地测量了脉冲响应，时间分辨率为5 ns。由于该技术使用的是连续波光，因此有可能测量光学损伤阈值较低的材料，如生物样品。光纤色散的测量一种以掺铒光纤为增益介质的移频反馈激光器。该激光器的优点是波长可调范围宽。通过改变腔内声光调制器的驱动频率对波长进行调谐，获得了10 nm的调谐范围。另一个优点是激光器的振荡频率为1.55μm，这是光通信的波长。结合这些优点，我们提出并演示了利用移频反馈激光器测量光纤的群速度色散和偏振模色散。在实验中，分别以0.1ps/nm/km和0.01ps的分辨率测量了群速度色散和偏振模色散。

In this research, a new technique in spectroscopy ; correlation domain spectroscopy was studied as an application of a frequency-shifted feedback laser. The main outcomes of the research are following.1. Correlation domain spectroscopy, theory and experiment.A theoretical analysis is developed for a measurement of a impulse response of a sample by a continuous wave light. The technique was named the correlation domain spectroscopy. To demonstrate the correlation domain spectroscopy, a frequency-shifted feedback laser was used as a frequency-chirped light source, because the frequency-chirp of the laser output is highly linear. In the experiment, an impulse response of an optical fiber loop was measured. We succeeded to measure the impulse response with a temporal resolution of 5 ns. Since the technique uses the continuos wave light, it is possible to measure the materials with low optical damage threshold such as biological samples.2. Measurement of dispersion of optical fiberA frequency-shifted feedback laser with an erbium doped fiber as a gain medium. The advantage of the laser is a wide wavelength tunable range. The wavelength was tuned by varying the driving frequency of the intracavity acoustooptic modulator, and 10 nm tuning range was obtained. The another advantage is that the laser oscillates at 1.55 μm which is the wavelength of the optical communication. Combining these advantages, we have proposed and demonstrated a measurement of the group velocity dispersion and polarization mode dispersion of an optical fiber by use of the frequency-shifted feedback laser. In the experiment, the group velocity dispersion and the polarization mode dispersion were measured with resolutions of 0.1 ps/nm/km and 0.01 ps, respectively.