本論文以銣原子氣體進行階梯式電磁誘發透明實驗，並觀測銣原子同位素87Rb，在激發態5D5/2、9S1/2的超精細結構。當弱光的探測雷射波長為780.2 nm (5S1/2→5P3/2的共振頻率)通過Rb蒸氣分子時會被吸收，但是如果同時有另一強光的耦合雷射波長為776 nm (5P3/2→5D5/2)，或565 nm (5P3/2→9S1/2)的存在時，則會發生探測雷射的穿透現象。此為探測雷射及耦合雷射皆達到銣原子能階躍遷頻率，產生原子波函數的量子干涉的結果，稱之為電磁誘發透明。實驗使用探測雷射與耦合雷射反向對打，並且在銣原子蒸汽樣本中使之重合，銣原子同時受到兩種不同頻率的光場作用。其中，探測雷射的頻率鎖定在銣原子D2 躍遷的超精細結構譜線上，而耦合雷射則在銣原子高能態的躍遷頻率附近進行掃描，藉以研究其超精細結構。藉由觀察探測雷射的穿透強度變化，以及受激發原子自發衰變的螢光訊號，可以量測銣原子的階梯式電磁誘發透明的能譜，並將實驗結果與模擬計算做比較，目前實驗結果的訊噪比還不足以有效分析87Rb (5D5/2、9S1/2)的超精細結構。

The hyperfine structure of 87Rb 9S1/2 and 5D5/2 states was investigated using cascade-type electromagnetically induced transparency (EIT) in this thesis. The theoretical modeling the transparency of a weak probe laser beam at 780.2 nm (5S1/2→5P3/2) under the interaction with a strong coupling laser beams at 565 nm or 776 nm (5P3/2→9S1/2 or 5P3/2→5D5/2) was obtained by solving the steady state solutions of optical-Bloch equations. This transparency is due to the quantum interference of the atomic wavefunctions under the photon-atom interactions. To carry out the experiment, a probe laser and a coupling laser are counter-propagated, overlapped inside the rubidium vapor cell. The frequency of probe laser was stabilized at D2 line hyperfine transitions of 87Rb and the coupling laser scanned across the transitions of excited states to investigate their hyperfine structure. The EIT and laser induced fluorescence spectrum of rubidium atom were detected by measuring the transmission of the probe laser or fluorescence from the excited atoms. The simulation result agrees well with the experimental spectra. However, there is no further hyperfine results can be made due to bad signal to noise ratio.

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