本論文研究具有布拉格洋蔥狀結構之膽固醇液晶微球於光渦流光鉗光束操控下之軌道轉動特性。實驗結果顯示，膽固醇液晶微球之軌道轉動速率由來自兩方面之軌道角動量貢獻所決定: 一為光渦流光鉗光束所擁有的軌道角動量直接轉移給微球的直接軌道角動量(以ld表徵)，二為光渦流光鉗之圓偏振分量經過具有等效q-plate效能之微球後間接轉移給微球的間接軌道角動量(以lind表徵)；此間接軌道角動量之轉移，乃因為膽固醇液晶微球在垂直於入射光之中央切面上的液晶排列結構可等效為q = 1的q-plate，當光渦流光鉗之圓偏振分量經過此q-plate-like微球後得到的軌道角動量也會反轉移給微球同大小但反轉向之軌道角動量，就是此間接軌道角動量會產生微球自我引致軌道轉動現象。
如上所述，微球獲得的直接和間接角動量大小會因不同實驗條件而有所不同，為有條理地定性探討上述條件對膽固醇液晶微球之軌道轉動速率之影響，本論文研究分成三部分。第一部份先觀察與紀錄膽固醇液晶微球受圓偏振綠光雷射(波長為532 nm)光鉗作用下所產生的自引致軌道轉動，可以間接轉移給微球的lind在不同條件下之差異性定性加以解釋；第二與第三部份分別觀察與紀錄反射波段涵蓋與不涵蓋光渦流光鉗波長之微球，在光渦流光鉗(l = -8)照射下之軌道轉動行為，可以直接和間接轉移給微球的ld與lind在不同條件下之差異性定性加以解釋。以上三部份的實驗結果顯示，藉由改變光渦流光鉗所具有的圓偏振旋性與膽固醇液晶微球之旋性與反射波段等條件，可產生不同程度之角動量轉移(從光鉗轉至微球)，最後得到微球不同的軌道轉動行為。

This thesis aims to study the orbital rotation of cholesteric liquid crystal microdroplets (CLC MDs) with Bragg-onion structure under manipulation of an optical vortex tweezers (OVTs) beam. Experimental results show that the angular speed for the orbital rotation of the CLC MDs can be determined by the contributions of two orbital angular momenta (OAM) to the MDs. One is the direct OAM which is directly transferred from the OVTs to the MDs, another the indirect OAM which is indirectly transferred from the circular component of the OVTs to the MDs through the q-plate-like MDs (characterized by the direct and indirect OAM quantum numbers, ld and lind, respectively). The transfer of the indirect OAM is attributed to the following reason. As the circular component of the OVTs passes through the central section of the MDs perpendicular to the incident direction of the OVTs, the MDs can experience a q-plate-like ability with q = 1 such that the OVTs can obtain a corresponding OAM and the MDs can therefore obtain an OAM with same magnitude and opposite sign. This indirect OAM can lead to the self-induced orbital rotation of the MDs.
As mentioned above, the MDs can acquire different direct and indirect OAMs by changing the experimental condition. To methodically, qualitatively explore the influence of the above-mentioned conditions on the orbital rotation of the MDs, the investigation of this thesis is divided into three parts. The first part is to observe and record the self-induced orbital rotation of the CLC MDs under the manipulation of the circularly-polarized green laser beam (λ= 532 nm). This result can be explained by considering the differences of the indirectly transferred lind obtained at different experimental conditions. The second and third parts are to observe and record the orbital rotations of the CLC MDs under the manipulation of the OVTs (l = -8) as the reflection band of the CLC MDs includes or not the wavelength of the OVTs (for normal incidence), respectively. This result can be explained by considering the differences of the directly transferred ld and indirectly transferred lind obtained at different experimental conditions. Experimental results of the three parts display that, by varying the experimental conditions, e.g., handednesses of the CLC MDs and circularly-polarized component of the OVTs and the reflection band of the CLC MDs which is overlapping or not the wavelength of the OVTs, the transferred OAM with different magnitudes and signs can be obtained, resulting in different rotational behaviors of the MDs.

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