透過原子系統建立雷射功率標準的提案與演示;A Proposal and Demonstration on Setting up Laser Power Standard via Atom System

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/96211

Title:	透過原子系統建立雷射功率標準的提案與演示;A Proposal and Demonstration on Setting up Laser Power Standard via Atom System
Authors:	陳可翰;Chen, Ko-Han
Contributors:	物理學系
Keywords:	銫原子;光功率標準;雙光子躍遷;Cesium atom;Power standard;Two-photon transition
Date:	2025-01-20
Issue Date:	2025-04-09 16:58:32 (UTC+8)
Publisher:	國立中央大學
Abstract:	本論文提出了一種基於銫原子 6S1/2 → 7S1/2 雙光子躍遷的創新光功率量測方法。通過研究原子躍遷中的 ACStark 頻移，本研究為建立功率量測標準奠定了基礎。在重力波觀測中，準確的絕對功率量測對於確定重力波事件源的距離至關重要。然而，現有的功率量測系統因感測器老化及量子效率不一致，導致測量結果存在偏差，需頻繁進行校正。原子躍遷提供了一種克服這些限制的方法，使光功率量測更具穩定性和可重現性。本研究開發了一套基於原子的光功率量測系統，整合了碘穩頻雷射、偏頻鎖定技術以及腔體增強的雙光子吸收光譜技術。碘穩頻雷射提供了不受 ACStark 頻移影響的頻率基準，偏頻鎖定則將其穩定性轉移至從屬雷射。透過利用光強度與 ACStark 頻移之間的線性關係，系統可實現準確且寬量測範圍的功率量測。腔體增強設計確保光束的波形與原子束交互區域良好定義，進一步降低不確定性。該系統展示了 0.56 kHz/mW 的功率頻率響應度，可量測功率的解析度為 5.4 mW，實驗可重置性為 3 kHz。目前光功率的不準度為 ∆P /P = 7 %，突顯此系統作為未來功率校正標準基礎的潛力。;This dissertation introduces an innovative approach to optical power measurement using the cesium 6S1/2 → 7S1/2 twophoton transition. The investigation of the ACStark shift in atomic transitions serves as a foundation for developing a power measurement standard. In gravitational wave observatories, accurate absolute power measurements are essential for determining source distances of gravitational wave events. However, the existing power measurement systems suf fer from inconsistencies due to sensor aging and varying quantum efficiencies, necessitating routine recalibrations. Atomic transitions provide a pathway to overcome these limitations by enabling robust, reproducible, and digital optical power measurements. The atombased power measurement system developed in this work integrates an iodine stabilized laser, offsetlocking technique, and cavityenhanced twophoton absorption spec troscopy. The iodinestabilized laser offers a frequency reference immune to the ACStark shift, while offsetlocking transfers its stability to the slave laser. By leveraging the linear relation ship between optical intensity and the ACStark shift, the system enables accurate and wide range power measurements. The cavityenhanced design ensures welldefined beam profiles and crosssectional areas for atombeam interactions, minimizing uncertainties. The system demonstrates a powerfrequency conversion factor of 0.56 kHz/mW, achieving the power measurement resolution of 5.4 mW and a resettability of spectral measurements of 3 kHz. The current power measurement uncertainty is ∆P /P = 7 % under typical operating conditions, highlighting the potential of this system as a foundation for future power calibration standards.
Appears in Collections:	[Graduate Institute of Physics] Electronic Thesis & Dissertation

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