Assessment of a Rubidium ESFADOF Edge-Filter as ... - tuprints

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46 3 (Excited State) Faraday Anomalous Dispersion Optical Filters 1.0 0.5 0.9 Transmission 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.4 0.3 0.2 0.1 Norm. Brillouin-Backscatter Norm. Signal 0.1 0.0 -15 -10 -5 0 5 10 0.0 15 ∆ν / GHz 0.8 0.7 0.6 0 10 20 30 40 Water Temperature / °C Fig. 3.3: Simulated transmission characteristics of a simplified (I = 0) FADOF edge–filter, which operates on the S 1/2 → P 1/2 transition: The upper part shows the FADOF transmission, which results when inserting the simulated complex refractive indices, which are compiled in Fig. 3.2, into Eq. 3.8, together with the transmitted intensity of the Brillouin–backscatter. The latter has been computed according to the discussion of Sec. 2.3 for a water temperature of T = 20 ◦ C and a salinity of S = 35‰. It has been normalized to the total intensity of the Brillouin–backscatter, so that its area corresponds to the normalized transmission signal of the FADOF edge-filter. A variation of the water temperature leads to the characteristic curve of the Brillouin–lidar, which is the lower part of the figure. The circled data point corresponds to the spectral integral of the transmitted and normalized Brillouin–backscatter of the upper part. In conclusion, FADOFs potentially deliver the desired steep transmission edges within the region of interest (grayed areas in the upper graph). They can be employed as edge-filter receiver. filled curve in the upper graph corresponds to the normalized transmission signal of the FADOF edge-filter. The normalization has been performed with respect to the total integrated intensity of the Brillouin–doublet. By performing this procedure for different water temperatures, it follows that the presented FADOF filter characteristics are suited as edge–filter receiver for the Brillouin–lidar. The lower part of Fig. 3.3 reveals a clear dependency of the normalized signal on the water temperature. In conclusion, FADOFs potentially
3.6 Extension to Excited State FADOFs: ESFADOFs 47 deliver the desired steep and symmetric edge–filter characteristics within the region of interest and are therefore a very promissing development towards an operational Brillouin–lidar. The next section touches on the extension towards real systems. 3.5 Rubidium Ground State FADOF First investigations of the author within the Brillouin–lidar project concentrated on ground state FADOFs. These works theoretically and experimentally investigated a Rubidium based FADOF system, which operates on the 5S 1/2 → 5P 3/2 ground state transition. The obtained results have been published [16, 20, 21] prior to this work and are not the purpose of this thesis. However, they experimentally and theoretically prove that FADOFs are able to deliver steep and symmetrical transmission edges. An excellent agreement between the experimental data and the theoretical description has been demonstrated. Fig. 3.4 shows a comparison of the experimental data with the presented theory. The figure is intended to prove the mentioned excellent agreement between the experiment and the theoretical approach without any further discussion of the experimental details. They can be found in the cited works. Furthermore, Fig. 3.4 shows that real FADOF systems are capable of delivering steep and symmetric transmission edges. According to the discussion of the last section, the steep and symmetric transmission edges of FADOF or ESFADOF devices can be employed as high resolution edge-filters. In addition, these edges are tunable within a few GHz around the central frequency of the employed transition by adjusting the magnetic field strength and/or the number density of the atomic vapor. The former influences S γ,γ′ r and the latter N(γ). 3.6 Extension to Excited State FADOFs: ESFADOFs The presented theoretical framework can be applied to excited state Faraday anomalous dispersion optical filters as well. This work investigates Rubidium based ESFADOFs on the 5P 3/2 → 8D 5/2 transition (cf. Fig. 3.1). Consequently, γ → γ ′ refer to all possible transitions within the corresponding Zeeman– multiplets. In addition, as the ESFADOF operating transition becomes accessible through the external optical pumping process, which populates the lower ESFADOF state, the number density of the lower ESFADOF state N(γ) can not be described any more by a Boltzmann–distribution (cf. Eq. 3.29). In fact, N(γ) is strongly correlated to the exact spatial and spectral pump geometry. As Eqs. 3.25 and 3.28 indicate, a strongly populated lower ESFADOF state N(γ) increases the signal strength of the transmitted light. Thus, high pump intensities as well as high opacities of the vapor are advantageous. On the other hand, high power lasers increase the complexity of the system considerably. They
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INSTITUT FÜR ANGEWANDTE PHYSIK TEC
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Abstract Global and local climate c
Page 7: Pentru Alexandru şi Florina
Page 10 and 11: II Contents 4.3 Measurement Unit .
Page 12 and 13: 2 1 Introduction wide sea currents
Page 15 and 16: 2 Remote Sensing of the Water Colum
Page 17 and 18: 2.1 Measurement Principle 7 highly
Page 19 and 20: 2.1 Measurement Principle 9 Fry and
Page 21 and 22: 2.2 System Requirements 11 operatin
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Page 25 and 26: 2.2 System Requirements 15 Table 2.
Page 27 and 28: 2.2 System Requirements 17 1. Rayle
Page 29 and 30: 2.2 System Requirements 19 wave. Th
Page 31 and 32: 2.2 System Requirements 21 cent pro
Page 33 and 34: 2.2 System Requirements 23 Fig. 2.6
Page 35 and 36: 2.2 System Requirements 25 Both the
Page 37 and 38: 2.3 Ideal Edge-Filter 27 of the Bri
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Page 42 and 43: 32 3 (Excited State) Faraday Anomal
Page 70 and 71: 60 4 Experimental Investigations of
Page 99 and 100: 5 Discussion of the Experimental Re
Page 101 and 102: 5.1 Overview of the Experimental Pa
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Page 105 and 106: 5.2 Vapor Cell I: 270 mT 95 5.2 Vap
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5.2 Vapor Cell I: 270 mT 97 0.20 5.
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5.2 Vapor Cell I: 270 mT 99 Fig. 5.
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5.2 Vapor Cell I: 270 mT 101 introd
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5.2 Vapor Cell I: 270 mT 103 Fig. 5
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5.2 Vapor Cell I: 270 mT 105 which
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0.15 ∆ν P = 0.98(2) GHz 5.2 Vapo
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5.3 ESFADOF Operational Limits 109
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cesses of the atomic vapor. This al
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Fig. 5.18: Rubidium Grotian energy
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5.4 Vapor Cell II: 500 mT 133 maxim
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5.4 Vapor Cell II: 500 mT 135 the P
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5.4 Vapor Cell II: 500 mT 137 such
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6 Conclusion and Outlook The presen
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6 Conclusion and Outlook 141 pulses
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6 Conclusion and Outlook 143
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Appendix
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148 A Rubidium Atom 2. Relevant ato
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B Manufacturing process of Rb Vapor
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B Manufacturing process of Rb Vapor
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C Magnetic Field Strengths of the E
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D Tripod ECDL Fig. D.1: Schematic o
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160 References [10] G.L. Mellor and
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162 References [41] E.S. Fry, J. Ka
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164 References [69] Claude C. Leroy
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166 References [97] L. Goldberg, D.
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168 References [125] Cord Fricke-Be
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170 References [158] Triad Technolo
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172 References [186] M. Cheret, L.
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Curriculum Vitae Alexandru Lucian P
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178 1 Publications Conference Proce
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Supervised Theses Denise Stang, Wei
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184 1 Danksagung Bei Herrn Arno Wei
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