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Light Amplification in Diode-pumped Cesium Vapor Cell

다이오드 펌프 세슘 원자 증기에서의 증폭

  • Hwang, Jongmin (Department of Physics, Pusan National University) ;
  • Jeong, Taek (Department of Physics, Pusan National University) ;
  • Moon, Han Seb (Department of Physics, Pusan National University)
  • 황종민 (부산대학교 물리학과) ;
  • 정택 (부산대학교 물리학과) ;
  • 문한섭 (부산대학교 물리학과)
  • Received : 2018.11.01
  • Accepted : 2018.11.26
  • Published : 2018.12.25

Abstract

We report amplification of a small signal in a diode-pumped Cs vapor cell with 500 torr of ethane buffer gas, in the low-pump-power regime of 200 mW or less. For efficient amplifier operation, the pump and signal beams were coupled to a single-mode optical fiber, and completely overlapped in the Cs vapor cell. We investigated the amplification of the small signal according to cell temperature, signal power, and pump power. An amplification factor of 56 was achieved under the conditions of cell temperature of $115^{\circ}C$, signal power of 0.1 mW, and pump power of 200 mW.

본 논문에서는 200 mW 이하의 낮은 펌핑 조건의 다이오드 펌프 세슘 증기 셀에서 약한 신호광 증폭을 보고한다. 고효율 증폭효과를 얻기 위해서 펌프빔과 신호빔을 하나의 단일 모드 광섬유로 통과시켜 세슘 증기 셀 내부에서 완전히 겹치도록 하였다. 우리는 약한 신호광의 증폭 정도를 셀의 온도, 신호광의 세기, 펌프광의 세기에 따라 조사하였다. 증기 셀의 온도 $115^{\circ}C$, 신호광의 출력 0.1 mW, 그리고 펌프광의 출력 200 mW인 조건에서 56배의 증폭효과를 얻을 수 있었다.

Keywords

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Fig. 1. Energy-level diagram for optically pumped alkali amplifier (OPAA) and saturated absorption spectra (SAS) of D1 and D2 transition of Cs atom. (a) Three-level atomic system with 5S5/2, 5P5/2, and 5P7/2 states of Cs. (b) SAS of the D2 transition for pump laser. (c) SAS of the D2 transition for signal laser.

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Fig. 2. Experimental setup for OPAA in Cs vapor cell with ethane buffer gas. Pump laser (wavelength 852 nm); signal laser (wavelength 895 nm); OI, optical isolator; SMF, single mode fiber; PBS, polarization beam splitter; HWP, half-wave plate; BF, bandpass filter.

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Fig. 3. Cs amplifier small signal amplification factor vs pump power according to the cell temperature (105℃, 110℃, and 115℃) under the condition of input signal of 0.1 mW.

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Fig. 4. Temperature dependence of (a) amplification coefficient and (b) gain coefficient under the condition of input signal of 0.1 mW and pump of 200 mW.

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Fig. 5. Cs amplifier small signal amplification factor vs pump power according to the input signal power (0.1 mW, 1 mW, 3 mW, 5 mW, and 10 mW) at the cell temperature of 115℃.

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Fig. 6. Input signal power dependence of (a) amplification coefficient and (b) gain extraction efficiency relative to the pump power under the condition of pump of 200 mW at the cell temperature of 115℃.

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