Cs 6S 1/2 4 F = 4= 7/2+1/2 F = 3 =7/2-1/2

Transcription

1 . 3. 1,2,. 1. 1,2,. 1,. 1,2,.,. 3 1, 2, 3

2 ( ) ( )

3 Cs 6S 1/2 4 F = 4= 7/2+1/ = ,2 =52 (0,52 ), F = 3 =7/2-1/2 3 = = 580

4 F g =3,4 : h -1 E 4 = 4 B (2m 4 1)GB 2 h -1 E 3 = 3 B + (2m 3 1)GB 2 3 = = G = 13,3 2 The main goal is to study the possibility of laser use for optical pumping of OPM in the terrestrial magnetic fields and to figure out the most efficient excitation transition.

5 Polarization by optical pumping D1 4-3 m F Trap states + L m F Laser emission interacts with one hyperfine ground level Resonance curve asymmetry due to quadratic Zeeman shift

6 L B. M x, , Cs

7 :.. + Cs

8 ) (). VCSEL)

9 -P,T inv),...: /2, /2, *,,, *, * *,,, ( (1 0,01)

10 :, : - ) - ) - ), ) Fe=4 Fe=3 6 2 P 1/2 Fe=4 Fe=3 6 2 P 1/2 Fg=4 Fg=4 6 2 S 1/2 6 2 S 1/2 Fg=3 Fg=3

11 Cs 6S 1/2 4 F = 4= 7/2+1/ = , F = 3 =7/2-1/2 3 = = 580

12 133 Cs 6 2 P 3/ MHz 203 MHz 125 MHz Fe=5 Fe=4 Fe=3 Fe=2? D 2 line (852.1 nm) Fg=4 6 2 P 1/2 1.2 GHz Fe=4 Fe=3 D 1 line (894.3 nm) 6 2 S 1/ GHz Fg=3

13 ,» ), )

14 ), L ( ) ) , (VCSEL) 6. ULM

15 633, 638, 769, 780, 795, 808, 842, 852, 895, MHz 10 mw PZT >6 GHz PZT >30 GHz 2nm - 30.; > 40 V.V.Vassiliev: vvv@okb.lpi.troitsk.ru S.A. Zibrov

16 Linewidth Output power 1 MHz 10 mw Continouos tuning range with PZT only with PZT and current >6 GHz >30 GHz Coarse tuning range nm 2 V.V.Vassiliev: vvv@okb.lpi.troitsk.ru

17 Principal scheme of the Mx magnetometer Mx or 45 o configuration: MF to be measured (B 0 ) is oriented at 45 o with respect to the laser beam Cs cell with paraffin wall coating or buffer gas Sensor head L P B 0 L Multimode fiber /4 RF coils PD Amplifier Light source Phase To frequency counter and oscilloscope L lens, P polarizer, /4 quarter-wave plate, PD photodiode Light source ECDL, gas discharge lamp, or solitary short cavity DL

18

19 Principal scheme of the experimental setup Optical scheme Electronic scheme

20 ,,

21 Cs cell with paraffin wall coating or buffer gas Sensor head L P B 0 L Multimode fiber /4 RF coils PD Amplifier Light source Noise generator (1 800 khz) To frequency counter, oscilloscope or spectrum analyzer Time domain 40 FFT khz 20 Amplitude Power, db 0-20 Time Frequency, khz

22 Gradiometer L P B 0 L /4 RF coils PD Amplifier Feedback electronics Light source L P B 0 L Amplifier /4 RF coils PD

23 Excitation by extended cavity diode laser (coated cells) Transition F g F e Fe=4 Fe=3 Self-oscillation yes no? no no D 1 -line excitation 6 2 P 1/2 Amplitude of 40mV was reached when the photocurrent of PD was: 14 A in case of laser excitation 155 A in case of lamp excitation For the F g =3 F e =2 transition amplitude of 40mV was reached when the photocurrent of PD was: 10 A in case of laser excitation 155 A in case of lamp excitation D 2 -line excitation Fe=5 Fe=4 Fe=3 Fe=2 Transition F g F e Self-oscillation yes no no yes no no 6 2 P3 /2 Fg=4 Fg=4 Fg=3 6 2 S 1/2 Fg=3 6 2 S 1/2

24 133 Cs 6 2 P 3/ MHz 203 MHz 125 MHz Fe=5 Fe=4 Fe=3 Fe=2 D 2 line (852.1 nm) 6 2 P 1/2 1.2 GHz Fe=4 Fe=3 Fg=4 D 1 line (894.3 nm) 6 2 S 1/ GHz Fg=3

25 Short cavity edge-emitting diode laser Cs D 1 -line (894 nm) Two different cells were tested with this laser: Transmission F g =3-F e =4 F g =3-F e =3 F g =4-F e =4 A cell containing Cs and 200 Torr of 4 He as buffer gas (from MIP commercial magnetometer),4-4 and 4-3 overlap A Cs cell with paraffin wall coating Both cells are cylinders with dimension D=19mm, L=19mm F g =4-F e =3 Output power, mw I th ~5mA Frequency These transitions overlap Buffer gas cell Transition F g F e yes yes no no Paraffin coated cell Transition F g F e Selfoscillation Selfoscillation yes Same amplitude of the signal was obtained at the values of photocurrent of: no no no Current, ma 8 A (laser) and 27 A (lamp) for buffer gas cell (This setup had a filter, to cut out the D 2 line component). LD characteristics: Ith = 4-5 ma, Output power = 3 mw, Resonator length = 100 m 8 A (laser) and 82 A (lamp) for paraffin coated cell (Lamp light contained both D 1 and D 2 components I D1 =1.3I D2 )

26 Excitation by two extended cavity diode lasers Setup 6 2 P 3/2 PD Sensor head Fe=5 Fe=4 D 1 ECDL ~8% Fe=3 Fe=2 D 2 ECDL Control cell Feedback electronics Frequency counter D 2 line (852.1 nm) Fg= P 1/2 Fe=4 Fe=3 D1 line (894.3 nm) Oscilloscope Fg=3 6 2 S 1/2 D 1 -laser 1 2 Transition F g F e 4 3 without D 2 -laser 4 3 with D 2 -laser 4 4 without D 2 -laser 4 4 with D 2 -laser Self-oscillation yes yes no yes Signal level / Photocurrent 78 mv / 113 A 230 mv / 98 A 70 mv / 103 A D 2 -laser frequency was resonant with F g =3 F e =2 transition. Oscillation signal level was 53mV and the photocurrent was 12 A Self-oscillation frequency corresponded to the F=4 ground state gyromagnetic ratio. Other possible configurations are to be checked

27 , 3-2.

28 3-2.

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30 Cs cell with paraffin wall coating or buffer gas Sensor head L P B 0 L Multimode fiber /4 RF coils PD Amplifier Light source Noise generator (1 800 khz) To frequency counter, oscilloscope or spectrum analyzer Time domain 40 FFT khz 20 Amplitude Power, db 0-20 Time Frequency, khz

31 Cs : ,. ( 1, 592 ) (1-3 ).,,.

32 D N2 U = F = F = D N2 U = F = F = 3.

33 133 Cs 6 2 P 3/ MHz 203 MHz 125 MHz Fe=5 Fe=4 Fe=3 Fe=2 D 2 line (852.1 nm) 6 2 P 1/2 1.2 GHz Fe=4 Fe=3 Fg=4 D 1 line (894.3 nm) 6 2 S 1/ GHz Fg=3

34 (-100 )

35 . > 1??. D1 D2?. VCSEL.. VCSEL

36 ),. 10 D 2 F g =3 F e =2, ) ; D 1 -F g =3 F e =2. -1 ( 200, 20 20),, ) F g =3 F e =2 ( D 2 ) )..