Abstract

The enhanced Faraday effect in gases for optical frequencies near absorption lines provides a basis for modulating a light beam. In the present study, incident radiation consisting of the Zeeman s components of the D lines of sodium passed through a polarizer to the Faraday cell, which employed saturated sodium vapor at approximately 240°C as an optical medium. Rotation of the plane of polarization of radiation traversing the cell was modulated at frequencies as high as 698 Mc/sec. On the basis of cw modulation studies, there appears to be no reduction in the integrated time-varying Faraday effect for frequencies as high as 265 Mc/sec; this frequency is 1100 times the Larmor frequency in the magnetic fields involved and 26 times the natural linewidth. There was no evidence of any reduction in frequency response for pulsed modulation at 698 Mc/sec.

© 1964 Optical Society of America

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References

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  1. D. Macaluso and O. M. Corbino, Compt. Rend. 127, 518 (1898).
  2. R. W. Wood, Physical Optics (The Macmillan Company, New York, 1934), p. 283.
  3. N. Bohr, Naturwiss. 12, 1115 (1925).
    [CrossRef]
  4. W. Hanle, Z. Phys. 85, 304 (1933).
    [CrossRef]
  5. E. Bretscher and W. Deck, Helv. Phys. Acta 6, 229 (1933).
  6. H. A. Lorentz, The Theory of Electrons (B. G. Teubner, Leipzig, 1916).
  7. W. Kuhn, Danske Videnskabernes Selskab (Zürich Habilitationsschrift, 1926); excellent summary given by A. C. G. Mitchell and M. W. Zemansky, Resonance Radiation and Excited Atoms (Cambridge University Press, London, 1934), Appendix VII.
  8. A. C. G. Mitchell and M. W. Zemansky, Resonance Radiation and Excited Atoms (Cambridge University Press, London, 1934), P. 99.
  9. S. Dushman and J. M. Lafferty, Scientific Foundations of Vacuum Technology (John Wiley & Sons, Inc., New York, 1962), p. 696.

1933 (2)

W. Hanle, Z. Phys. 85, 304 (1933).
[CrossRef]

E. Bretscher and W. Deck, Helv. Phys. Acta 6, 229 (1933).

1925 (1)

N. Bohr, Naturwiss. 12, 1115 (1925).
[CrossRef]

1898 (1)

D. Macaluso and O. M. Corbino, Compt. Rend. 127, 518 (1898).

Bohr, N.

N. Bohr, Naturwiss. 12, 1115 (1925).
[CrossRef]

Bretscher, E.

E. Bretscher and W. Deck, Helv. Phys. Acta 6, 229 (1933).

Corbino, O. M.

D. Macaluso and O. M. Corbino, Compt. Rend. 127, 518 (1898).

Deck, W.

E. Bretscher and W. Deck, Helv. Phys. Acta 6, 229 (1933).

Dushman, S.

S. Dushman and J. M. Lafferty, Scientific Foundations of Vacuum Technology (John Wiley & Sons, Inc., New York, 1962), p. 696.

Hanle, W.

W. Hanle, Z. Phys. 85, 304 (1933).
[CrossRef]

Kuhn, W.

W. Kuhn, Danske Videnskabernes Selskab (Zürich Habilitationsschrift, 1926); excellent summary given by A. C. G. Mitchell and M. W. Zemansky, Resonance Radiation and Excited Atoms (Cambridge University Press, London, 1934), Appendix VII.

Lafferty, J. M.

S. Dushman and J. M. Lafferty, Scientific Foundations of Vacuum Technology (John Wiley & Sons, Inc., New York, 1962), p. 696.

Lorentz, H. A.

H. A. Lorentz, The Theory of Electrons (B. G. Teubner, Leipzig, 1916).

Macaluso, D.

D. Macaluso and O. M. Corbino, Compt. Rend. 127, 518 (1898).

Mitchell, A. C. G.

A. C. G. Mitchell and M. W. Zemansky, Resonance Radiation and Excited Atoms (Cambridge University Press, London, 1934), P. 99.

Wood, R. W.

R. W. Wood, Physical Optics (The Macmillan Company, New York, 1934), p. 283.

Zemansky, M. W.

A. C. G. Mitchell and M. W. Zemansky, Resonance Radiation and Excited Atoms (Cambridge University Press, London, 1934), P. 99.

Compt. Rend. (1)

D. Macaluso and O. M. Corbino, Compt. Rend. 127, 518 (1898).

Helv. Phys. Acta (1)

E. Bretscher and W. Deck, Helv. Phys. Acta 6, 229 (1933).

Naturwiss. (1)

N. Bohr, Naturwiss. 12, 1115 (1925).
[CrossRef]

Z. Phys. (1)

W. Hanle, Z. Phys. 85, 304 (1933).
[CrossRef]

Other (5)

R. W. Wood, Physical Optics (The Macmillan Company, New York, 1934), p. 283.

H. A. Lorentz, The Theory of Electrons (B. G. Teubner, Leipzig, 1916).

W. Kuhn, Danske Videnskabernes Selskab (Zürich Habilitationsschrift, 1926); excellent summary given by A. C. G. Mitchell and M. W. Zemansky, Resonance Radiation and Excited Atoms (Cambridge University Press, London, 1934), Appendix VII.

A. C. G. Mitchell and M. W. Zemansky, Resonance Radiation and Excited Atoms (Cambridge University Press, London, 1934), P. 99.

S. Dushman and J. M. Lafferty, Scientific Foundations of Vacuum Technology (John Wiley & Sons, Inc., New York, 1962), p. 696.

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Figures (6)

Fig. 1
Fig. 1

Diagram of functional parts of a light beam modulation experiment. Magnet M and sodium spectral lamp S form a 2150-G Zeeman effect source. Polarizer P selects the s components of the D lines.

Fig. 2
Fig. 2

Transmission of s components of a 2150-G Zeeman pattern through saturated sodium vapor at various temperatures. Frequency displacement n from center of respective D absorption line is in units of 1700 Mc/sec, the 500°K Doppler breadth. The degree numbers above one set of Zeeman components indicate the Faraday rotation developed at the line center frequency in 9.6 cm of vapor with a 3.1-G axial field for the vapor temperature shown. Pattern (a), incident intensity. (Also transmitted intensity for 20°C saturated vapor temperature.) Patterns (b), (c), and (d) are, respectively, the transmitted intensities for saturated vapor temperatures of 214°, 238°, and 261°C.

Fig. 3
Fig. 3

“Transfer characteristic” for the gaseous Faraday effect medium showing the theoretical response to a sine wave current. Experimental points were obtained from a normalized enlargement of the experimental response shown in Fig. 4.

Fig. 4
Fig. 4

Record of response.

Fig. 5
Fig. 5

Comparison of Faraday rotation effect in sodium vapor 236°C caused by: (1) 60 cps and 33 Mc/sec currents, and (2) 60 cps and 265 Mc/sec currents. The two experiments are independent; the vertical scale should not be used to compare sensitivities. The experimental data are presented by triangles △ for 60 cps, by open circles ○ for 33 Mc/sec, and by diamonds ♢ for 265 Mc/sec.

Fig. 6
Fig. 6

Photomultiplier response to a pulsed continuous wave modulation of the Faraday effect in saturated sodium vapor at 244°C. Photograph (a) is for a 370 Mc/sec modulation frequency. Photograph (b) is for a 698 Mc/sec modulation frequency. Major vertical lines represent 2-msec time intervals. In each photograph the smooth lower trace shows a synchronously displayed pulse derived from the crystal detector output of a radio-frequency sampling probe.

Tables (2)

Tables Icon

Table I Differential angle Δθ required for a new minimum with a 2.0-A direct current in the modulation coil around a sodium vapor cell illuminated by the s components of a 2150-G Zeeman pattern of the D1 and D2 lines of sodium.

Tables Icon

Table II Equivalent 60 cps rms current required to produce the same integrated photomultiplier output as one unit of radio-frequency rms current.

Equations (9)

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θ = V B l ,
V = N e 2 f 8 π m 2 c 2 ( ν 0 - ν ) 2 m α m β m ,
T ( ν ) = I ( ν ) / I 0 ( ν ) = e - k ( ν ) l ,
k ( ν 0 ) = ( 2 / δ d ν ) ( ln 2 / π ) 1 2 ( π e 2 / m c ) N f ,
k ( ν ) ~ k ( ν 0 ) / n 2 .
V 1 = 0.52 × 10 - 13 N / n 2 , V 2 = 0.91 × 10 - 13 N / n 2 ,
k 1 ( ν 0 ) = 48 N × 10 - 13 , k 2 ( ν 0 ) = 96 N × 10 - 13 ,
I = C [ 2 sin 2 ( 8.6 i + 45° ) + 1.6 sin 2 ( 22 i + 45° ) + sin 2 ( 10 i + 45° ) ] ,
I = K sin 2 θ K θ 2 = K H 2 = K i 2 ,