Abstract

The use of a Sagnac interferometer as an acoustic sensor is discussed. Compared with a Mach–Zehnder interferometer it has the advantage of zero path-length difference. The sensitivity for low frequencies is shown to be proportional to frequency. With a passive homodyne-detection scheme using a 3 × 3 directional coupler, we report a noise-equivalent phase shift of 2.5×107rad/Hz at 10 kHz. The detectivity is believed to be limited by backscattered light.

© 1989 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. E. Udd, Proc. Soc. Photo-Opt. Instrum. Eng. 425, 90 (1983).
  2. R. G. Priest, IEEE Trans. Microwave Theory Tech. MTT-30, 1589 (1982).
    [CrossRef]
  3. T. H. Wood, R. A. Linke, B. L. Kasper, E. C. Carr, IEEE J. Lightwave Technol. 6, 346 (1988).
    [CrossRef]
  4. B. Moslehi, IEEE J. Lightwave Technol. LT-4, 1704 (1986).
    [CrossRef]
  5. K. Takada, J. Opt. Soc. Am. A 2, 872 (1985).
    [CrossRef]

1988 (1)

T. H. Wood, R. A. Linke, B. L. Kasper, E. C. Carr, IEEE J. Lightwave Technol. 6, 346 (1988).
[CrossRef]

1986 (1)

B. Moslehi, IEEE J. Lightwave Technol. LT-4, 1704 (1986).
[CrossRef]

1985 (1)

1983 (1)

E. Udd, Proc. Soc. Photo-Opt. Instrum. Eng. 425, 90 (1983).

1982 (1)

R. G. Priest, IEEE Trans. Microwave Theory Tech. MTT-30, 1589 (1982).
[CrossRef]

Carr, E. C.

T. H. Wood, R. A. Linke, B. L. Kasper, E. C. Carr, IEEE J. Lightwave Technol. 6, 346 (1988).
[CrossRef]

Kasper, B. L.

T. H. Wood, R. A. Linke, B. L. Kasper, E. C. Carr, IEEE J. Lightwave Technol. 6, 346 (1988).
[CrossRef]

Linke, R. A.

T. H. Wood, R. A. Linke, B. L. Kasper, E. C. Carr, IEEE J. Lightwave Technol. 6, 346 (1988).
[CrossRef]

Moslehi, B.

B. Moslehi, IEEE J. Lightwave Technol. LT-4, 1704 (1986).
[CrossRef]

Priest, R. G.

R. G. Priest, IEEE Trans. Microwave Theory Tech. MTT-30, 1589 (1982).
[CrossRef]

Takada, K.

Udd, E.

E. Udd, Proc. Soc. Photo-Opt. Instrum. Eng. 425, 90 (1983).

Wood, T. H.

T. H. Wood, R. A. Linke, B. L. Kasper, E. C. Carr, IEEE J. Lightwave Technol. 6, 346 (1988).
[CrossRef]

IEEE J. Lightwave Technol. (2)

T. H. Wood, R. A. Linke, B. L. Kasper, E. C. Carr, IEEE J. Lightwave Technol. 6, 346 (1988).
[CrossRef]

B. Moslehi, IEEE J. Lightwave Technol. LT-4, 1704 (1986).
[CrossRef]

IEEE Trans. Microwave Theory Tech. (1)

R. G. Priest, IEEE Trans. Microwave Theory Tech. MTT-30, 1589 (1982).
[CrossRef]

J. Opt. Soc. Am. A (1)

Proc. Soc. Photo-Opt. Instrum. Eng. (1)

E. Udd, Proc. Soc. Photo-Opt. Instrum. Eng. 425, 90 (1983).

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (3)

Fig. 1
Fig. 1

Schematic of the Sagnac acoustic sensor.

Fig. 2
Fig. 2

Sensitivity versus the normalized frequency for the Sagnac and Mach–Zehnder acoustic sensors. Solid curve, Sagnac (Lt = 2Ls); dashed curve, Sagnac (Lt = 4Ls); dotted curve, Sagnac (Lt = 6Ls); dashed-dotted curve, Mach–Zehnder.

Fig. 3
Fig. 3

Outputs of the interferometer with a harmonic signal applied to the signal coil.

Tables (1)

Tables Icon

Table 1 Noise-Equivalent Phase Shift (NEϕ) at Different Outputs at 10 kHz with a 1-Hz Bandwidth

Equations (12)

Equations on this page are rendered with MathJax. Learn more.

ϕ cw = 0 L t β [ x , t ( L t x ) n c ] d x , ϕ ccw = 0 L t β ( x , t x n c ) d x ,
β ( x , t ) = β 0 + δ β sin ( ω a t ) ,
Δ ϕ ( t ) = ϕ cw ϕ ccw = δ ϕ cos [ ω a ( t L t n 2 c ) ] ,
δ ϕ = δ β 2 c ω a n { cos [ ω a n 2 c ( L t 2 L s ) ] cos ( ω a n 2 c L t ) }
δ ϕ MZ = δ β 2 c ω a n sin ( ω a n L s 2 c ) .
δ ϕ = δ β ω a n c L s ( L t L s ) ,
δ ϕ MZ = δ β L s .
I 1 = 2 9 R P 0 { 1 + cos [ Δ ϕ ( t ) 120 ° ] } , I 3 = 2 9 R P 0 { 1 + cos [ Δ ϕ ( t ) 120 ° ] } ,
I diff = I 1 I 3 = A 2 3 9 R P 0 sin { δ ϕ cos [ ω a ( t L t n 2 c ) ] } ,
I diff = A 2 3 9 R P 0 δ ϕ cos [ ω a ( t L t n 2 c ) ] .
i n = 2 A ( e I d B ) 1 / 2 ,
NE ϕ = ( 2 e B 3 I d ) 1 / 2 .

Metrics