Abstract

In a demonstration of frequency modulation spectroscopy with a CO2 laser, sidebands at 1 GHz were generated using a CdTe electrooptic phase modulator driven either by 5-kW pulses from a microwave cavity oscilllator or by 10 W of cw power from a solid-state microwave amplifier. Frequency modulation signals resulting from sideband absorption by Fabry-Perot resonances were measured using a room-temperature 1-GHz bandwidth HgCdTe detector. Signal-to-noise ratios for the conditions of our experiments were ∼200:1 and limited by rf pickup noise in the detection electronics. Substantial improvements in SNR can be made by providing better rf shielding for the detection electronics and by using a liquid–nitrogen-cooled detector in conjunction with improved modulator designs.

© 1985 Optical Society of America

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References

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  1. R. S. Eng, J. F. Butler, K. J. Linden, “Tunable Diode Laser Spectroscopy: An Invited Review,” Opt. Eng. 19, 945 (1980).
    [CrossRef]
  2. J. Reid, M. El-Sherbiny, B. K. Garside, E. A. Ballik, “Sensitivity Limits of a Tunable Diode Lasr Spectrometer, with Application to the Detection of NO2 at the 100-ppt Level,” Appl. Opt. 19, 3349 (1980).
    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
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    [CrossRef]
  6. G. M. Carter, “Tunable High Efficiency Microwave Frequency-Shifting of Infrared Lasers,” Appl. Phys. Lett. 32, 810 (1978).
    [CrossRef]
  7. P. K. Cheo, “Frequency Synthesized and Continuously Tunable IR Laser Sources in 9- to 11-μm,” IEEE J. Quantum Electron. QE-20, 700 (1984).
    [CrossRef]
  8. S. Y. Wang, D. M. Bloom, “100-GHz Bandwidth Planar GaAs Schottky Photodiode,” Electron. Lett. 19, 554 (1983).
    [CrossRef]
  9. D. L. Spears, “Theory and Status of High Performance Heterodyne Detectors,” Proc. Soc. Photo-Opt. Instrum. Eng. 300, 174 (1981).
  10. D. E. Cooper, T. F. Gallagher, “Double Frequency Modulation Spectroscopy: High Modulation Frequency with Low-Bandwidth Detectors,” to be published in 15 Mar. issue of Appl. Opt.
  11. N. H. Tran, R. Kachru, T. F. Gallagher, J. P. Watjen, G. C. Bjorklund, “Generation of Microwaves by Mixing Two Optical Frequencies in a Nonlinear Crystal: A Novel Approach to High-Bandwidth Optical Mixers,” Opt. Lett. 10, 128 (1984).
    [CrossRef]
  12. G. C. Bjorklund, M. D. Levenson, W. Lenth, C. Ortiz, “Frequency Modulation (FM) Spectroscopy, Theory of Lineshapes and Signal-to-Noise Analysis,” Appl. Phys. B 32, 145 (1983).
    [CrossRef]
  13. S. Namba, “Electro-Optical Effect of Zincblende,” J. Opt. Soc. Am. 51, 76 (1961).
    [CrossRef]
  14. R. H. Kingston, Detection of Optical and Infrared Radiation (Springer, New York, 1978).

1984 (3)

1983 (2)

G. C. Bjorklund, M. D. Levenson, W. Lenth, C. Ortiz, “Frequency Modulation (FM) Spectroscopy, Theory of Lineshapes and Signal-to-Noise Analysis,” Appl. Phys. B 32, 145 (1983).
[CrossRef]

S. Y. Wang, D. M. Bloom, “100-GHz Bandwidth Planar GaAs Schottky Photodiode,” Electron. Lett. 19, 554 (1983).
[CrossRef]

1981 (1)

D. L. Spears, “Theory and Status of High Performance Heterodyne Detectors,” Proc. Soc. Photo-Opt. Instrum. Eng. 300, 174 (1981).

1980 (3)

1978 (1)

G. M. Carter, “Tunable High Efficiency Microwave Frequency-Shifting of Infrared Lasers,” Appl. Phys. Lett. 32, 810 (1978).
[CrossRef]

1970 (1)

F. S. Chen, “Modulators for Optical Communications,” Proc. IEEE 58, 1440 (1970).
[CrossRef]

1961 (1)

Ballik, E. A.

Bjorklund, G. C.

Bloom, D. M.

S. Y. Wang, D. M. Bloom, “100-GHz Bandwidth Planar GaAs Schottky Photodiode,” Electron. Lett. 19, 554 (1983).
[CrossRef]

Butler, J. F.

R. S. Eng, J. F. Butler, K. J. Linden, “Tunable Diode Laser Spectroscopy: An Invited Review,” Opt. Eng. 19, 945 (1980).
[CrossRef]

Carter, G. M.

G. M. Carter, “Tunable High Efficiency Microwave Frequency-Shifting of Infrared Lasers,” Appl. Phys. Lett. 32, 810 (1978).
[CrossRef]

Chen, F. S.

F. S. Chen, “Modulators for Optical Communications,” Proc. IEEE 58, 1440 (1970).
[CrossRef]

Cheo, P. K.

P. K. Cheo, “Frequency Synthesized and Continuously Tunable IR Laser Sources in 9- to 11-μm,” IEEE J. Quantum Electron. QE-20, 700 (1984).
[CrossRef]

Cooper, D. E.

D. E. Cooper, T. F. Gallagher, “Double Frequency Modulation Spectroscopy: High Modulation Frequency with Low-Bandwidth Detectors,” to be published in 15 Mar. issue of Appl. Opt.

El-Sherbiny, M.

Eng, R. S.

R. S. Eng, J. F. Butler, K. J. Linden, “Tunable Diode Laser Spectroscopy: An Invited Review,” Opt. Eng. 19, 945 (1980).
[CrossRef]

Gallagher, T. F.

N. H. Tran, R. Kachru, T. F. Gallagher, J. P. Watjen, G. C. Bjorklund, “Generation of Microwaves by Mixing Two Optical Frequencies in a Nonlinear Crystal: A Novel Approach to High-Bandwidth Optical Mixers,” Opt. Lett. 10, 128 (1984).
[CrossRef]

D. E. Cooper, T. F. Gallagher, “Double Frequency Modulation Spectroscopy: High Modulation Frequency with Low-Bandwidth Detectors,” to be published in 15 Mar. issue of Appl. Opt.

Garside, B. K.

Grant, W. B.

Kachru, R.

Kingston, R. H.

R. H. Kingston, Detection of Optical and Infrared Radiation (Springer, New York, 1978).

Lenth, W.

G. C. Bjorklund, M. D. Levenson, W. Lenth, C. Ortiz, “Frequency Modulation (FM) Spectroscopy, Theory of Lineshapes and Signal-to-Noise Analysis,” Appl. Phys. B 32, 145 (1983).
[CrossRef]

Levenson, M. D.

G. C. Bjorklund, M. D. Levenson, W. Lenth, C. Ortiz, “Frequency Modulation (FM) Spectroscopy, Theory of Lineshapes and Signal-to-Noise Analysis,” Appl. Phys. B 32, 145 (1983).
[CrossRef]

Linden, K. J.

R. S. Eng, J. F. Butler, K. J. Linden, “Tunable Diode Laser Spectroscopy: An Invited Review,” Opt. Eng. 19, 945 (1980).
[CrossRef]

Molina, L. T.

Namba, S.

Ortiz, C.

G. C. Bjorklund, M. D. Levenson, W. Lenth, C. Ortiz, “Frequency Modulation (FM) Spectroscopy, Theory of Lineshapes and Signal-to-Noise Analysis,” Appl. Phys. B 32, 145 (1983).
[CrossRef]

Reid, J.

Spears, D. L.

D. L. Spears, “Theory and Status of High Performance Heterodyne Detectors,” Proc. Soc. Photo-Opt. Instrum. Eng. 300, 174 (1981).

Tran, N. H.

Wang, S. Y.

S. Y. Wang, D. M. Bloom, “100-GHz Bandwidth Planar GaAs Schottky Photodiode,” Electron. Lett. 19, 554 (1983).
[CrossRef]

Watjen, J. P.

Appl. Opt. (2)

Appl. Phys. B (1)

G. C. Bjorklund, M. D. Levenson, W. Lenth, C. Ortiz, “Frequency Modulation (FM) Spectroscopy, Theory of Lineshapes and Signal-to-Noise Analysis,” Appl. Phys. B 32, 145 (1983).
[CrossRef]

Appl. Phys. Lett. (1)

G. M. Carter, “Tunable High Efficiency Microwave Frequency-Shifting of Infrared Lasers,” Appl. Phys. Lett. 32, 810 (1978).
[CrossRef]

Electron. Lett. (1)

S. Y. Wang, D. M. Bloom, “100-GHz Bandwidth Planar GaAs Schottky Photodiode,” Electron. Lett. 19, 554 (1983).
[CrossRef]

IEEE J. Quantum Electron. (1)

P. K. Cheo, “Frequency Synthesized and Continuously Tunable IR Laser Sources in 9- to 11-μm,” IEEE J. Quantum Electron. QE-20, 700 (1984).
[CrossRef]

J. Opt. Soc. Am. (1)

Opt. Eng. (1)

R. S. Eng, J. F. Butler, K. J. Linden, “Tunable Diode Laser Spectroscopy: An Invited Review,” Opt. Eng. 19, 945 (1980).
[CrossRef]

Opt. Lett. (2)

Proc. IEEE (1)

F. S. Chen, “Modulators for Optical Communications,” Proc. IEEE 58, 1440 (1970).
[CrossRef]

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

D. L. Spears, “Theory and Status of High Performance Heterodyne Detectors,” Proc. Soc. Photo-Opt. Instrum. Eng. 300, 174 (1981).

Other (2)

D. E. Cooper, T. F. Gallagher, “Double Frequency Modulation Spectroscopy: High Modulation Frequency with Low-Bandwidth Detectors,” to be published in 15 Mar. issue of Appl. Opt.

R. H. Kingston, Detection of Optical and Infrared Radiation (Springer, New York, 1978).

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Figures (5)

Fig. 1
Fig. 1

Optical power spectrum of amplitude-modulated (AM) CO2 laser light with a 2.5-GHz microwave drive frequency.

Fig. 2
Fig. 2

Optical power spectrum of frequency-modulated (FM) CO2 laser light with a 2.5-GHz microwave drive frequency.

Fig. 3
Fig. 3

Experimental configuration for pulsed modulator FM spectroscopy with a CO2 laser.

Fig. 4
Fig. 4

Inphase (a) and quadrature (b) FM signals resulting from the absorption of 1-GHz sidebands by resonances of a Fabry-Perot etalon. The signals were obtained by directing ∼30 mW of 10.6-μm optical power onto a 1-GHz bandwidth room-temperature HgCdTe detector. The sidebands, each containing ∼1% of the laser carrier optical power, were generated by driving the CdTe modulator with 5-kW microwave pulses.

Fig. 5
Fig. 5

Inphase (a) and quadrature (b) FM signals resulting from the absorption of 1-GHz sidebands by resonances of a Fabry-Perot etalon. The signals were obtained by directing ∼30 mW of 10.6-μm optical power onto a 1-GHz bandwidth room-temperature HgCdTe detector. The sidebands, each containing ∼0.005% of the laser carrier optical power, were generated by driving the CdTe modulator cw with 10 W of microwave power.

Equations (5)

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SNR = η P 0 ω c ( Δ δ ) 2 M 2 4 Δ f ,
SNR = ( D * P 0 ) 2 ( Δ δ ) 2 M 2 4 A Δ f ,
M = 2 π 3 λ l d n 0 3 r 41 V .
Δ δ min = 2 M ( ω c η P 0 Δ f ) 1 / 2 .
P 0 > 2 kThv η e 2 R .

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