Abstract

By use of dynamic subtraction it is feasible to adopt phase-sensitive detection with a CCD camera to reduce long-term optical background drift. We report on a two-order improvement of the signal-to-noise ratio. The improved system is used to image terahertz field distribution generated by an optically rectified electro-optic crystal with a modulation depth as small as 10-4. We also introduce a modified detection geometry that realizes near-field imaging capability with greatly improved spatial resolution.

© 2000 Optical Society of America

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References

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    [CrossRef] [PubMed]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
  10. Z. G. Lu, P. Campbell, X.-C. Zhang, “Free-space electro-optic sampling with a high-repetition-rate regenerative amplified laser,” Appl. Phys. Lett. 71, 593–595 (1997).
    [CrossRef]
  11. Z. Jiang, F. G. Sun, Q. Chen, X.-C. Zhang, “Electro-optic sampling near zero optical bias point,” Appl. Phys. Lett. 74, 1191–1193 (1999).
    [CrossRef]
  12. Q. Chen, X.-C. Zhang, “Polarization modulation in optoelectronic generation and detection of terahertz beams,” Appl. Phys. Lett. 74, 3435–3437 (1999).
    [CrossRef]

1999 (5)

1998 (1)

1997 (2)

D. You, P. H. Bucksbaum, “Propagation of half-cycle far infrared pulses,” J. Opt. Soc. Am. B 14, 1651–1655 (1997).
[CrossRef]

Z. G. Lu, P. Campbell, X.-C. Zhang, “Free-space electro-optic sampling with a high-repetition-rate regenerative amplified laser,” Appl. Phys. Lett. 71, 593–595 (1997).
[CrossRef]

1996 (3)

D. M. Mittleman, R. H. Jacobsen, M. C. Nuss, “T-ray imaging,” IEEE J. Sel. Top. Quantum Electron. 2, 679–692 (1996).
[CrossRef]

Z. L. Horvath, J. Vinko, Z. Bor, D. von der Linde, “Acceleration of femtosecond pulses to superluminal velocities by Gouy phase shift,” Appl. Phys. B 63, 481–484 (1996).
[CrossRef]

Q. Wu, T. D. Hewitt, X.-C. Zhang, “Two-dimensional electro-optic imaging of THz beams,” Appl. Phys. Lett. 69, 1026–1028 (1996).
[CrossRef]

1995 (1)

Bor, Z.

Z. L. Horvath, J. Vinko, Z. Bor, D. von der Linde, “Acceleration of femtosecond pulses to superluminal velocities by Gouy phase shift,” Appl. Phys. B 63, 481–484 (1996).
[CrossRef]

Bucksbaum, P. H.

Campbell, P.

Z. G. Lu, P. Campbell, X.-C. Zhang, “Free-space electro-optic sampling with a high-repetition-rate regenerative amplified laser,” Appl. Phys. Lett. 71, 593–595 (1997).
[CrossRef]

Chen, Q.

Z. Jiang, F. G. Sun, Q. Chen, X.-C. Zhang, “Electro-optic sampling near zero optical bias point,” Appl. Phys. Lett. 74, 1191–1193 (1999).
[CrossRef]

Q. Chen, X.-C. Zhang, “Polarization modulation in optoelectronic generation and detection of terahertz beams,” Appl. Phys. Lett. 74, 3435–3437 (1999).
[CrossRef]

Feng, S.

Hellwarth, R. W.

Hewitt, T. D.

Q. Wu, T. D. Hewitt, X.-C. Zhang, “Two-dimensional electro-optic imaging of THz beams,” Appl. Phys. Lett. 69, 1026–1028 (1996).
[CrossRef]

Horvath, Z. L.

Z. L. Horvath, J. Vinko, Z. Bor, D. von der Linde, “Acceleration of femtosecond pulses to superluminal velocities by Gouy phase shift,” Appl. Phys. B 63, 481–484 (1996).
[CrossRef]

Hu, B. B.

Hunsche, S.

Ippen, E. P.

Jacobsen, R. H.

D. M. Mittleman, R. H. Jacobsen, M. C. Nuss, “T-ray imaging,” IEEE J. Sel. Top. Quantum Electron. 2, 679–692 (1996).
[CrossRef]

Jaroszynski, D. A.

Jiang, Z.

Z. Jiang, F. G. Sun, Q. Chen, X.-C. Zhang, “Electro-optic sampling near zero optical bias point,” Appl. Phys. Lett. 74, 1191–1193 (1999).
[CrossRef]

Kaplan, A. E.

Leitenstorfer, A.

Lu, Z. G.

Z. G. Lu, P. Campbell, X.-C. Zhang, “Free-space electro-optic sampling with a high-repetition-rate regenerative amplified laser,” Appl. Phys. Lett. 71, 593–595 (1997).
[CrossRef]

Mittleman, D. M.

D. M. Mittleman, R. H. Jacobsen, M. C. Nuss, “T-ray imaging,” IEEE J. Sel. Top. Quantum Electron. 2, 679–692 (1996).
[CrossRef]

Nuss, M. C.

Sun, F. G.

Z. Jiang, F. G. Sun, Q. Chen, X.-C. Zhang, “Electro-optic sampling near zero optical bias point,” Appl. Phys. Lett. 74, 1191–1193 (1999).
[CrossRef]

Vinko, J.

Z. L. Horvath, J. Vinko, Z. Bor, D. von der Linde, “Acceleration of femtosecond pulses to superluminal velocities by Gouy phase shift,” Appl. Phys. B 63, 481–484 (1996).
[CrossRef]

von der Linde, D.

Z. L. Horvath, J. Vinko, Z. Bor, D. von der Linde, “Acceleration of femtosecond pulses to superluminal velocities by Gouy phase shift,” Appl. Phys. B 63, 481–484 (1996).
[CrossRef]

Winful, H. G.

Wu, Q.

Q. Wu, T. D. Hewitt, X.-C. Zhang, “Two-dimensional electro-optic imaging of THz beams,” Appl. Phys. Lett. 69, 1026–1028 (1996).
[CrossRef]

Wynne, K.

You, D.

Zhang, X.-C.

Q. Chen, X.-C. Zhang, “Polarization modulation in optoelectronic generation and detection of terahertz beams,” Appl. Phys. Lett. 74, 3435–3437 (1999).
[CrossRef]

Z. Jiang, F. G. Sun, Q. Chen, X.-C. Zhang, “Electro-optic sampling near zero optical bias point,” Appl. Phys. Lett. 74, 1191–1193 (1999).
[CrossRef]

Z. G. Lu, P. Campbell, X.-C. Zhang, “Free-space electro-optic sampling with a high-repetition-rate regenerative amplified laser,” Appl. Phys. Lett. 71, 593–595 (1997).
[CrossRef]

Q. Wu, T. D. Hewitt, X.-C. Zhang, “Two-dimensional electro-optic imaging of THz beams,” Appl. Phys. Lett. 69, 1026–1028 (1996).
[CrossRef]

Appl. Phys. B (1)

Z. L. Horvath, J. Vinko, Z. Bor, D. von der Linde, “Acceleration of femtosecond pulses to superluminal velocities by Gouy phase shift,” Appl. Phys. B 63, 481–484 (1996).
[CrossRef]

Appl. Phys. Lett. (4)

Q. Wu, T. D. Hewitt, X.-C. Zhang, “Two-dimensional electro-optic imaging of THz beams,” Appl. Phys. Lett. 69, 1026–1028 (1996).
[CrossRef]

Z. G. Lu, P. Campbell, X.-C. Zhang, “Free-space electro-optic sampling with a high-repetition-rate regenerative amplified laser,” Appl. Phys. Lett. 71, 593–595 (1997).
[CrossRef]

Z. Jiang, F. G. Sun, Q. Chen, X.-C. Zhang, “Electro-optic sampling near zero optical bias point,” Appl. Phys. Lett. 74, 1191–1193 (1999).
[CrossRef]

Q. Chen, X.-C. Zhang, “Polarization modulation in optoelectronic generation and detection of terahertz beams,” Appl. Phys. Lett. 74, 3435–3437 (1999).
[CrossRef]

IEEE J. Sel. Top. Quantum Electron. (1)

D. M. Mittleman, R. H. Jacobsen, M. C. Nuss, “T-ray imaging,” IEEE J. Sel. Top. Quantum Electron. 2, 679–692 (1996).
[CrossRef]

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

J. Opt. Soc. Am. B (2)

Opt. Lett. (3)

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Figures (6)

Fig. 1
Fig. 1

(a) Experimental setup of terahertz imaging with dynamic subtraction, (b) timing diagram between the CCD output and the EO modulator trigger signals.

Fig. 2
Fig. 2

Typical residual counts from a patterned target after 1000 averages with (a) dynamic subtraction and (b) conventional average. The rms counts are 0.15 and 24.0/frame for (a) and (b), respectively. 2D images of a terahertz field measured with (c) dynamic subtraction and (d) conventional subtraction.

Fig. 3
Fig. 3

Electric field distribution measured with dynamic subtraction from an optical rectification emitter. (a) 2D distribution at peak signal; (b) temporal waveform at the main peak; (c) and (d) 1D spatial and 1D temporal distribution at and 1.5 cm away from the focal plane, respectively.

Fig. 4
Fig. 4

Electric field distribution of terahertz pulse in xz plane at time zero.

Fig. 5
Fig. 5

Near-field 2D terahertz imaging. The probe beam is reflected by the EO crystal at the surface facing the object; therefore the object can be located close to the EO crystal without blocking the probe beam.

Fig. 6
Fig. 6

Terahertz imaging of a mask with three letters THz taken by the near-field geometry in Fig. 5 and the dynamic subtraction technique in Fig. 1.

Equations (2)

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S=n=1N In-n=M+1M+N Inn=1N In+n=M+1M+N In,  M>N,
S=n=1NI2n-I2n-1n=1NI2n+I2n-1.

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