Abstract

In previous publications [Opt. Express 20, 7388 (2012), Opt. Express 20, 28039 (2012)] we showed how a confocal configuration can form an surface plasmon microscope involving interference between a path involving the generation of surface plasmons and one involving a directly reflected beam. The relative phase of these contributions changes with axial scan position allowing the phase velocity of the surface plasmon to be measured. In this paper we extend the interferometer concept to produce an ‘embedded’ phase shifting interferometer, where we can control the phase between the reference and surface plasmon beams with a spatial light modulator. We demonstrate that this approach facilitates extraction of the amplitude and phase of the surface plasmon to measure of the phase velocity and the attenuation of the surface plasmons with greatly improved signal to noise compared to previous measurement approaches. We also show that reliable results are obtained over smaller axial scan ranges giving potentially superior lateral resolution.

© 2013 OSA

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References

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  1. B. Zhang, S. Pechprasarn, J. Zhang, and M. G. Somekh, “Confocal surface plasmon microscopy with pupil function engineering,” Opt. Express20(7), 7388–7397 (2012).
    [CrossRef] [PubMed]
  2. B. Zhang, S. Pechprasarn, and M. G. Somekh, “Surface plasmon microscopic sensing with beam profile modulation,” Opt. Express20(27), 28039–28048 (2012).
    [CrossRef] [PubMed]
  3. E. Kretschmann and H. Raether, “Radiative decay of non radiative surface plasmons excited by light,” Zeitschrift Fur Naturforschung Part a-Astrophysik Physik Und Physikalische Chemie A, 23(12), 2135 (1968).
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    [CrossRef]
  5. M. G. Somekh, S. G. Liu, T. S. Velinov, and C. W. See, “High-resolution scanning surface-plasmon microscopy,” Appl. Opt.39(34), 6279–6287 (2000).
    [CrossRef] [PubMed]
  6. M. G. Somekh, S. G. Liu, T. S. Velinov, and C. W. See, “Optical V(z) for high-resolution 2pi surface plasmon microscopy,” Opt. Lett.25(11), 823–825 (2000).
    [CrossRef] [PubMed]
  7. S. Pechprasarn and M. G. Somekh, “Surface plasmon microscopy: resolution, sensitivity and crosstalk,” J. Microsc.246(3), 287–297 (2012).
    [CrossRef] [PubMed]
  8. F. Argoul, T. Roland, A. Fahys, L. Berguiga, and J. Elezgaray, “Uncovering phase maps from surface plasmon resonance images: Towards a sub-wavelength resolution,” C. R. Phys.8(8), 800–814 (2012).
    [CrossRef]
  9. L. Berguiga, S. Zhang, F. Argoul, and J. Elezgaray, “High-resolution surface-plasmon imaging in air and in water: V(z) curve and operating conditions,” Opt. Lett.32(5), 509–511 (2007).
    [CrossRef] [PubMed]
  10. J. Kushibiki and N. Chubachi, “Material characterization by line-focus-beam acoustic microscope,” Trans. Sonics Ultrason.32(2), 189–212 (1985).
    [CrossRef]

2012

S. Pechprasarn and M. G. Somekh, “Surface plasmon microscopy: resolution, sensitivity and crosstalk,” J. Microsc.246(3), 287–297 (2012).
[CrossRef] [PubMed]

F. Argoul, T. Roland, A. Fahys, L. Berguiga, and J. Elezgaray, “Uncovering phase maps from surface plasmon resonance images: Towards a sub-wavelength resolution,” C. R. Phys.8(8), 800–814 (2012).
[CrossRef]

B. Zhang, S. Pechprasarn, J. Zhang, and M. G. Somekh, “Confocal surface plasmon microscopy with pupil function engineering,” Opt. Express20(7), 7388–7397 (2012).
[CrossRef] [PubMed]

B. Zhang, S. Pechprasarn, and M. G. Somekh, “Surface plasmon microscopic sensing with beam profile modulation,” Opt. Express20(27), 28039–28048 (2012).
[CrossRef] [PubMed]

2007

2000

1998

1985

J. Kushibiki and N. Chubachi, “Material characterization by line-focus-beam acoustic microscope,” Trans. Sonics Ultrason.32(2), 189–212 (1985).
[CrossRef]

1968

E. Kretschmann and H. Raether, “Radiative decay of non radiative surface plasmons excited by light,” Zeitschrift Fur Naturforschung Part a-Astrophysik Physik Und Physikalische Chemie A, 23(12), 2135 (1968).

Argoul, F.

F. Argoul, T. Roland, A. Fahys, L. Berguiga, and J. Elezgaray, “Uncovering phase maps from surface plasmon resonance images: Towards a sub-wavelength resolution,” C. R. Phys.8(8), 800–814 (2012).
[CrossRef]

L. Berguiga, S. Zhang, F. Argoul, and J. Elezgaray, “High-resolution surface-plasmon imaging in air and in water: V(z) curve and operating conditions,” Opt. Lett.32(5), 509–511 (2007).
[CrossRef] [PubMed]

Berguiga, L.

F. Argoul, T. Roland, A. Fahys, L. Berguiga, and J. Elezgaray, “Uncovering phase maps from surface plasmon resonance images: Towards a sub-wavelength resolution,” C. R. Phys.8(8), 800–814 (2012).
[CrossRef]

L. Berguiga, S. Zhang, F. Argoul, and J. Elezgaray, “High-resolution surface-plasmon imaging in air and in water: V(z) curve and operating conditions,” Opt. Lett.32(5), 509–511 (2007).
[CrossRef] [PubMed]

Chubachi, N.

J. Kushibiki and N. Chubachi, “Material characterization by line-focus-beam acoustic microscope,” Trans. Sonics Ultrason.32(2), 189–212 (1985).
[CrossRef]

Elezgaray, J.

F. Argoul, T. Roland, A. Fahys, L. Berguiga, and J. Elezgaray, “Uncovering phase maps from surface plasmon resonance images: Towards a sub-wavelength resolution,” C. R. Phys.8(8), 800–814 (2012).
[CrossRef]

L. Berguiga, S. Zhang, F. Argoul, and J. Elezgaray, “High-resolution surface-plasmon imaging in air and in water: V(z) curve and operating conditions,” Opt. Lett.32(5), 509–511 (2007).
[CrossRef] [PubMed]

Fahys, A.

F. Argoul, T. Roland, A. Fahys, L. Berguiga, and J. Elezgaray, “Uncovering phase maps from surface plasmon resonance images: Towards a sub-wavelength resolution,” C. R. Phys.8(8), 800–814 (2012).
[CrossRef]

Kano, H.

Kawata, S.

Kretschmann, E.

E. Kretschmann and H. Raether, “Radiative decay of non radiative surface plasmons excited by light,” Zeitschrift Fur Naturforschung Part a-Astrophysik Physik Und Physikalische Chemie A, 23(12), 2135 (1968).

Kushibiki, J.

J. Kushibiki and N. Chubachi, “Material characterization by line-focus-beam acoustic microscope,” Trans. Sonics Ultrason.32(2), 189–212 (1985).
[CrossRef]

Liu, S. G.

Mizuguchi, S.

Pechprasarn, S.

Raether, H.

E. Kretschmann and H. Raether, “Radiative decay of non radiative surface plasmons excited by light,” Zeitschrift Fur Naturforschung Part a-Astrophysik Physik Und Physikalische Chemie A, 23(12), 2135 (1968).

Roland, T.

F. Argoul, T. Roland, A. Fahys, L. Berguiga, and J. Elezgaray, “Uncovering phase maps from surface plasmon resonance images: Towards a sub-wavelength resolution,” C. R. Phys.8(8), 800–814 (2012).
[CrossRef]

See, C. W.

Somekh, M. G.

Velinov, T. S.

Zhang, B.

Zhang, J.

Zhang, S.

Appl. Opt.

C. R. Phys.

F. Argoul, T. Roland, A. Fahys, L. Berguiga, and J. Elezgaray, “Uncovering phase maps from surface plasmon resonance images: Towards a sub-wavelength resolution,” C. R. Phys.8(8), 800–814 (2012).
[CrossRef]

J. Microsc.

S. Pechprasarn and M. G. Somekh, “Surface plasmon microscopy: resolution, sensitivity and crosstalk,” J. Microsc.246(3), 287–297 (2012).
[CrossRef] [PubMed]

J. Opt. Soc. Am. B

Opt. Express

Opt. Lett.

Trans. Sonics Ultrason.

J. Kushibiki and N. Chubachi, “Material characterization by line-focus-beam acoustic microscope,” Trans. Sonics Ultrason.32(2), 189–212 (1985).
[CrossRef]

Zeitschrift Fur Naturforschung Part a-Astrophysik Physik Und Physikalische Chemie A

E. Kretschmann and H. Raether, “Radiative decay of non radiative surface plasmons excited by light,” Zeitschrift Fur Naturforschung Part a-Astrophysik Physik Und Physikalische Chemie A, 23(12), 2135 (1968).

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Figures (10)

Fig. 1
Fig. 1

(a) Simplified schematic showing operation of confocal microscope with SP excitation; (b) Schematic of optical system showing relationship between different planes in the system. The blue waveform indicates phase modulation in the back focal plane.

Fig. 2
Fig. 2

Simulated V(z) curves of uncoated (red) and sample coated with 10nm of indium tin oxide (blue) showing different periods of oscillations

Fig. 3
Fig. 3

(a) Pupil function distribution (red curve) and calculated reflection coefficient for p-incident polarization on an uncoated sample (blue curve); the vertical cyan lines represent the range of angles over which the phase stepping of the reference beam was imposed. (b) is the back focal plane (BFP) image by setting the adjacent pixels in antiphase on a phase-only SLM and (c) is the same with no modulation of the mid-frequencies.

Fig. 4
Fig. 4

Effect of phase stepping on relative phase of reference and plasmon beams, green line is the reference signal R, cyan line is the SP phasor, red line is the resultant signal V.

Fig. 5
Fig. 5

V(z) curves variations of bare gold obtained by shifting the phase of the reference in increments of 90 degrees. From lower to upper figures we have: zero phase shift (red), 90 degree phase shift (blue), 180 degree phase shift (black) and 270 degree phase shift (cyan). Successive curves are shifted by 0.1 units for clarity.

Fig. 6
Fig. 6

Experimetnal φ(z) obtained from four V(z) curves using the phase-stepping technique. The red curve refers to the unwrapped φ(z) of bare gold and the blue line is the fitted data, while the green curve refers to the ITO coated sample case and the black line is the linear fit.

Fig. 7
Fig. 7

(a) shows the method of measuring the ripple period measurement (b) shows 3rd order polynomial fit (black) to locate a minimum position for ripple period measurement; (c) shows regions on φ(z) and corresponding ripple positions.

Fig. 8
Fig. 8

(a) Mean standard deviation in degrees versus SNR level in dB for single ripple measurements and half ripple measurement for phase stepping. Solid black is for 1 ripple phase stepping measurement, dashed black for 1 ripple period measurement, dotted black for 1 ripple FFT measurement and solid blue for half ripple phase stepping measurement. (b) Mean standard deviation in degrees versus SNR level in dB for first three ripple measurements. Solid black curve is for 3 ripples phase stepping measurement, dashed black curve is for 3 ripples period measurement, dotted black for 3 ripples FFT measurement.

Fig. 9
Fig. 9

Probability density function (pdf) of variation from expected value for ½ ripple period phase stepping measurement (blue), 1 ripple period phase stepping measurement (green), 2 ripple periods phase stepping measurement (red) and 3 ripple periods phase stepping measurement (cyan). These results were simulated with the noise level corresponding to the experimental results shown in Fig. 6. The ½, 1, 2 and 3 ripples are equivalent to 375 nm, 750 nm, 1,500 nm and 2,250 nm in z defocus distance respectively.

Fig. 10
Fig. 10

(a) The |S| curves by using the direct method (add 0.1 in plot) and indirect methods; (b) Propagation attenuation comparison between the 29nm and 46nm thickness of gold layer; (c) Propagation attenuation comparison of |S| for different thickness of gold layer, the blue curve shows the direct method results and the red curve for the indirect results. The black curve represents the calculated value of attenuation for each layer thickness. The data from each measurement was fitted to a third order polynomial curve.

Tables (1)

Tables Icon

Table 1 Standard deviation (S.D.) of the measurement error for the defocus ranges presented in Fig. 9

Equations (7)

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Δ ϕ ref = 4πn λ Δz Δ ϕ plas = 4πn λ cos θ p Δz
Δϕ= 4πn λ ( 1cos θ p )Δz
Δ z p = λ 2n( 1cos θ p )
I n (z)= | R(z) | 2 + | S(z) | 2 +2| R(z) || S(z) |cos(φ(z)+ α n )
φ(z)=2kz(1cos( θ p ))+β
s slope =2k(1cos( θ p ))
SN R opticalsignal = (SN R electricalsignal ) 2 = μ 2 σ 2

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