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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 18, Iss. 7 — Mar. 29, 2010
  • pp: 7108–7120
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Gouy phase shift in nondiffracting Bessel beams

Paolo Martelli, Matteo Tacca, Alberto Gatto, Giorgio Moneta, and Mario Martinelli  »View Author Affiliations


Optics Express, Vol. 18, Issue 7, pp. 7108-7120 (2010)
http://dx.doi.org/10.1364/OE.18.007108


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Abstract

The results of a theoretical and experimental investigation of the Gouy effect in Bessel beams are presented. We point out that the peculiar feature of the Bessel beams of being nondiffracting is related to the accumulation of an extra axial phase shift (i.e., the Gouy phase shift) linearly dependent on the propagation distance. The constant spatial rate of variation of the Gouy phase shift is independent of the order of the Bessel beam, while it is a growing function of the transverse component of the angular spectrum wave-vectors, originated by the transverse confinement of the beam. A free-space Mach-Zehnder interferometer has been set-up for measuring the transverse intensity distribution of the interference between holographically-produced finite-aperture Bessel beams of order from zero up to three and a reference Gaussian beam, at a wavelength of 633 nm. The interference patterns have been registered for different propagation distances and show a spatial periodicity, in agreement with the expected period due to the linear increase of the Gouy phase shift of the realized Bessel beams.

© 2010 OSA

1. Introduction

More than one hundred years ago Louis George Gouy discovered that a spherical converging waves experiences an abrupt phase change of π when it passes through the focal region [1

1. L. G. Gouy, “Sur une proprieté nouvelle des ondes lumineuses,” Acad. Sci., Paris, C. R. 110, 1251–1253 (1890).

]. This phase anomaly explains the imaginary factor i in the Huygens’ integral, corresponding to a phase shift of π/2 acquired by the secondary wavelets diverging from each point of the primary incident wave-front [2

2. A. E. Siegman, Lasers (University Science Books, Mill Valley, CA, 1986).

]. In general the Gouy effect manifests itself as an additional axial phase shift acquired by any diffracting optical beam (hence characterized by a transverse spatial confinement) with respect to a reference on-axis plane wave. It was been also recognized that the Gouy effect can be seen as another example of topological or Berry’s phase [3

3. M. V. Berry, “Quantal phase factors accompanying adiabatic changes,” Proc. R. Soc. Lond. A Math. Phys. Sci. 392(1802), 45–57 (1984). [CrossRef]

5

5. D. Subbarao, “Topological phase in Gaussian beam optics,” Opt. Lett. 20(21), 2162–2164 (1995). [CrossRef] [PubMed]

].

It is well known that Hermite- and Laguerre-Gaussian beams, which are the modes of curved mirrors resonators with respective indexes (m,n) and (p,l), show a Gouy phase shift equal to (m+n+1) atan(z/zR) and (2p+l+1) atan(z/zR), respectively, where z R is the Rayleigh range [2

2. A. E. Siegman, Lasers (University Science Books, Mill Valley, CA, 1986).

,6

6. H. Kogelnik and T. Li, “Laser beams and resonators,” Appl. Opt. 5(10), 1550–1567 (1966). [CrossRef] [PubMed]

,7

7. B. E. A. Saleh, and M. C. Teich, Fundamentals of Photonics (John Wiley & Sons, Inc., 1991).

]. This axial phase shift adds to the usual phase term −kz, corresponding to an on-axis plane wave, and therefore the Gouy effect plays a fundamental role in determining the resonant frequencies of the laser cavities [6

6. H. Kogelnik and T. Li, “Laser beams and resonators,” Appl. Opt. 5(10), 1550–1567 (1966). [CrossRef] [PubMed]

,8

8. T. Ackermann, W. Grosse-Nobis, and G. L. Lippi, “The Gouy phase shift, the average phase lag of Fourier components of Hermite-Gaussian modes and their application to resonance conditions in optical cavities,” Opt. Commun. 189(1-3), 5–14 (2001). [CrossRef]

]. For the fundamental Gaussian mode the accumulated additional phase shift propagating from −∞ to + ∞ is π, and the maximum variation rate is at the beam waist. For higher-order modes the phase shift is higher, due to the moltiplicative factor depending on the mode indexes. Explicit measurements of the Gouy phase shift for Hermite- and Laguerre-Gaussian beams have been only recently reported [9

9. J. H. Chow, G. de Vine, M. B. Gray, and D. E. McClelland, “Measurement of gouy phase evolution by use of spatial mode interference,” Opt. Lett. 29(20), 2339–2341 (2004). [CrossRef] [PubMed]

,10

10. J. Hamazaki, Y. Mineta, K. Oka, and R. Morita, “Direct observation of Gouy phase shift in a propagating optical vortex,” Opt. Express 14(18), 8382–8392 (2006), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-14-18-8382. [CrossRef] [PubMed]

], confirming the theoretical previsions.

In this article we investigate the Gouy effect in nondiffracting Bessel beams. These beams were recognized by Durnin [11

11. J. Durnin, “Exact solutions for nondiffracting beams. I. The scalar theory,” J. Opt. Soc. Am. A 4(4), 651–654 (1987). [CrossRef]

] as solutions of the scalar wave equation having a transverse intensity distribution independent of the propagation distance. Actually the Durnin’s solutions are exact in infinite free-space, but they are not square integrable (i.e., the energy is infinite) and thus are not physically realizable. However, finite-aperture approximated Bessel beams was experimentally generated, possessing a very small diffraction spreading over significant distances [12

12. J. Durnin, J. J. Miceli Jr, and J. H. Eberly, “Diffraction-free beams,” Phys. Rev. Lett. 58(15), 1499–1501 (1987). [CrossRef] [PubMed]

15

15. J. Arlt and K. Dholakia, “Generation of high-order Bessel beams by use of an axicon,” Opt. Commun. 177(1-6), 297–301 (2000). [CrossRef]

]. This remarkable feature is attractive in applications requiring a large depth of field, such as long-range optical alignement, optical interconnections, optical manipulation and guiding of microscopic particles [16

16. J. Arlt, V. Garces-Chavez, W. Sibbett, and K. Dholakia, “Optical micromanipulation using a Bessel light beam,” Opt. Commun. 197(4-6), 239–245 (2001). [CrossRef]

18

18. V. Garcés-Chávez, D. McGloin, M. J. Padgett, W. Dultz, H. Schmitzer, and K. Dholakia, “Observation of the transfer of the local angular momentum density of a multiringed light beam to an optically trapped particle,” Phys. Rev. Lett. 91(9), 093602 (2003). [CrossRef] [PubMed]

].

The Bessel beams can be seen as a set of free-space propagation modes, hence characterized by a propagation constant β. These beams, although nondiffracting, present a transverse spatial confinement inducing a reduction of β, which is just coincident to the axial component of the angular spectrum wave-vectors, with respect to k. The Gouy extra axial phase shift is then (kβ)z and hence it is directly proportional to the propagation distance z. We report here the first experimental verification of this linear z-dependence of the Gouy phase shift in Bessel beams up to third order, by using an interferometric technique.

2. Theory

A monochromatic free-space scalar optical field, which is an eigenfunction of the translation operator along the propagation axis z, obeys the following general expression
ψ(x,y,z,t)=ut(x,y) exp(-iβzexp(iωt),
(1)
where the transverse field ut(x,y) is a solution of the transverse Helmholtz equation [7

7. B. E. A. Saleh, and M. C. Teich, Fundamentals of Photonics (John Wiley & Sons, Inc., 1991).

]
t2ut(x,y)+(k2β2) ut(x,y)=0,
(2)
with k=ω/c and t2=2/x2+2/y2. If β is a real constant, then Eq. (1) represents free-space propagation modes. In this condition the action of the propagation along z is simply the multiplication of the field by the phase term exp(iβz), where β represents the propagation constant of the mode, therefore the intensity I(x,y)=|ut(x,y)|2 is not dependent on z.

A well-known example of free-space propagation modes is given by the monochromatic plane waves
ψ(r,t)=Aexp[-i(krωt)]=A exp(ikxx) exp(ikyy) exp(ikzz) exp(iωt)
(3)
characterized by wave-vectors k=(kxkykz) that can assume any orientation and whose lengths are fixed to the value k=ω/c. In fact, by equating β to the axial component kz of the wave-vector, we can easily verify that the transverse field
ut(x,y)=A exp(-ikxxexp(-ikyy)
(4)
satisfies Eq. (2). The plane waves are infinite-energy nondiffracting beams with constant intensity. In this case the reduction of β with respect to k is simply due to the inclination of the wave-vector k with respect to the axis z. A change of reference framework, which aligns k to the axis z, makes β coincident with k.

In the following we point out that the Bessel beams are another set of nondiffracting free-space propagation modes, which show a transverse spatial confinement differently from plane waves. It is suitable to express the spatial dependence on the scalar field of Eq. (1) in cylindrical coordinates:
ψ(ρ,ϑ,z,t)=ut(ρ,ϑ) exp(-iβzexp(iωt),
(5)
and Eq. (2), i.e. the transverse Helmoltz equation, becomes

2utρ2+1ρutρ+1ρ22utϑ2+(k2β2) ut=0
(6)

α=k2β2>0.
(9)

Therefore the Bessel beams are described by the scalar field

ψ(r,t)=A Jl(αρ) exp(ilϑexp(-iβzexp(iωt) .
(10)

These beams propagate along z without any diffraction, although they present a transverse spatial confinement, which is tighter as α increases. For instance, the radius of the central spot of the zero-order Bessel beam is r02.405/α.

Now we can determine the Gouy phase shift ϕGouy for the Bessel beams, by evaluating the extra axial phase shift with respect to a reference plane wave propagating along z. We obtain from Eqs. (9) and (10), by means of straigthforward algebra:

ϕGouy(z)=(kβ)z=α2k+k2α2z.
(11)

The Gouy phase shift for the nondiffracting Bessel beams accumulates proportionally to the propagation distance z and it is not explicitly dependent on the order of the beam, differently from diffracting Hermite- and Laguerre-Gaussian beams. Moreover the Gouy shift is a growing function of the parameter α, which measures the spatial confinement.

A meaningful explanation of the physical origin of the Gouy effect is given in [21

21. S. Feng and H. G. Winful, “Physical origin of the Gouy phase shift,” Opt. Lett. 26(8), 485–487 (2001). [CrossRef]

]. The transverse spatial confinement, through the uncertainty principle, causes a transverse spreading of the angular spectrum wave-vectors and a reduction of the average axial component with respect to k, hence giving the Gouy phase shift. The Bessel beams can be obtained as superposition of plane waves with wave-vectors describing a cone around the axis z [22

22. G. Indebetouw, “Nondiffracting optical fields: some remarks on their analysis and synthesis,” J. Opt. Soc. Am. A 6(1), 150–152 (1989). [CrossRef]

,23

23. M. A. Porras, C. J. Zapata-Rodríguez, and I. Gonzalo, “Gouy wave modes: undistorted pulse focalization in a dispersive medium,” Opt. Lett. 32(22), 3287–3289 (2007). [CrossRef] [PubMed]

], as depicted in Fig. 1
Fig. 1 Cone of the angular spectrum wave-vectors generating a Bessel beam.
. All these vectors have the same axial component kz=β and also the same transverse component
kt=k2kz2=k2β2=α,
(12)
in agreement with the condition expressed by Eq. (9). In conclusion the parameter α, ruling the transverse field shaping and consequently the Gouy phase shift, is exactly the transverse component of the wave-vectors generating the Bessel beams.

3. Holographic generation of finite-aperture Bessel beams

The ideal Bessel beams have infinite energy, since the square modulus of the transverse field, that is |ut|2=Jl2(αρ), is not integrable over a plane orthogonal to the propagation axis. In our experiments we have realized approximated l th-order Bessel beams with finite transverse extent, by using suitable computer generated holograms (CGHs).

According to the Fresnel diffraction theory, it is possible to obtain approximated Bessel beams by modulating the optical field through a finite circular pupil with transmission function [13

13. A. Vasara, J. Turunen, and A. T. Friberg, “Realization of general nondiffracting beams with computer-generated holograms,” J. Opt. Soc. Am. A 6(11), 1748–1754 (1989). [CrossRef] [PubMed]

,24

24. J. A. Davis, E. Carcole, and D. M. Cottrell, “Intensity and phase measurements of nondiffracting beams generated with a magneto-optic spatial light modulator,” Appl. Opt. 35(4), 593–598 (1996). [CrossRef] [PubMed]

,25

25. C. Paterson and R. Smith, “Higher-order Bessel waves produced by axicon-type computer-generated holograms,” Opt. Commun. 124(1-2), 121–130 (1996). [CrossRef]

]
tl(ρ,ϑ)={  exp(ilϑ) exp(i 2πρρ0)                  if   ρD  0                                                        if  ρ>D,
(13)
where D is the diameter of the pupil aperture and ρ0 is a characteristic length representing a scale factor of the beam size. This transmission function, realizable as phase-only hologram, allows for reproducing finite-aperture beams, which are substantially nondiffracting up to the maximum distance Lmax=ρ0D/λ and approximate ideal Bessel beams of size defined by substituting
α=2πρ0
(14)
in the field expression of Eq. (10).

By means of the carrier-frequency method [13

13. A. Vasara, J. Turunen, and A. T. Friberg, “Realization of general nondiffracting beams with computer-generated holograms,” J. Opt. Soc. Am. A 6(11), 1748–1754 (1989). [CrossRef] [PubMed]

,26

26. W.-H. Lee, “Computer-generated holograms,” in Progress in Optics XVI, E. Wolf, ed. (North-Holland, Amsterdam, 1978).

], it is possible to encode tl(ρ,ϑ) into the amplitude transmission function
Tl(ρ,ϑ)={   12 [1+cos(2πνρsinϑ+lϑ2πρρ0)]                  if   ρD   0                                                                        if  ρ>D
(15)
obtained by phase-modulating a carrier of spatial frequency ν (in the y direction) with the phase term of tl(ρ,ϑ). The transmission Tl(ρ,ϑ) represents a cosinusoidal amplitude grating, with spatial period of 1/ν, which is distorted by the phase of tl(ρ,ϑ) in order to encode the needed phase information into an off-axis amplitude hologram. The feature of Tl(ρ,ϑ) is to reproduce a finite-aperture l th-order Bessel beam in the transmitted first order of diffraction, when illuminated by a plane wave.

For simplifiying the realization of the hologram, it is possible to obtain good reconstructions also by means of binary-amplitude coding, since the main effect of the binarization is the redistribution of the energy among the various hologram diffraction orders. In this case Tl(ρ,ϑ) is replaced by the binarized transmission function

Tl(B)(ρ,ϑ)={   1         if   1212 [1+cos(2πνρsinϑ+lϑ2πρρ0)]1   and   ρD 0         if   012 [1+cos(2πνρsinϑ+lϑ2πρρ0)]12   or   ρ>D.
(16)

In this work we have fabricated four binary-amplitude off-axis CGHs with transmission functions Tl(B)(ρ,ϑ), shown in Fig. 2
Fig. 2 Transmission functions of the binary-amplitude off-axis CGHs for obtaining finite-aperture l th-order Bessel beams: (a) l = 0; (b) l = 1; (c) l = 2; (d) l = 3. The black region corresponds to a transmission equal to zero.
, to reproduce Bessel beams of order l respectively from 0 to 3. In particular, each CGH has been realized by plotting the corresponding bidimensional transmission pattern with a laser printer and photoreducing it on Ilford Pan film. All these holograms have the same parameters ν=5 mm−1, D=5 mm and ρ0=0.25 mm.

Figure 3
Fig. 3 Measured intensity distribution of the finite-aperture l th-order Bessel beams reproduced by the realized binary-amplitude off-axis CGHs: (a) l = 0; (b) l = 1; (c) l = 2; (d) l = 3.
reports some measured intensity distributions of the finite-aperture Bessel beams obtained by illuminating the binary CGHs with an expanded He-Ne laser beam (wavelength λ=633 nm). The distributions have been acquired by a CCD camera collecting the first diffraction order at a distance of 60 cm from each hologram. This distance is sufficient for spatially separating the desired first diffraction order from the order zero and is less than the maximum nondiffracting distance Lmax, which in our experimental conditions is about 2 m.

4. Experimental verification of the Gouy phase shift in Bessel beams

For observing the Gouy phase shift of the Bessel beams, we have set-up the free-space Mach-Zehnder interferometer schematically shown in Fig. 4
Fig. 4 Scheme of the interferometric set-up for observing the Gouy phase shift of Bessel beams.
and we have acquired the interference patterns between the holographically-produced l th-order Bessel beams, with l varying from zero to three, and a reference Gaussian beam. More in detail, a Gaussian beam with wavelength of 633 nm and spot size of about 0.3 mm is emitted by a He-Ne laser source and then split by a 50/50 cube beam splitter (BS) in two beams propagating respectively in the two different arms of the interferometer. The beam in the first arm is just attenuated, to equalize the optical powers of the interfering beams, and remains Gaussian. The beam in the second arm is expanded of a factor 8 by a two-lens system and goes through the proper CGH for producing the required l th-order Bessel beam. The unwanted diffraction order μ=0 of the CGH is blocked by an absorber, while the desired order μ=1 (that is the Bessel beam) is aligned so as to interfere, after the output 50/50 BS, with the reference Gaussian beam of the other arm. Finally the transverse intensity distribution of the interference between the Bessel and Gauss beams has been acquired by a CCD camera, placed over a motorized stage movable along the propagation direction z.

In the following we give an analytical expression of the expected interference intensity as a function of the cylindrical coordinates (ρ,ϑ,z). The finite-aperture l th-order Bessel beam reproduced by the CGH is an approximation of the ideal nondiffracting beam characterized by the field
uBessel(ρ,ϑ,z)=AB Jl(2πρρ0) exp(ilϑexp(-iβz),
(17)
according to Eqs. (10) and (14). The propagation constant β, from Eq. (9), is given by

β=k2α2=k1(α/k)2=k1(λ/ρ0)2.
(18)

Since λ<<ρ0 and hence α<<k, we can express β as

βk(1α22k2)=kα22k=kπλρ02.
(19)

In this case the Gouy phase shift of Eq. (11) can be approximated by

ϕGouy(z)α22kz=πλρ02z.
(20)

On the other hand, the field of the reference Gaussian beam is [2

2. A. E. Siegman, Lasers (University Science Books, Mill Valley, CA, 1986).

,6

6. H. Kogelnik and T. Li, “Laser beams and resonators,” Appl. Opt. 5(10), 1550–1567 (1966). [CrossRef] [PubMed]

,7

7. B. E. A. Saleh, and M. C. Teich, Fundamentals of Photonics (John Wiley & Sons, Inc., 1991).

]
uGauss(ρ,z)=AGw0w(z) exp[ρ2w2(z)] exp[ikz+iarctan(zzR)ikρ22R(z)],
(21)
where w(z)=w0[1+(z/zR)2] 1/2 is the spot size, R(z)=z [1+(zR/z)2] is the wave-front curvature radius and zR=πw02/λ is the Rayleigh range. The intensity of the interference between the Bessel beam of Eq. (17), considering the expression of β given by Eq. (19), and the Gaussian beam of Eq. (21) is then
I(ρ,ϑ,z)=|AB|2Jl2(2πρρ0)+|AG|2w02w2(z) exp[2ρ2w2(z)]+
+2|ABAGJl(2πρρ0)|w0w(z) exp[ρ2w2(z)] cos[ζ(ρ,ϑ,z)],
(22)
where the phase difference between the Bessel and Gaussian beams, giving the argument of the cosine in the beating term, is

ζ(ρ,ϑ,z)=lϑ+πλρ02zarctan(zzR)+kρ22R(z)+ϕ0.
(23)

Λ=2π (dϕGouydz)18π2α2λ=2ρ02λ.
(24)

Actually the reference beam used in the interferometric measure is not a plane wave, but a Gaussian beam, which is diffracting and perturbs the periodicity of the interference pattern. For evaluating the entity of such a perturbation we calculate the variation of ζ due to the two Gaussian phase contributions in Eq. (23), for a variation of the propagation distance z equal to Λ. The initial distance is z0=1.4 m, corresponding to the length of the propagation path of the reference Gaussian beam between its waist (with spot size w0=0.3 mm) and the initial position of the CCD camera. At the final distance z=z0+Λ the variation of the Gouy phase shift of the Gaussian beam is 2.1°, yielding a relative error of 0.58% in the evaluation of ζ, since the corresponding variation of the Gouy phase shift of the Bessel beam is 360°. Moreover, the contribution to ζ due to the wave-front curvature of the Gaussian beam is dependent on the radial coordinate ρ. If we evaluate the perturbation of ζ, induced by the two Gaussian phase contributions, in the radial position ρp of the intensity peak of the Bessel beams with order l from 0 to 3 (resulting in ρp/ρ0=0, 0.293, 0.486 and 0.669, respectively), then we obtain an overall relative error of 0.58%, 0.60%, 0.66% and 0.73%, respectively. So we have shown that the expected perturbation of the ideally periodical interference pattern, due to the diffracting Gaussian reference beam, is very small in the considered experimental conditions.

In Fig. 5
Fig. 5 Transverse intensity distributions of the interference between l th-order Bessel beams (with l from 0 to 3) and a reference Gaussian beam, calculated at the initial position z 0 (first column), at z 0 + Λ/2 (second column), and at z 0 + Λ (third column).
we report the transverse intensity distributions of the interference between the l th-order Bessel beams and the reference Gaussian beam, calculated at different propagation distances z=z0+d by using Eqs. (22) and (23), considering the actual experimental values of the parameters. The interference patterns shown in the first column are calculated at the initial position z0. Then the position is increased by a quantity d, obtaining the patterns shown in the second and third column, respectively after the increments d=Λ/2 and d=Λ. We can see that the patterns remains practically unchanged after the ideally calculated period Λ for all Bessel beams considered, having orders from 0 to 3.

In the case of zero-order Bessel beam (i.e., the first raw of Fig. 5) the interference patterns are circularly symmetric and show a series of bright concentric rings alternated by dark concentric rings. After a semi-period Λ/2 the Gouy phase shift of the Bessel beam increments of π and consequently the bright and dark rings of the interference pattern mutually exchange. On the other hand, after a period Λ the Gouy phase shift increment is 2π and the resulting interference pattern is practically identical to the initial pattern.

In the case of higher-order Bessel beams the interference patterns are invariant for rotations being integer multiples of 2π/l, due to the angular phase term lϑ in Eq. (23). The intensity maxima are located on a series of concentric rings: each one of these rings contains exactly l maxima, which are equally spaced and alternated by l minima. The Gouy phase shift of the l th-order Bessel beams varies in the propagation along z with constant rate, causing a uniform rotation of the intensity with angular rate 2π/(lΛ). After a semi-period Λ/2 the interference pattern rotates of π/l and the intensity maxima and minima mutually exchange, while after a period Λ the pattern rotates of 2π/l and returns coincident to the initial pattern, apart from a slight perturbation of the pattern periodicity due to the Gaussian reference beam. The only relevant effect of employing a Gaussian reference beam is the growing shift of the angular position of the maxima (minima) in the outer rings, giving spiral-like interference patterns. In fact, considering an ideal plane wave as reference beam, the maxima and the minima should be alternated in radial direction, since the consecutive intensity maxima rings of the Bessel beams have a phase difference of π. Actually the phase term due to the wave-front curvature of the Gaussian beam gives a contribution to ζ proportional to the square of the radial distance and consequently the maxima (minima) of the interference pattern acquires an additional angular shift proportional to ρ 2.

We point out that the interference patterns of Fig. 5 have been calculated considering ideal Bessel beams. Actually in the experiments we have used finite-aperture Bessel beams obtained by means of CGHs. However, the Bessel beams propagate from the respective CGHs to the CCD camera for a maximum distance of about 1.1 m, at the final position z=z0+Λ, that is less than the maximum nondiffracting length Lmax=ρ0D/λ2 m. Therefore the CGH-realized Bessel beams are a good approximation of the ideal Bessel beams whose field is described by Eq. (17).

The interference patterns measured at different distances, incrementing the initial position z 0 of the CCD camera by the quantity d, confirms the expected periodical behavior due to the linear accumulation of the Gouy phase shift of the CGH-produced Bessel beams. As shown in Fig. 6
Fig. 6 Transverse intensity distributions of the interference between l th-order Bessel beams (with l from 0 to 3) and a reference Gaussian beam, acquired by a CCD camera at the initial position z 0 (first column), at z 0 + Λ/2 (second column), and at z 0 + Λ (third column).
, the registered patterns are in good agreement with the simulated ones, apart from a phase offset, and recur after Λ. In particular, the measured pattern appears circularly symmetric and pulsates cyclically for l=0, inverting maxima with minima after Λ/2, while it shows l bright spots in the inner ring and rotates uniformly for l from 1 to 3, as z increases.

5. Conclusion

We have investigated both theoretically and experimentally the Gouy effect in Bessel. Such beams possess the very remarkable feature of being nondiffracting: in this case the Gouy effect manifests itself as a reduction of the propagation constant β with respect to the length k of the wave-vector of a plane wave with same direction and wavelength. Therefore the Gouy extra axial phase shift accumulates linearly as the propagation distance increases, with a constant rate equal to the difference between k and β. This rate is independent of the order of the Bessel beam and depends only on the wavelength and on the transverse component α of the angular spectrum wave-vectors, which describe a cone around the propagation axis. In particular the Gouy phase shift is a growing function of α, according to the physical interpretation of the Gouy effect as originated by the transverse confinement of the beam. In fact the angular spectrum spreading, induced by the spatial confinement, causes an increase of α and hence a reduction of β, which is exactly the axial component of the angular spectrum wave-vectors.

For obtaining an experimental characterization of the Gouy effect in Bessel beams, we have realized finite-aperture Bessel beams of order from zero up to three, by means of off-axis binary-amplitude CGHs. We have measured, at different propagation distances, the transverse intensity distribution of the interference between each CGH-produced Bessel beam and a reference Gaussian beam. The measured interference patterns are in good agreement with the expected patterns. The linear dependence of the Gouy phase shift on the propagation distance, which is a remarkable property of the nondiffracting Bessel beams (differently from diffracting beams, as the well known Hermite- and Laguerre-Gauss beams), implies that the calculated interference patterns must have a spatial periodicity depending on the wavelength and on the parameter α. Our experiments show that the patterns actually recur after the expected period, therefore providing a direct observation of the Gouy effect in nondiffracting Bessel beams.

References and links

1.

L. G. Gouy, “Sur une proprieté nouvelle des ondes lumineuses,” Acad. Sci., Paris, C. R. 110, 1251–1253 (1890).

2.

A. E. Siegman, Lasers (University Science Books, Mill Valley, CA, 1986).

3.

M. V. Berry, “Quantal phase factors accompanying adiabatic changes,” Proc. R. Soc. Lond. A Math. Phys. Sci. 392(1802), 45–57 (1984). [CrossRef]

4.

R. Simon and N. Mukunda, “Bargmann invariant and the geometry of the Güoy effect,” Phys. Rev. Lett. 70(7), 880–883 (1993). [CrossRef] [PubMed]

5.

D. Subbarao, “Topological phase in Gaussian beam optics,” Opt. Lett. 20(21), 2162–2164 (1995). [CrossRef] [PubMed]

6.

H. Kogelnik and T. Li, “Laser beams and resonators,” Appl. Opt. 5(10), 1550–1567 (1966). [CrossRef] [PubMed]

7.

B. E. A. Saleh, and M. C. Teich, Fundamentals of Photonics (John Wiley & Sons, Inc., 1991).

8.

T. Ackermann, W. Grosse-Nobis, and G. L. Lippi, “The Gouy phase shift, the average phase lag of Fourier components of Hermite-Gaussian modes and their application to resonance conditions in optical cavities,” Opt. Commun. 189(1-3), 5–14 (2001). [CrossRef]

9.

J. H. Chow, G. de Vine, M. B. Gray, and D. E. McClelland, “Measurement of gouy phase evolution by use of spatial mode interference,” Opt. Lett. 29(20), 2339–2341 (2004). [CrossRef] [PubMed]

10.

J. Hamazaki, Y. Mineta, K. Oka, and R. Morita, “Direct observation of Gouy phase shift in a propagating optical vortex,” Opt. Express 14(18), 8382–8392 (2006), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-14-18-8382. [CrossRef] [PubMed]

11.

J. Durnin, “Exact solutions for nondiffracting beams. I. The scalar theory,” J. Opt. Soc. Am. A 4(4), 651–654 (1987). [CrossRef]

12.

J. Durnin, J. J. Miceli Jr, and J. H. Eberly, “Diffraction-free beams,” Phys. Rev. Lett. 58(15), 1499–1501 (1987). [CrossRef] [PubMed]

13.

A. Vasara, J. Turunen, and A. T. Friberg, “Realization of general nondiffracting beams with computer-generated holograms,” J. Opt. Soc. Am. A 6(11), 1748–1754 (1989). [CrossRef] [PubMed]

14.

A. J. Cox and D. C. Dibble, “Nondiffracting beam from a spatially filtered Fabry-Perot resonator,” J. Opt. Soc. Am. A 9(2), 282–286 (1992). [CrossRef]

15.

J. Arlt and K. Dholakia, “Generation of high-order Bessel beams by use of an axicon,” Opt. Commun. 177(1-6), 297–301 (2000). [CrossRef]

16.

J. Arlt, V. Garces-Chavez, W. Sibbett, and K. Dholakia, “Optical micromanipulation using a Bessel light beam,” Opt. Commun. 197(4-6), 239–245 (2001). [CrossRef]

17.

S. A. Tatarkova, W. Sibbett, and K. Dholakia, “Brownian particle in an optical potential of the washboard type,” Phys. Rev. Lett. 91(3), 038101 (2003). [CrossRef] [PubMed]

18.

V. Garcés-Chávez, D. McGloin, M. J. Padgett, W. Dultz, H. Schmitzer, and K. Dholakia, “Observation of the transfer of the local angular momentum density of a multiringed light beam to an optically trapped particle,” Phys. Rev. Lett. 91(9), 093602 (2003). [CrossRef] [PubMed]

19.

G. B. Arfken, and H. J. Weber, Mathematical Methods for Physicists (Harcourt/Academic Press, 5th Ed., 2001).

20.

N. N. Lebedev, Special Functions and their Applications (Dover Publications, Inc., New York, 1972).

21.

S. Feng and H. G. Winful, “Physical origin of the Gouy phase shift,” Opt. Lett. 26(8), 485–487 (2001). [CrossRef]

22.

G. Indebetouw, “Nondiffracting optical fields: some remarks on their analysis and synthesis,” J. Opt. Soc. Am. A 6(1), 150–152 (1989). [CrossRef]

23.

M. A. Porras, C. J. Zapata-Rodríguez, and I. Gonzalo, “Gouy wave modes: undistorted pulse focalization in a dispersive medium,” Opt. Lett. 32(22), 3287–3289 (2007). [CrossRef] [PubMed]

24.

J. A. Davis, E. Carcole, and D. M. Cottrell, “Intensity and phase measurements of nondiffracting beams generated with a magneto-optic spatial light modulator,” Appl. Opt. 35(4), 593–598 (1996). [CrossRef] [PubMed]

25.

C. Paterson and R. Smith, “Higher-order Bessel waves produced by axicon-type computer-generated holograms,” Opt. Commun. 124(1-2), 121–130 (1996). [CrossRef]

26.

W.-H. Lee, “Computer-generated holograms,” in Progress in Optics XVI, E. Wolf, ed. (North-Holland, Amsterdam, 1978).

OCIS Codes
(260.1960) Physical optics : Diffraction theory
(350.5030) Other areas of optics : Phase

ToC Category:
Physical Optics

History
Original Manuscript: December 16, 2009
Manuscript Accepted: February 9, 2010
Published: March 23, 2010

Citation
Paolo Martelli, Matteo Tacca, Alberto Gatto, Giorgio Moneta, and Mario Martinelli, "Gouy phase shift in nondiffracting Bessel beams," Opt. Express 18, 7108-7120 (2010)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-18-7-7108


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References

  1. L. G. Gouy, “Sur une proprieté nouvelle des ondes lumineuses,” Acad. Sci., Paris, C. R. 110, 1251–1253 (1890).
  2. A. E. Siegman, Lasers (University Science Books, Mill Valley, CA, 1986).
  3. M. V. Berry, “Quantal phase factors accompanying adiabatic changes,” Proc. R. Soc. Lond. A Math. Phys. Sci. 392(1802), 45–57 (1984). [CrossRef]
  4. R. Simon and N. Mukunda, “Bargmann invariant and the geometry of the Güoy effect,” Phys. Rev. Lett. 70(7), 880–883 (1993). [CrossRef] [PubMed]
  5. D. Subbarao, “Topological phase in Gaussian beam optics,” Opt. Lett. 20(21), 2162–2164 (1995). [CrossRef] [PubMed]
  6. H. Kogelnik and T. Li, “Laser beams and resonators,” Appl. Opt. 5(10), 1550–1567 (1966). [CrossRef] [PubMed]
  7. B. E. A. Saleh, and M. C. Teich, Fundamentals of Photonics (John Wiley & Sons, Inc., 1991).
  8. T. Ackermann, W. Grosse-Nobis, and G. L. Lippi, “The Gouy phase shift, the average phase lag of Fourier components of Hermite-Gaussian modes and their application to resonance conditions in optical cavities,” Opt. Commun. 189(1-3), 5–14 (2001). [CrossRef]
  9. J. H. Chow, G. de Vine, M. B. Gray, and D. E. McClelland, “Measurement of gouy phase evolution by use of spatial mode interference,” Opt. Lett. 29(20), 2339–2341 (2004). [CrossRef] [PubMed]
  10. J. Hamazaki, Y. Mineta, K. Oka, and R. Morita, “Direct observation of Gouy phase shift in a propagating optical vortex,” Opt. Express 14(18), 8382–8392 (2006), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-14-18-8382 . [CrossRef] [PubMed]
  11. J. Durnin, “Exact solutions for nondiffracting beams. I. The scalar theory,” J. Opt. Soc. Am. A 4(4), 651–654 (1987). [CrossRef]
  12. J. Durnin, J. J. Miceli, and J. H. Eberly, “Diffraction-free beams,” Phys. Rev. Lett. 58(15), 1499–1501 (1987). [CrossRef] [PubMed]
  13. A. Vasara, J. Turunen, and A. T. Friberg, “Realization of general nondiffracting beams with computer-generated holograms,” J. Opt. Soc. Am. A 6(11), 1748–1754 (1989). [CrossRef] [PubMed]
  14. A. J. Cox and D. C. Dibble, “Nondiffracting beam from a spatially filtered Fabry-Perot resonator,” J. Opt. Soc. Am. A 9(2), 282–286 (1992). [CrossRef]
  15. J. Arlt and K. Dholakia, “Generation of high-order Bessel beams by use of an axicon,” Opt. Commun. 177(1-6), 297–301 (2000). [CrossRef]
  16. J. Arlt, V. Garces-Chavez, W. Sibbett, and K. Dholakia, “Optical micromanipulation using a Bessel light beam,” Opt. Commun. 197(4-6), 239–245 (2001). [CrossRef]
  17. S. A. Tatarkova, W. Sibbett, and K. Dholakia, “Brownian particle in an optical potential of the washboard type,” Phys. Rev. Lett. 91(3), 038101 (2003). [CrossRef] [PubMed]
  18. V. Garcés-Chávez, D. McGloin, M. J. Padgett, W. Dultz, H. Schmitzer, and K. Dholakia, “Observation of the transfer of the local angular momentum density of a multiringed light beam to an optically trapped particle,” Phys. Rev. Lett. 91(9), 093602 (2003). [CrossRef] [PubMed]
  19. G. B. Arfken, and H. J. Weber, Mathematical Methods for Physicists (Harcourt/Academic Press, 5th Ed., 2001).
  20. N. N. Lebedev, Special Functions and their Applications (Dover Publications, Inc., New York, 1972).
  21. S. Feng and H. G. Winful, “Physical origin of the Gouy phase shift,” Opt. Lett. 26(8), 485–487 (2001). [CrossRef]
  22. G. Indebetouw, “Nondiffracting optical fields: some remarks on their analysis and synthesis,” J. Opt. Soc. Am. A 6(1), 150–152 (1989). [CrossRef]
  23. M. A. Porras, C. J. Zapata-Rodríguez, and I. Gonzalo, “Gouy wave modes: undistorted pulse focalization in a dispersive medium,” Opt. Lett. 32(22), 3287–3289 (2007). [CrossRef] [PubMed]
  24. J. A. Davis, E. Carcole, and D. M. Cottrell, “Intensity and phase measurements of nondiffracting beams generated with a magneto-optic spatial light modulator,” Appl. Opt. 35(4), 593–598 (1996). [CrossRef] [PubMed]
  25. C. Paterson and R. Smith, “Higher-order Bessel waves produced by axicon-type computer-generated holograms,” Opt. Commun. 124(1-2), 121–130 (1996). [CrossRef]
  26. W.-H. Lee, "Computer-generated holograms," in Progress in Optics XVI, E. Wolf, ed., (North-Holland, Amsterdam, 1978).

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