Jones calculus

Inoptics,polarized lightcan be described using theJones calculus,invented byR. C. Jonesin 1941. Polarized light is represented by aJones vector,and linear optical elements are represented byJonesmatrices.When light crosses an optical element the resulting polarization of the emerging light is found by taking the product of the Jones matrix of the optical element and the Jones vector of the incident light. Note that Jones calculus is only applicable to light that is already fully polarized. Light which is randomly polarized, partially polarized, or incoherent must be treated usingMueller calculus.

Jones vector

The Jones vector describes the polarization of light in free space or anotherhomogeneousisotropicnon-attenuatingmedium, where the light can be properly described astransverse waves.Suppose that a monochromaticplane waveof light is travelling in the positivez-direction, with angular frequencyωandwave vectork= (0,0,k), where thewavenumberk=ω/c.Then the electric and magnetic fieldsEandHare orthogonal tokat each point; they both lie in the plane "transverse" to the direction of motion. Furthermore,His determined fromEby 90-degree rotation and a fixed multiplier depending on thewave impedanceof the medium. So the polarization of the light can be determined by studyingE.The complex amplitude ofEis written:

${\begin{pmatrix}E_{x}(t)\\E_{y}(t)\\0\end{pmatrix}}={\begin{pmatrix}E_{0x}e^{i(kz-\ Omega t+\phi _{x})}\\E_{0y}e^{i(kz-\ Omega t+\phi _{y})}\\0\end{pmatrix}}={\begin{pmatrix}E_{0x}e^{i\phi _{x}}\\E_{0y}e^{i\phi _{y}}\\0\end{pmatrix}}e^{i(kz-\ Omega t)}.$

Note that the physicalEfield is the real part of this vector; the complex multiplier serves up the phase information. Here$i$is theimaginary unitwith$i^{2}=-1$.

The Jones vector is

${\begin{pmatrix}E_{0x}e^{i\phi _{x}}\\E_{0y}e^{i\phi _{y}}\end{pmatrix}}.$

Thus, the Jones vector represents the amplitude and phase of the electric field in thexandydirections.

The sum of the squares of the absolute values of the two components of Jones vectors is proportional to the intensity of light. It is common to normalize it to 1 at the starting point of calculation for simplification. It is also common to constrain the first component of the Jones vectors to be areal number.This discards the overall phase information that would be needed for calculation ofinterferencewith other beams.

Note that all Jones vectors and matrices in this article employ the convention that the phase of the light wave is given by$\phi =kz-\ Omega t$,a convention used by Hecht. Under this convention, increase in$\phi _{x}$(or$\phi _{y}$) indicates retardation (delay) in phase, while decrease indicates advance in phase. For example, a Jones vectors component of$i$($=e^{i\pi /2}$) indicates retardation by$\pi /2$(or 90 degree) compared to 1 ($=e^{0}$). Collett uses the opposite definition for the phase ($\phi =\ Omega t-kz$). Also, Collet and Jones follow different conventions for the definitions of handedness of circular polarization. Jones' convention is called: "From the point of view of the receiver", while Collett's convention is called: "From the point of view of the source." The reader should be wary of the choice of convention when consulting references on the Jones calculus.

The following table gives the 6 common examples of normalized Jones vectors.

Polarization	Jones vector	Typicalketnotation
Linear polarized in thexdirection Typically called "horizontal"	${\begin{pmatrix}1\\0\end{pmatrix}}$	$|H\rangle$
Linear polarized in theydirection Typically called "vertical"	${\begin{pmatrix}0\\1\end{pmatrix}}$	$|V\rangle$
Linear polarized at 45° from thexaxis Typically called "diagonal" L+45	${\frac {1}{\sqrt {2}}}{\begin{pmatrix}1\\1\end{pmatrix}}$	$|D\rangle ={\frac {1}{\sqrt {2}}}{\big (}|H\rangle +|V\rangle {\big )}$
Linear polarized at −45° from thexaxis Typically called "anti-diagonal" L−45	${\frac {1}{\sqrt {2}}}{\begin{pmatrix}1\\-1\end{pmatrix}}$	$|A\rangle ={\frac {1}{\sqrt {2}}}{\big (}|H\rangle -|V\rangle {\big )}$
Right-hand circular polarized Typically called "RCP" or "RHCP"	${\frac {1}{\sqrt {2}}}{\begin{pmatrix}1\\-i\end{pmatrix}}$	$|R\rangle ={\frac {1}{\sqrt {2}}}{\big (}|H\rangle -i|V\rangle {\big )}$
Left-hand circular polarized Typically called "LCP" or "LHCP"	${\frac {1}{\sqrt {2}}}{\begin{pmatrix}1\\+i\end{pmatrix}}$	$|L\rangle ={\frac {1}{\sqrt {2}}}{\big (}|H\rangle +i|V\rangle {\big )}$

A general vector that points to any place on the surface is written as aket$|\psi \rangle$.When employing thePoincaré sphere(also known as theBloch sphere), the basis kets ($|0\rangle$and$|1\rangle$) must be assigned to opposing (antipodal) pairs of the kets listed above. For example, one might assign$|0\rangle$=$|H\rangle$and$|1\rangle$=$|V\rangle$.These assignments are arbitrary. Opposing pairs are

• $|H\rangle$and$|V\rangle$
• $|D\rangle$and$|A\rangle$
• $|R\rangle$and$|L\rangle$

The polarization of any point not equal to$|R\rangle$or$|L\rangle$and not on the circle that passes through$|H\rangle,|D\rangle,|V\rangle,|A\rangle$is known aselliptical polarization.

Jones matrices

The Jones matrices are operators that act on the Jones vectors defined above. These matrices are implemented by various optical elements such as lenses, beam splitters, mirrors, etc. Each matrix represents projection onto a one-dimensional complex subspace of the Jones vectors. The following table gives examples of Jones matrices for polarizers:

Optical element	Jones matrix
Linearpolarizerwith axis of transmission horizontal	${\begin{pmatrix}1&0\\0&0\end{pmatrix}}$
Linear polarizer with axis of transmission vertical	${\begin{pmatrix}0&0\\0&1\end{pmatrix}}$
Linear polarizer with axis of transmission at ±45° with the horizontal	${\frac {1}{2}}{\begin{pmatrix}1&\pm 1\\\pm 1&1\end{pmatrix}}$
Linear polarizer with axis of transmission angle$\theta$from the horizontal	${\begin{pmatrix}\cos ^{2}(\theta )&\cos(\theta )\sin(\theta )\\\cos(\theta )\sin(\theta )&\sin ^{2}(\theta )\end{pmatrix}}$
Right circular polarizer	${\frac {1}{2}}{\begin{pmatrix}1&i\\-i&1\end{pmatrix}}$
Left circular polarizer	${\frac {1}{2}}{\begin{pmatrix}1&-i\\i&1\end{pmatrix}}$

Phase retarders

A phase retarder is an optical element that produces a phase difference between two orthogonal polarization components of a monochromatic polarized beam of light.Mathematically, usingketsto represent Jones vectors, this means that the action of a phase retarder is to transform light with polarization

$|P\rangle =c_{1}|1\rangle +c_{2}|2\rangle$

to

$|P'\rangle =c_{1}{\rm {e}}^{i\eta /2}|1\rangle +c_{2}{\rm {e}}^{-i\eta /2}|2\rangle$

where$|1\rangle,|2\rangle$are orthogonal polarization components (i.e.$\langle 1|2\rangle =0$) that are determined by the physical nature of the phase retarder. In general, the orthogonal components could be any two basis vectors. For example, the action of the circular phase retarder is such that

$|1\rangle ={\frac {1}{\sqrt {2}}}{\begin{pmatrix}1\\-i\end{pmatrix}}\qquad {\text{ and }}\qquad |2\rangle ={\frac {1}{\sqrt {2}}}{\begin{pmatrix}1\\i\end{pmatrix}}$

However, linear phase retarders, for which$|1\rangle,|2\rangle$are linear polarizations, are more commonly encountered in discussion and in practice. In fact, sometimes the term "phase retarder" is used to refer specifically to linear phase retarders.

Linear phase retarders are usually made out ofbirefringentuniaxial crystalssuch ascalcite,MgF₂orquartz.Plates made of these materials for this purpose are referred to aswaveplates.Uniaxial crystals have one crystal axis that is different from the other two crystal axes (i.e.,n_i≠n_j=n_k). This unique axis is called the extraordinary axis and is also referred to as theoptic axis.An optic axis can be the fast or the slow axis for the crystal depending on the crystal at hand. Light travels with a higher phase velocity along an axis that has the smallestrefractive indexand this axis is called the fast axis. Similarly, an axis which has the largest refractive index is called a slow axis since thephase velocityof light is the lowest along this axis. "Negative" uniaxial crystals (e.g.,calciteCaCO₃,sapphireAl₂O₃) haven_e<n_oso for these crystals, the extraordinary axis (optic axis) is the fast axis, whereas for "positive" uniaxial crystals (e.g.,quartzSiO₂,magnesium fluorideMgF₂,rutileTiO₂),n_e>n_oand thus the extraordinary axis (optic axis) is the slow axis. Other commercially available linear phase retarders exist and are used in more specialized applications. TheFresnel rhombsis one such alternative.

Any linear phase retarder with its fast axis defined as the x- or y-axis has zero off-diagonal terms and thus can be conveniently expressed as

${\begin{pmatrix}{\rm {e}}^{i\phi _{x}}&0\\0&{\rm {e}}^{i\phi _{y}}\end{pmatrix}}$

where$\phi _{x}$and$\phi _{y}$are the phase offsets of the electric fields in$x$and$y$directions respectively. In the phase convention$\phi =kz-\ Omega t$,define the relative phase between the two waves as$\epsilon =\phi _{y}-\phi _{x}$.Then a positive$\epsilon$(i.e.$\phi _{y}$>$\phi _{x}$) means that$E_{y}$doesn't attain the same value as$E_{x}$until a later time, i.e.$E_{x}$leads$E_{y}$.Similarly, if$\epsilon <0$,then$E_{y}$leads$E_{x}$.

For example, if the fast axis of a quarter waveplate is horizontal, then the phase velocity along the horizontal direction is ahead of the vertical direction i.e.,$E_{x}$leads$E_{y}$.Thus,$\phi _{x}<\phi _{y}$which for a quarter waveplate yields$\phi _{y}=\phi _{x}+\pi /2$.

In the opposite convention$\phi =\ Omega t-kz$,define the relative phase as$\epsilon =\phi _{x}-\phi _{y}$.Then$\epsilon >0$means that$E_{y}$doesn't attain the same value as$E_{x}$until a later time, i.e.$E_{x}$leads$E_{y}$.

Phase retarders	Corresponding Jones matrix
Quarter-wave platewith fast axis vertical	${\rm {e}}^{\frac {i\pi }{4}}{\begin{pmatrix}1&0\\0&-i\end{pmatrix}}$
Quarter-wave platewith fast axis horizontal	${\rm {e}}^{-{\frac {i\pi }{4}}}{\begin{pmatrix}1&0\\0&i\end{pmatrix}}$
Quarter-wave platewith fast axis at angle$\theta$w.r.t the horizontal axis	${\rm {e}}^{-{\frac {i\pi }{4}}}{\begin{pmatrix}\cos ^{2}\theta +i\sin ^{2}\theta &(1-i)\sin \theta \cos \theta \\(1-i)\sin \theta \cos \theta &\sin ^{2}\theta +i\cos ^{2}\theta \end{pmatrix}}$
Half-wave plate rotated by$\theta$	${\begin{pmatrix}\cos 2\theta &\sin 2\theta \\\sin 2\theta &-\cos 2\theta \end{pmatrix}}$
Half-wave platewith fast axis at angle$\theta$w.r.t the horizontal axis	${\rm {e}}^{-{\frac {i\pi }{2}}}{\begin{pmatrix}\cos ^{2}\theta -\sin ^{2}\theta &2\cos \theta \sin \theta \\2\cos \theta \sin \theta &\sin ^{2}\theta -\cos ^{2}\theta \end{pmatrix}}$
General Waveplate (Linear Phase Retarder)	${\rm {e}}^{-{\frac {i\eta }{2}}}{\begin{pmatrix}\cos ^{2}\theta +{\rm {e}}^{i\eta }\sin ^{2}\theta &\left(1-{\rm {e}}^{i\eta }\right)\cos \theta \sin \theta \\\left(1-{\rm {e}}^{i\eta }\right)\cos \theta \sin \theta &\sin ^{2}\theta +{\rm {e}}^{i\eta }\cos ^{2}\theta \end{pmatrix}}$
Arbitrary birefringent material (Elliptical phase retarder)	${\rm {e}}^{-{\frac {i\eta }{2}}}{\begin{pmatrix}\cos ^{2}\theta +{\rm {e}}^{i\eta }\sin ^{2}\theta &\left(1-{\rm {e}}^{i\eta }\right){\rm {e}}^{-i\phi }\cos \theta \sin \theta \\\left(1-{\rm {e}}^{i\eta }\right){\rm {e}}^{i\phi }\cos \theta \sin \theta &\sin ^{2}\theta +{\rm {e}}^{i\eta }\cos ^{2}\theta \end{pmatrix}}$

The Jones matrix for an arbitrary birefringent material is the most general form of a polarization transformation in the Jones calculus; it can represent any polarization transformation. To see this, one can show

${\begin{aligned}&{\rm {e}}^{-{\frac {i\eta }{2}}}{\begin{pmatrix}\cos ^{2}\theta +{\rm {e}}^{i\eta }\sin ^{2}\theta &\left(1-{\rm {e}}^{i\eta }\right){\rm {e}}^{-i\phi }\cos \theta \sin \theta \\\left(1-{\rm {e}}^{i\eta }\right){\rm {e}}^{i\phi }\cos \theta \sin \theta &\sin ^{2}\theta +{\rm {e}}^{i\eta }\cos ^{2}\theta \end{pmatrix}}\\&={\begin{pmatrix}\cos(\eta /2)-i\sin(\eta /2)\cos(2\theta )&-\sin(\eta /2)\sin(\phi )\sin(2\theta )-i\sin(\eta /2)\cos(\phi )\sin(2\theta )\\\sin(\eta /2)\sin(\phi )\sin(2\theta )-i\sin(\eta /2)\cos(\phi )\sin(2\theta )&\cos(\eta /2)+i\sin(\eta /2)\cos(2\theta )\end{pmatrix}}\end{aligned}}$

The above matrix is a general parametrization for the elements ofSU(2),using the convention

$\operatorname {SU} (2)=\left\{{\begin{pmatrix}\ Alpha &-{\overline {\beta }}\\\beta &{\overline {\ Alpha }}\end{pmatrix}}:\ \ \ Alpha,\beta \in \mathbb {C},\ \ |\ Alpha |^{2}+|\beta |^{2}=1\right\}~$

where the overline denotescomplex conjugation.

Finally, recognizing that the set ofunitary transformationson$\mathbb {C} ^{2}$can be expressed as

$\left\{{\rm {e}}^{i\gamma }{\begin{pmatrix}\ Alpha &-{\overline {\beta }}\\\beta &{\overline {\ Alpha }}\end{pmatrix}}:\ \ \ Alpha,\beta \in \mathbb {C},\ \ |\ Alpha |^{2}+|\beta |^{2}=1,\ \ \gamma \in [0,2\pi ]\right\}$

it becomes clear that the Jones matrix for an arbitrary birefringent material represents any unitary transformation, up to a phase factor${\rm {e}}^{i\gamma }$.Therefore, for appropriate choice of$\eta$,$\theta$,and$\phi$,a transformation between any two Jones vectors can be found, up to a phase factor${\rm {e}}^{i\gamma }$.However, in the Jones calculus, such phase factors do not change the represented polarization of a Jones vector, so are either considered arbitrary or imposed ad hoc to conform to a set convention.

The special expressions for the phase retarders can be obtained by taking suitable parameter values in the general expression for a birefringent material.In the general expression:

• The relative phase retardation induced between the fast axis and the slow axis is given by$\eta =\phi _{y}-\phi _{x}$
• $\theta$is the orientation of the fast axis with respect to the x-axis.
• $\phi$is the circularity.

Note that for linear retarders,$\phi$= 0 and for circular retarders,$\phi$= ±$\pi$/2,$\theta$=$\pi$/4. In general for elliptical retarders,$\phi$takes on values between -$\pi$/2 and$\pi$/2.

Axially rotated elements

Assume an optical element has its optic axisperpendicular to the surface vector for theplane of incidenceand is rotated about this surface vector by angleθ/2(i.e., theprincipal planethrough which the optic axis passes,makes angleθ/2with respect to the plane of polarization of the electric fieldof the incident TE wave). Recall that a half-wave plate rotates polarization astwicethe angle between incident polarization and optic axis (principal plane). Therefore, the Jones matrix for the rotated polarization state, M(θ), is

$M(\theta )=R(-\theta )\,M\,R(\theta ),$

where$R(\theta )={\begin{pmatrix}\cos \theta &\sin \theta \\-\sin \theta &\cos \theta \end{pmatrix}}.$

This agrees with the expression for a half-wave plate in the table above. These rotations are identical to beam unitary splitter transformation in optical physics given by

$R(\theta )={\begin{pmatrix}r&t'\\t&r'\end{pmatrix}}$

where the primed and unprimed coefficients represent beams incident from opposite sides of the beam splitter. The reflected and transmitted components acquire a phaseθ_randθ_t,respectively. The requirements for a valid representation of the element are

$\theta _{\text{t}}-\theta _{\text{r}}+\theta _{\text{t'}}-\theta _{\text{r'}}=\pm \pi$

and $r^{*}t'+t^{*}r'=0.$

Both of these representations are unitary matrices fitting these requirements; and as such, are both valid.

Arbitrarily rotated elements

This would involve a three-dimensionalrotation matrix.See Russell A. Chipman and Garam Yun for work done on this.

See also

• Polarization
• Scattering parameters
• Stokes parameters
• Mueller calculus
• Photon polarization

Further reading

• E. Collett,Field Guide to Polarization,SPIE Field Guides vol.FG05,SPIE (2005).ISBN0-8194-5868-6.
• D. Goldstein and E. Collett,Polarized Light,2nd ed., CRC Press (2003).ISBN0-8247-4053-X.
• E. Hecht,Optics,2nd ed., Addison-Wesley (1987).ISBN0-201-11609-X.
• Frank L. Pedrotti, S.J. Leno S. Pedrotti,Introduction to Optics,2nd ed., Prentice Hall (1993).ISBN0-13-501545-6
• A. Gerald and J.M. Burch,Introduction to Matrix Methods in Optics,1st ed., John Wiley & Sons(1975).ISBN0-471-29685-6
• Jones, R. Clark (1941). "A new calculus for the treatment of optical systems, I. Description and Discussion of the Calculus".Journal of the Optical Society of America.31(7): 488–493.doi:10.1364/JOSA.31.000488.
• Hurwitz, Henry; Jones, R. Clark (1941). "A new calculus for the treatment of optical systems, II. Proof of three general equivalence theorems".Journal of the Optical Society of America.31(7): 493–499.doi:10.1364/JOSA.31.000493.
• Jones, R. Clark (1941). "A new calculus for the treatment of optical systems, III The Sohncke Theory of optical activity".Journal of the Optical Society of America.31(7): 500–503.doi:10.1364/JOSA.31.000500.
• Jones, R. Clark (1942). "A new calculus for the treatment of optical systems, IV".Journal of the Optical Society of America.32(8): 486–493.doi:10.1364/JOSA.32.000486.
• Fymat, A. L. (1971). "Jones's Matrix Representation of Optical Instruments. I: Beam Splitters".Applied Optics.10(11): 2499–2505.Bibcode:1971ApOpt..10.2499F.doi:10.1364/AO.10.002499.PMID20111363.
• Fymat, A. L. (1971). "Jones's Matrix Representation of Optical Instruments. 2: Fourier Interferometers (Spectrometers and Spectropolarimeters)".Applied Optics.10(12): 2711–2716.Bibcode:1971ApOpt..10.2711F.doi:10.1364/AO.10.002711.PMID20111418.
• Fymat, A. L. (1972). "Polarization Effects in Fourier Spectroscopy. I: Coherency Matrix Representation".Applied Optics.11(1): 160–173.Bibcode:1972ApOpt..11..160F.doi:10.1364/AO.11.000160.PMID20111472.
• Gill, Jose Jorge; Bernabeu, Eusebio (1987). "Obtainment of the polarizing and retardation parameters of a non-depolarizing optical system from the polar decomposition of its Mueller matrix".Optik.76:67–71.
• Brosseau, Christian; Givens, Clark R.; Kostinski, Alexander B. (1993). "Generalized trace condition on the Mueller-Jones polarization matrix".Journal of the Optical Society of America A.10(10): 2248–2251.Bibcode:1993JOSAA..10.2248B.doi:10.1364/JOSAA.10.002248.
• McGuire, James P.; Chipman, Russel A. (1994). "Polarization aberrations. 1. Rotationally symmetric optical systems".Applied Optics.33(22): 5080–5100.Bibcode:1994ApOpt..33.5080M.doi:10.1364/AO.33.005080.PMID20935891.S2CID3805982.
• Pistoni, Natale C. (1995). "Simplified approach to the Jones calculus in retracing optical circuits".Applied Optics.34(34): 7870–7876.Bibcode:1995ApOpt..34.7870P.doi:10.1364/AO.34.007870.PMID21068881.
• Moreno, Ignacio;Yzuel, Maria J.;Campos, Juan; Vargas, Asticio (2004). "Jones matrix treatment for polarization Fourier optics".Journal of Modern Optics.51(14): 2031–2038.Bibcode:2004JMOp...51.2031M.doi:10.1080/09500340408232511.hdl:10533/175322.S2CID120169144.
• Moreno, Ivan (2004). "Jones matrix for image-rotation prisms".Applied Optics.43(17): 3373–3381.Bibcode:2004ApOpt..43.3373M.doi:10.1364/AO.43.003373.PMID15219016.S2CID24268298.
• William Shurcliff(1966)Polarized Light: Production and Use,chapter 8 Mueller Calculus and Jones Calculus, page 109,Harvard University Press.

External links

• Jones Calculus written by E. Collett on Optipedia