Waveplates Optical Waveplate Windows - China

Waveplates (retardation plates or phase shifters) are made from

materials which exhibit birefringence.

The velocities of the

extraordinary and ordinary rays through the birefringent material varies

inversely with their refractive indices.

This difference in velocities

gives rise to a phase difference when the two beams recombine.

In the

case of an incident linearly polarized beam this is given by α=2πd(ne-

no)/λ, where α is phase difference; d is thickness of

waveplate; ne, no are refrective indices of extraordinary and ordinary

rays respectively; λ is wavelength.

At any specific wavelength the

phase difference is governed by the thickness of the retarder.

λ/ 2 Waveplates

The thickness of a half waveplate is such that the phase difference is 1/2-wavelength (λ/2, true zero

order) or certain multiple of 1/2-wavelength ((2n+1)λ/2, multiple order).

A linearly polarized beam incident on a half waveplate emerges as a linearly polarized beam but rotated

such that its angle to the optical axis is twice that of the incident beam.

Therefore, half-waveplates can be

used as continuously adjustable polarization rotators.

Half-waveplates are used to rotate the plane of

polarization, electro-optic modulation and as a variable ratio beamsplitter when used in conjunction with

a polarization cube.

λ/ 4 Waveplates

The thickness of the quarter waveplate is such that the phase difference is 1/4-wavelength (λ/4, true zero

order) or certain multiple of 1/4-wavelength ((2n+1)λ/4, multiple order).

If the angle θ (between the electric field vector of the incident linearly polarized beam and the retarder

principal plane) of the quarter waveplate is 45 degree , the emergent beam is ircularly polarized.

When a

quarter waveplate is double passed, i.e. by mirror reflection, it acts as a half waveplate and rotates the

plane of polarization to certain angle.

Quarter waveplate are used in creating circular, ellipsometry, optical

pumping, suppressing unwanted reflcetion and optical isolation.

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• Posted By: paradise photonics,INC.

• Phone: 8659183852091

• Address: D/2F,NO.A6 Baihuazhou Road,Pushang Industry Park,C, Fuzhou , China

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