Waveplate

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Waveplate

Waveplates (retarders) are made from birefringent materials which introduce a phase difference between the fast and slow principal axis of the waveplate. The optical axis of waveplate is parallel to the face. Light incident normal to the surface will be split to components polarized parallel and perpendicular to the optical axis with different refractive index and velocity in this device. The difference in velocities gives rise to a phase shift which is called retardance. At any specific wavelength the phase retardance is governed by the thickness of Waveplates. The standard waveplates we provided include half waveplates and quarter waveplates, other custom waveplates can also be provided upon request.

Half Waveplate

When applying a linearly polarized beam to a half waveplate, it emerges as a linearly polarized beam but its polarization plane is rotated with respect to the polarization plane of the input beam. The rotation of the polarization plane is such that the angle between the input polarization and the output polarization is twice the angle between the input polarization and the waveplate's axis. When applying a circularly polarized beam, a clockwise circular polarization will transform into a counter-clockwise circular polarization and vice versa. Half waveplates are often used as continuously adjustable polarization rotators and as a variable ratio beamsplitter when used in conjunction with a polarization beamsplitter cube.

Quarter Waveplate

When applying a linearly polarized beam with the polarization plane aligned at 45deg to the waveplate's principal plane, the output beam will be circularly polarized. Similarly when applying a circularly polarized beam to a ¦Ë/4 waveplate the output beam will be linearly 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 a certain angle. Quarter waveplates are widely used in creating circular polarization from linear or linear polarization from circular, ellipsometry, optical pumping, suppressing unwanted reflection, optical isolation and etc.

Types of Waveplate

Type		Feature
Zero Order	Cemented	Cemented by glue Better Temperature Bandwidth Wide Wavelength Bandwidth Moderate damage threshold
	Optical Contacted	No glue Better Temperature Bandwidth Wide Wavelength Bandwidth Better damage threshold
	Air Spaced	No glue, Mounted Better Temperature Bandwidth Wide Wavelength Bandwidth High damage threshold
True Zero Order	Cemented	Cemented by glue Better Temperature Bandwidth Wide Wavelength Bandwidth Moderate damage threshold
True Zero Order	Single Plate	Single plate Better Temperature Bandwidth Wide Wavelength Bandwidth High damage threshold Only 1310nm, 1550nm available
Multi Order		Low Temperature Bandwidth Low Wavelength Bandwidth High damage threshold Low cost
Dual Wavelength		Provide Specific Retardance At Two Different Wavelengths
Achromatic		Better Temperature Bandwidth Very broad Wavelength Bandwidth Cemented and air spaced available
Wedge Waveplate		Eliminate Etalon effect Eliminate Return Beam

How to choose a waveplate?

Firstly, you should know the retardation, is it a half waveplate or a quarter waveplate? Or even a special retardation? Then, you should know the size and working wavelength. This is important for waveplate. The retardation is different at different wavelength. It depends on wavelength. After confirm these conditions, we should choose a type of waveplate. If temperature bandwidth and wavelength bandwidth is important for you, you should choose zero order or true zero order. For zero order, optical contacted has better wavefront distortion and parallelism, air spaced has high damage threshold. True zero order is better than zero order waveplate at all parameters and can be used at more critical application. When temperature bandwidth and wavelength bandwidth is not a problem for you, multi order is a better choice, it is cheap. If a zero order or true zero order waveplate does not offer retardance over a wide enough wavelength band, one solution is to use an achromatic waveplate, it has over hundreds of nanometers bandwidth. For detailed information, please refer to above table or contact us.

Sometimes, the waveplate has unwanted Etalon effect, in order to eliminate this effect, Union Optic offer Wedge Waveplate to solve this problem. For detailed information, please contact us.

Due to the rotation activity of natural quartz crystal, it also can be used as polarization rotators so that the plane of input linearly polarized beam will be rotated at special angle which is determined by the thickness of quartz crystal. Left-handed and right-handed rotators can be offered by Union Optic now.

Standard Wavelength

Union Optic provides standard wavelength(nm) of half and quarter waveplates listed as below:

532	633	780	800	850	1064	1310	1550
Other wavelengths and special retardation waveplates can be provided upon request.