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Laser Crystals and Components

Waveplates and Retarders

Waveplates or Phase Retardation Plates, Retarders are polarizing optics used to manipulate the polarization state of the transmitting light without attenuating, deviating, or displacing the light. The working principle of a waveplate, or a retardation plate, is to utilize the birefringence of certain materials which separates the incident light beam into two components along two orthogonal optical axes within the birefringent material. The phase retardation between the two components of the incident light contributes to changes in the polarization state. (There are also the Fresnel Rhomb Retarders which work through a different principle, that is, the Total Internal Reflection.) It is possible to control the phase shift between the two polarization components of a light wave, by adjusting the thickness of the waveplates. Some external factors, such as the variation of wavelength, ambient temperature, and the angle of the incident might all have impacts on the retardation of waveplates and retarders.

The most common waveplates are half waveplates and quarter waveplates. A half waveplate, sometimes equivalently called half wave retarder or half-wavelength plate, induces a retardation of 1/2 lambada between the fast component and the slow component, resulting in a rotation of the polarization direction of the emerging light. Changing the angle between the original plane of polarization and the axes of the half waveplate, the angle rotated could be governed. Half wavelength plates are often applied for transforming vertical polarization into horizontal polarization and vice versa when orienting the incident linear polarization at 45 degrees to the optical axis. Quarter waveplates or quarter retardation plates, on the other hand, generate retardation of λ/4 between the fast and slow components, the ultimate effect is the conversion of linear polarization to circular polarization or vice versa.  Besides, Shalom EO also offers octadic waveplates and full waveplates.  Standard-mounted modules of waveplates are configured with Dia. 25.4mm, C.A. 18mm aluminum mounts, which are all engraved with fast axes on the outside in the form of a straight line. The unmounted versions also have their fast axes indicated.

Hangzhou Shalom EO offers a variety of wave plates and phase retardation plates, retarders in various forms including True Zero-Order, Zero-Order, Low-Order, Dual Wavelength Waveplates, Super Achromatic, Achromatic Waveplates, Fresnel Rhomb Retarders. In Shalom EO, feel free to pick the retardation and wavelength of your interest, where a vast variety of half-wave, quarter-wave, or other wavelengths of retardation for single wavelength, dual/triple wavelength options, or broadband/achromatic wavelength ranges are available, with the applicable spectral ranges from UV to Infrared wavelength ranges. These waveplates and retarders are made from a manifold of materials including Quartz, Magnesium Fluoride (MgF2), UV Fused silica,  with single-plate, double-plate, sixfold-plate, or substrates-combined structures. The assembled waveplates are either aligned using cementing, optically contacting,  or with an air-spaced design. Both off-the-shelf and customized modules are available.

If you want a more thorough understanding of waveplates and retarders, Check out our article about Introduction to Waveplates and Retarders in the resource sector.

Below is some brief guidance to help you understand different kinds of waveplates and retarders, so that you may form a concept before ordering:

Shalom EO's Zero Order Waveplates are comprised of two multiple-order plates, with their axes crossed so that the effective retardation is the difference between them. They have comparatively superior retardation stability to wavelength shifts and temperature changes than low-order waveplates. And there are three ways to construct the two constituent plates, Air Spaced Zero Order Waveplates, Optically Contacted Zero Order Waveplates and NOA61 Cemented Zero Order Waveplates. The air-spaced and optically contacted designs are more recommendable for high-power applications, where the optically contacted modules feature particularly fine wavefront distortion and parallelism. 

Shalom EO's Dual Wavelength Zero Order WaveplatesDual Wavelength Waveplates provide retardation at two individual wavelengths in applications for dual-wavelength light sources according to the fitting of the refractive index at different wavelengths. Dual Wavelength Waveplates are particularly useful when used in conjunction with other polarization-sensitive components to separate coaxial laser beams of different wavelengths or elevate and promote the conversion efficiency of Solid State SHG Lasers. Hangzhou Shalom EO offers Multiple wavelength waveplates (majorly Dual Wavelength Waveplates, also including Triple Wavelength Waveplates of high damage threshold.

Shalom EO's True Zero Order Waveplates are made from one ultra-thin waveplate. True zero-order waveplates excel zero-order waveplates in all aspects and are recommended for more precise operations or applications within a broadened wavelength. Besides the free-standing single plate version, Shalom EO offers true zero-order waveplates with BK7 substrate and aluminum mounts for easy handling. Two types of materials are optional: Quartz for routine wavelengths, and MgF2 for >3000nm applications.

Shalom EO's Achromatic Waveplates are constructed from two waveplates of different materials (quartz and magnesium fluoride) to achieve nearly constant retardation across a broad spectral band. The stocked versions include achromatic half wave plates and achromatic quarter wave plates.

Shalom EO's Super Achromatic Waveplates are an improved version of the achromatic waveplates comprised of six waveplates (three quartz waveplates and three MgF2 waveplates), which minimize the chromatic dispersion and enable more constant retardation through a broad wavelength range. 

Shalom EO's Fresnel Rhomb Retarders have the same basic function as waveplates, the distinction is that Fresnel Rhombs achieve the retardation of interest by utilizing total internal reflection. This allows almost flat responsiveness in retardation across an even broader wavelength range than the achromatic waveplates. 

Shalom EO's Low-order Waveplates are multiple-order waveplates with a relatively low order number. Low-order waveplates are less expensive, but just like multiple-order waveplates, are susceptible to external factors (such as temperature) compared to zero-order counterparts, thereby being suitable for operations in a controlled environment.