Achromatic wave plate is a special kind of Zero Order wave plate, comprised of two wave plates made by two different birefringent materials (e.g. crystal quartz and magnesium fluoride). The existence of chromatic dispersion greatly affects the refractive indices of materials. The two birefringent materials which construct the achromatic wave plates have complementary birefringent properties that could attenuate the chromatic dispersion effects so that excessive shifts of retardation over wavelength change in the first wave plate could be counterbalanced by the second wave plate. This results in a virtually flat response of phase delay over a broad wavelength band (usually hundreds of nanometers), therefore achromatic wave plate is an excellent choice for applications orienting tunable laser sources, femtosecond laser systems, spectroscopy, and other systems concerning broadband light sources.

The two most common phase retardation values are lambda/2 and lambda/4 retardation, half wave plates could be applied to the rotation of vertical polarization and horizontal polarization, whilst quarter wave plates could be used for conversion of linear and circular polarization. Crysmit offers Achromatic Half Wave plates and Achromatic Quarter Wave plates made from single crystal quartz and magnesium fluoride (MgF2), configured with a high-quality AR coating. The two wave plates are either cemented using NOA61 or with an architecture of an air gap in between. Achromatic wave plates with an air-spaced design are coated on all faces, then mounted on opposite sides of a spacer, placed within a cell, to form an air gap between the quartz wave plate and the MgF2 wave plate. The air-spaced modules have particularly promoted damage threshold greater than 500MW/cm^2, and are adaptive to high power lasers.

Off-the-shelf achromatic wave plates are available for online shopping in Crysmit. The standard achromatic wave plates are of half or quarter retardation, with three optional wavelength ranges: 450-650nm, 700-1000nm, 950-1300nm covering the visible, and a portion of the infrared Spectral. Fast despatch and economized pricing is guaranteed. Incidentally, If you have any other specific requirements, Crysmit also provides custom services where all the parameters could be tailored to suit your demand. 

Fig.1: Retardation curve of achromatic quarter wave plate at 450-680 nm           Fig.2: Retardation curve of achromatic half wave plate at 450-680 nm

Fig.4: Retardation curve of achromatic quarter wave plate at 700-1000 nm           Fig.5: Retardation curve of achromatic half wave plate at 700-1000 nm

Fig.5: Retardation curve of achromatic quarter wave plate at 950-1300 nm           Fig.6: Retardation curve of achromatic half wave plate at 950-1300 nm

What is an achromatic wave plate ?

An achromatic wave plate is a type of wave plate that is designed to have a consistent phase retardation across a broad range of wavelengths, thereby minimizing the effects of wavelength-dependent phase shifting. Unlike regular wave plates, which exhibit different phase retardation values at different wavelengths, achromatic wave plates are specifically engineered to provide nearly constant phase retardation over a wide spectral range.

What is the application field of achromatic wave plate ?

• Imaging Systems: Achromatic wave plates are used in imaging systems to correct for polarization aberrations that can occur due to the wavelength-dependent behavior of optical components. They ensure consistent and accurate imaging across different wavelengths, improving the overall image quality.
  

• Biomedical Optics: In biomedical optics, achromatic wave plates are employed in techniques such as polarization-sensitive optical coherence tomography (PS-OCT) and polarization microscopy. They help in characterizing and visualizing biological tissues by providing accurate polarization control and reducing artifacts caused by wavelength-dependent effects.

• Laser Diode Systems: Achromatic wave plates are used in laser diode systems to control and adjust the polarization state of laser beams. They ensure stable and consistent output polarization, which is essential in applications such as laser diode spectroscopy, fiber optic communications, and laser-based manufacturing processes.

• Ellipsometry: Achromatic wave plates are utilized in ellipsometry, a technique used to measure and analyze the optical properties of materials. They help in accurately determining the phase difference between the polarized components of reflected or transmitted light over a wide range of wavelengths, enabling precise characterization of thin films and surfaces.

• Optical Instrumentation: Achromatic wave plates are widely used in various optical instruments, including polarimeters, optical modulators, wave plate-based retardation plates, and wave plate-based tunable filters. They ensure wavelength-independent performance and allow for accurate measurement, modulation, and control of light polarization.

• Astronomical Optics: Achromatic wave plates find applications in astronomical optics, particularly in instruments used for polarimetry and spectroscopy. They help in studying the polarization properties of celestial objects and analyzing the spectral signatures of astronomical phenomena across a broad range of wavelengths.

Literature

• Terahertz achromatic quarter-wave plate;JB Masson, G Gallot - Optics letters, 2006 - opg.optica.org

• Achromatic quarter-wave plates using the dispersion of form birefringence; Hisao Kikuta, Yasushi Ohira, and Koichi Iwata

• Achromatic combinations of birefringent plates; Part II. An achromatic quarter-wave plate; S. Pancharatnam

• Solution-processed inorganic perovskite crystals as achromatic quarter-wave plates

• Achromatic and super-achromatic zero-order wave plates;AV Samoylov, VS Samoylov, AP Vidmachenko… - Journal of Quantitative …, 2004 - Elsevier

• Biologically inspired achromatic wave plates for visible light;YJ Jen, A Lakhtakia, CW Yu, CF Lin, MJ Lin… - Nature …, 2011 - nature.com

• Achromatic linear retarders;JM Beckers - Applied Optics, 1971 - opg.optica.org

• Achromatic quarter-wave plate using crystalline quartz; Appl. Opt.(2012)