Lateral Displacement Polarizing Beamsplitter

Main Features

• High polarization purity: The polarization extinction ratio is up to >1000:1, ensuring efficient separation of s-light and p-light.
• Lateral displacement structure: Outputs two beams of parallel polarized light, and the displacement can be flexibly customized in the range of 0.5–2 mm.
• High transmittance and high reflectivity: A multi-layer dielectric film system is employed, achieving transmittance greater than 95% and reflectivity exceeding 99%.

• Excellent optical flatness: Surface flatness up to λ/8 at 632.8 nm ensures minimal wavefront distortion.
• High laser resistance: Damage threshold greater than 10 J/cm² at 1064 nm, suitable for use in medium- to high-power laser systems.
• Strong environmental stability: Operating temperature range from -40°C to +200°C, making it suitable for complex industrial environments.

Working Principle and Structure

Lateral displacement polarizing beamsplitters are typically made from highly birefringent crystals such as calcite or YVO₄. When unpolarized light enters the crystal, it is separated into two beams with orthogonal polarizations:

• Ordinary light (O-light)and extraordinary light (E-light) are separated in parallel directions due to the difference in refractive index, resulting in lateral displacement.
• By controlling the crystal thickness and angle of incidence, different displacements and polarization separation accuracy can be achieved.

Advantages of this design include compact structure, consistent optical path, and no introduction of angular deviations, making it ideal for systems with high requirements for precision interference and optical path parallelism.

Materials & Manufacturing

Lateral displacement polarizing beamsplitter uses highly birefringent crystal materials such as calcite, YVO₄, or BBO, offering excellent optical anisotropy and thermal stability. Optical surface prepared through high-precision polishing with surface quality up to 20-10 Scratch-Dig standard to ensure interference-level flatness.

Coating: Ion beam sputtering (IBS) multi-layer dielectric film system, low absorption and low scattering, with anti-reflective coating R < 0.5% in the working band. Overall structure controlled with tight thickness tolerances (±0.02 mm) and optical axis consistency to ensure stable performance in high-precision optical systems.

Core Optical Properties

• Precisely controlled lateral displacement ensures a dual-beam parallel output.
• The design with extremely low insertion loss enhances system signal stability.
• The high extinction ratio structure provides excellent polarization separation performance.
• Stable optical axis alignment reduces thermal drift and mechanical errors.

Typical Applications

• Laser interferometer and wavefront detection systems
• Optical communication polarization beam splitting and multiplexing modules
• Polarization imaging and microscopy systems
• Optical test instruments and precision measurement systems
• Laser polarization control and power monitoring units

Design Considerations

• Displacement distance: 2–5 mm (customizable according to the system’s optical path spacing).
• Polarization Purity: High extinction ratio, ideal for scientific measurement applications.
• Optical Coating: Select a specific wavelength anti-reflective (AR) coating to minimize reflection loss.
• Working Environment: An encapsulated installation is recommended to minimize temperature drift and the effects of humidity.
• Mechanical Fit: Ensure the flatness of the mounting surface and the concentricity of the optical axis to prevent offset errors.