Refractive index database

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Optical constants of (C2H4)n (Polyethylene, PE, HDPE, LDPE)
David et al. 2022: LLDPE film; n,k 2.00–12.3 µm

Wavelength: µm

Complex refractive index (n+ik)[ i ]

n   k   LogX   LogY   eV

Derived optical constants


Spin-coated LLDPE. Measured using approximately 270 nm thick film (concentration 2%, dissolved in Toluene). Data at λ < 2 μm removed on author's request.


M. David, D. Disnan, A. Lardschneider, D. Wacht, H. Hoang, G. Ramer, H. Detz, B. Lendl, U. Schmid, G. Strasser, B. Hinkov. Structure and mid-infrared optical properties of spin-coated polyethylene films developed for integrated photonics applications, Opt. Mater. Express 12, 2168-2180 (2022)


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Polyethylene, (C2H4)n (PE, HDPE, LDPE)

Polyethylene (PE, HDPE, LDPE, (C2H4)n) is the most abundantly produced plastic globally, known for its versatile nature and wide array of applications. Chemically composed of repeating ethylene units, polyethylene exists in various densities and molecular weights that result in different material properties. High-density polyethylene (HDPE) is renowned for its rigidity, strength, and impermeability, making it a popular choice for items like bottles, pipes, and containers. On the other hand, low-density polyethylene (LDPE) offers more flexibility and is frequently used in packaging films, plastic bags, and other applications that demand malleability. Optically, polyethylene is generally translucent to opaque, depending on its density and thickness. Its refractive characteristics can be affected by the density, molecular alignment, and crystallinity of the material. In both its high and low-density forms, polyethylene is celebrated for its chemical resistance, low cost, and easy processing, factors that collectively contribute to its ubiquity in the modern world.

Other names

  • polyethene
  • poly(methylene)


  • High-density polyethylene (HDPE)
  • Medium-density polyethylene (MDPE)
  • Low-density polyethylene (LDPE)
  • Linear low-density polyethylene (LLDPE)
  • Cross-linked polyethylene (XLPE/PEX)
  • Ultra-high-molecular-weight polyethylene (UHMWPE)

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