Polymer Optical Materials
Refractive index, group index and Abbe number of PMMA, polycarbonate, polystyrene, Zeonex, NOA 61 and SU-8 from published dispersion fits, with surface reflectance and the NA of a polymer core/cladding pair.
Refractive index n at 633.0 nm
1.49081
fit range 420–1620 nm
Group index n_g
1.51220
dn/dλ = -0.03378 µm⁻¹
Abbe number V_d
59.4
(n_d − 1)/(n_F − n_C) from the fit
Reflectance per surface
3.883 %
normal incidence, in air
Numerical aperture
—
choose a cladding
Acceptance half-angle
—
arcsin(NA), launch from air
Refractive index over each fit's range
- PMMA (acrylic)
- Polycarbonate (PC)
- Polystyrene (PS)
- Cyclo-olefin polymer (Zeonex E48R)
- Norland NOA 61 (cured adhesive)
- SU-8 2000 (uncured resist)
Polymers
| Polymer | n_d | V_d | Range | Source |
|---|---|---|---|---|
| PMMA (acrylic) | 1.4925 | 59.4 | 420–1620 nm | G. Beadie et al., Appl. Opt. 54, F139 (2015) |
| Polycarbonate (PC) | 1.5848 | 27.9 | 437–1052 nm | N. Sultanova et al., Acta Phys. Pol. A 116, 585 (2009), 20 °C; Sellmeier fit by M. Polyanskiy |
| Polystyrene (PS) | 1.5916 | 29.5 | 437–1052 nm | N. Sultanova et al., Acta Phys. Pol. A 116, 585 (2009), 20 °C; Sellmeier fit by M. Polyanskiy |
| Cyclo-olefin polymer (Zeonex E48R) | 1.5305 | 51.8 | 437–1052 nm | N. Sultanova et al., Acta Phys. Pol. A 116, 585 (2009), 20 °C |
| Norland NOA 61 (cured adhesive) | 1.5597 | 42.4 | 450–1550 nm | Norland Products, NOA 61 data sheet (Cauchy fit as recorded by refractiveindex.info, 2016; within 5e-4 of the sheet's 480–644 nm table) |
| SU-8 2000 (uncured resist) | 1.5902 | 34.8 | 320–800 nm | MicroChem, SU-8 2000 data sheet (2011), Cauchy coefficients, uncured |
Model
Sellmeier n² = 1 + Bλ²/(λ² − C); PMMA n² = A + Σ Bᵢλ^pᵢ; Cauchy n = A + B/λ² + C/λ⁴
n_g = n − λ dn/dλ, R = ((n − 1)/(n + 1))², NA = √(n₁² − n₂²)
Each fit holds only inside its measured range. Indices vary by grade, cure and temperature: two PMMA samples differ by up to 0.003. With index accuracy ±0.001 and n_F − n_C ≈ 0.01, the Abbe numbers from these fits are good to about 10 %. Absorption and loss are not modelled; C–H vibrational overtones make these polymers lossy in the near infrared.
Model and references
Textbook approximation. A standard approximation from the literature (for example paraxial, plane-wave or Gaussian-beam), valid within the range the page states. About the tiers
Published fits (Sellmeier, n² power series, Cauchy), each valid only in its measured range; Sultanova's fits match her data within 0.001. Grade, cure and temperature shift n by ~0.003, so V_d is good to ~10 %. No loss model: C–H overtones make these polymers lossy in the near infrared.
- Sultanova N., Kasarova S., Nikolov I. (2009). Dispersion properties of optical polymers. Acta Phys. Pol. A 116, 585–587. Table: measured indices (±0.001, 20 °C) and Abbe numbers of PMMA, PC, PS and Zeonex E48R. doi:10.12693/APhysPolA.116.585
- Beadie G., Brindza M., Flynn R. A., Rosenberg A., Shirk J. S. (2015). Refractive index measurements of poly(methyl methacrylate) (PMMA) from 0.4–1.6 μm. Appl. Opt. 54, F139–F143. doi:10.1364/AO.54.00F139
- Polyanskiy M. N. refractiveindex.info database: Sellmeier fits of Sultanova's data; Norland NOA 61 and MicroChem SU-8 2000 (uncured) Cauchy coefficients. refractiveindex.info
- Norland Products. NOA 61 technical data sheet: cured-polymer index 1.56 and 1.5562, 1.5594, 1.5634, 1.5691, 1.5754 at 643.8, 589.6, 546.1, 480.0, 435.8 nm. web.archive.org