28 +44 (0) 1904 788600 | Edmund Optics®
Material Transmission
Range
Index of
Refraction
(n)
Abbe
Number
(v)
Group
Velocity
Dispersion
(fs2/mm)
dn/dT
(10-6/
K)
Coefficient
of Thermal
Expansion
(10-6/K)
Relative
Price
CaF2
10 200 nm - 7 μm 1,429 95,1 17,280 -10,6 8,85 €€€
UV Grade Fused
Silica(Corning
HPFS® 7980)11
185 nm - 2,1 μm 1,450 67,8 16,476 9,6 0,55 €€
KrF Grade Fused
Silica (Corning
HPFS® 7980)11
185 nm - 2,1 μm,
T ≥ 99,9% @
248 nm
1,450 67,8 16,476 9,6 0,55 €€
IR Grade Fused
Silica (Corning
HPFS® 7979)11
300 nm - 3,5 μm 1,451 67,8 16,476 9,7 0,55 €€
N-BK712 350 - 2000 nm 1,507 64,2 22,369 3,0 7,1 €
N-SF512 330 - 2500 nm 1,651 32,3 77,779 3,4 7,9 €
Sapphire*13 200 - 5500 nm 1,755 72,2 28,588 13,1 5,4 €€€
N-SF1112 400 - 2500 nm 1,754 25,8 118,44 2,4 8,5 €
Un-doped YAG14 210 nm- 5 μm 1,815 52,6 62,660 9,1 7,8 €€
*Sapphire is a birefringent material and all specifications correspond parallel to C-Axis
Table 8.4: Common laser optics substrates and their key properties organized
by ascending refractive index (all values at 1064 nm and 20° C)
nD, nF and nC are the substrate’s refractive indices at the wavelengths of
the Fraunhofer D- (589.3 nm), F- (486,1 nm) and C- (656,3 nm) spectral
lines. The Abbe number of a material may also be described at
any wavelength using the derivative of refractive index with respect to
wavelength:
8.8
Intermodal dispersion is a dependence of the group velocity of light in a
waveguide, such as a multimode fiber, on the optical frequency and the
propagation mode,2 In multimode optical fiber communication systems,
this severely limits the achievable data transmission rate, or bit rate. Intermodal
dispersion could be prevented by using single-mode fibers or
multimode fibers with a parabolic refractive index profile.
Polarization mode dispersion is the dependence of light's propagation
characteristics in a medium on polarization state, which can be relevant
in high data rate single-mode fiber systems. All three types of dispersion
may cause temporal broadening or compression of ultrashort pulses in
free space or optical fibers, potentially causing separate pulses to blend
together and become unrecognizable (Figure 8.8).
Section 8.9: Common Materials
Understanding the most commonly used laser optics materials will allow
for easy navigation of EO’s wide selection of laser optics components.
Table 8.4 below lists common substrates used for laser optics,
along with their key properties, followed by transmission curves for
each material (Figure 8.9). All values in Table 8.4 are at 1064 nm and
20° C and all transmission curves show the internal transmission of 5
mm thick substrates without Fresnel reflections. Transmission data was
gathered using Edmund Optics’ spectrophotometers.
References
1. Paschotta, Rüdiger. Encyclopedia of Laser Physics and Technology,
RP Photonics, October 2017, www.rp-photonics.com/encyclopedia.html.
2. Ghatak, Ajoy, and K. Thyagarajan. “Optical Waveguides and Fibers.”
University of Connecticut, 2000.
3. “TIE-19: Temperature Coefficient of the Refractive Index.” Schott,
July 2016.
4. “TIE-28: Bubbles and Inclusions in Optical Glass.” Schott, May 2016.
5. F. Reitmayer and E. Schuster, "Homogeneity of Optical Glasses,"
Appl. Opt. 11, 1107-1111 (1972)
6. “TIE-26: Homogeneity of Optical Glass.” Schott, February 2016.
7. Fine, Kevin R, et al. “OPTICS FABRICATION: Subsurface Damage Is
Measured Nondestructively.” Laser Focus World, June 2006.
8. Finch, G. Ingle. “The Beilby Layer on Non-Metals.” Nature, vol. 138,
no. 3502, 1936, pp. 1010–1010., doi:10,1038/1381010a0.
9. Collier, David, and Rod Schuster. “Superpolishing Deep-UV Optics.”
Photonics Spectra, February 2005.
10. I. H. Malitson. “A redetermination of some optical properties of calcium
fluoride,” Appl. Opt. 2, 1103-1107 (1963)
11. “Corning HPFS® 7979, 7980, 8655 Fused Silica.” Corning,
February 2014.
12. “Optical Glass Data Sheets.” Schott, February 2014.
13. I. H. Malitson. “Refraction and dispersion of synthetic sapphire,”
J. Opt. Soc. Am. 52, 1377-1379 (1962)
14. Palik, Edward D., and Gorachand Ghosh. Handbook of Optical
Constants of Solids. Academic Press, 1998.
Figure 8.8: Dispersion can cause laser pulses traveling down fibers to
spread until they become unrecognizable
R (%)
90
80
70
60
50
40
30
20
10
0
Internal Transmission (5mm Thick Sample)
CaF2
UV Fused Silica
IR Fused Silica
N-BK7
N-SF5
N-SF11
0 750 1500 2250 3000 3750 4500 5250 6000 6750 7500 8250 9000 (nm)
Figure 8.9: Internal transmission curves for common optical materials
with no Fresnel reflections