Optical Materials
  Optical Glass
  Low Expansion Materials
  IR Materials
Micro-Optical Components
Fiber Optic Components
Light Sources & Photodiodes


Sapphire has a unique combination of physical, chemical and optical properties, which make it resistant to high temperature, thermal shock, water and sand erosion, and scratching. It is a superior IR window material for use under such conditions as high temperature and pressure, thermal shock, corrosion resistance, abrasion resistance or chemical attack. Sapphire exhibits high internal transmittance all the way from 150nm to 6um. It is very hard, second only to diamond. Large sizes are grown by using the heat exchanger method (HEM). Sapphire has a hexagonal crystalline structure and exhibits birefringence, a difference of 0.008 (refractive index of e-ray is smaller, negative uniaxial crystal). Besides optical applications, C-plane sapphire substrates are widely used to grow III-V and II-VI compounds such as GaN for blue LED and laser diodes, while R-plane sapphire substrates are used for the hetero-epitaxial deposition of silicon for microelectronic IC applications.


                      Figure 1: Refractive index verse wavelength for O-ray


     Figure 2: 1-mm thick sapphire external transmittance curve


                   Figure 3: Sapphire Unit Cell

  Coefficient of Linear Thermal Expansion
°C (/°C)
Parallel to C Axis 7.7X10-6
Perpendicular to C Axis 7.0X10-6
  Thermal Conductivity (40°C  W/m·K) 25.12
  Melting Point (°C) 2053
  Specific Heat (J/(Kg·K) 0.75X103
  Density (g/cm3) 3.99  
  Young's Modulus (GPa) 345
  Poisson's Ratio 0.18~0.29 (Orientation Dependent)
  Shear Modulus (GPa) 146
  Mohs Hardness 9
  Lattice Constants (Å) a=4.763   c=13.003  
  Dielectric Strength (V/m)
  Dielectric Constant
Parallel to C Axis 11.5 (1MHz)
Perpendicular to C Axis 9.3 (1MHz)
  Volume Resistance (Ω·cm, 20°C) >1014  
  Table 1:Sapphire Thermal and Mechanical Properties
IR Materials :  

Copyright © 2016 Precision Micro-Optics Inc. All Rights Reserved.