Silicon (Si)
Silicon (Si) is a versatile material widely used in optics, particularly in the infrared (IR) region. It is highly transparent to IR light making it ideal for lenses, windows, and filters in IR imaging systems and spectroscopy. Silicon also has a high refractive index (around 3.4), allowing for effective light manipulation in optical devices. Additionally, its excellent thermal conductivity and stability make it suitable for high-power laser applications and harsh environments. Silicon’s compatibility with semiconductor manufacturing processes further enables the integration of optical components with electronic systems, enhancing the development of advanced photonic devices.
Optical Properties
Refractive Index: 3.42
Thermal Co-efficient of Refractive Index: 1.5 x 10-6
Transmission Range: 1.2 – 9.0 µm
Thermal Properties
Thermal Linear Expansion: 2.6 x 10-6 /°C at 20°C
Thermal Conductivity: 163.3 W m⁻¹ K⁻¹ at 273 K
Specific Heat Capacity: 703 J Kg⁻¹ K⁻¹
Melting Point: 1420 °C
Mechanical Properties
Density: 2.33 g/cc
Knoop Hardness: 1150
Young Modulus: 131 GPa
Shear Modulus: 79.9 GPa
Poisson Ratio: 0.266
| Wavelength (µm) | Refractive Index (n) |
| 1.357 | 3.4975 |
| 1.367 | 3.4962 |
| 1.395 | 3.4929 |
| 1.529 | 3.4795 |
| 1.660 | 3.4696 |
| 1.709 | 3.4664 |
| 1.813 | 3.4608 |
| 1.970 | 3.4537 |
| 2.153 | 3.4476 |
| 2.325 | 3.4430 |
| 2.714 | 3.4358 |
| 3.000 | 3.4320 |
| 3.303 | 3.4300 |
| 3.500 | 3.4284 |
| 4.000 | 3.4257 |
| 4.258 | 3.4245 |
| 4.500 | 3.4236 |
| 5.000 | 3.4223 |
| 5.500 | 3.4213 |
| 6.000 | 3.4202 |
| 6.500 | 3.4195 |
| 7.000 | 3.4189 |
| 7.500 | 3.4186 |
| 8.000 | 3.4184 |
| 8.500 | 3.4182 |
| 10.00 | 3.4179 |
| 10.50 | 3.4178 |
| 11.04 | 3.4176 |
