High-performance NIR/SWIR material for laser and infrared systems
Silicon (Si) is a widely used infrared optical material transmitting from 1.2 to 8 μm. It offers excellent thermal conductivity (130 W/m·K), low thermal expansion, and good mechanical strength. Commonly used for NIR imaging, SWIR optics, and as a substrate for IR coatings. It is opaque in the visible spectrum.
Optical-grade Silicon is a crystalline semiconductor material widely used for infrared optics in the 1.2–8 μm range. It combines good optical transmission with exceptional thermal properties, making it ideal for applications requiring thermal stability.
Silicon's high thermal conductivity (130 W/m·K) and relatively low thermal expansion make it superior to Germanium in thermally demanding environments. It is widely used in NIR imaging, SWIR systems, and as beam splitters in FTIR instruments.
Reference data — verify with PhotonEdge for project-specific specifications.
| Property | Value |
|---|---|
| Coefficient of Thermal Expansion (CTE) | 2.6 × 10⁻⁶ /K |
| Thermal Conductivity | 149 W/m·K |
| dn/dT (Thermo-optic Coefficient) | 164 × 10⁻⁶ /K at 1.3 μm |
| Maximum Operating Temperature | ~400°C (in optical applications) |
Silicon has very high thermal conductivity and low CTE, but a very large dn/dT in the IR. Thermal management is critical for stable optical performance.
Broadband AR for MWIR atmospheric window. R < 0.5% per surface.
Typical use: MWIR thermal imaging
AR for SWIR range. Essential due to ~30% uncoated reflection.
Typical use: SWIR imaging and sensing
50/50 or custom ratio for FTIR applications.
Typical use: FTIR spectrometers
Transmits 1.2–8 μm. Not suitable for visible or LWIR (>8 μm) applications.
Excellent thermal conductivity (130 W/m·K) dissipates heat quickly. Much better than Ge for high-power applications.
High index (~3.4) requires AR coatings for transmission efficiency.
Density of 2.33 g/cm³ makes Si significantly lighter than Ge (5.32 g/cm³) — important for aerospace.
Very hard and brittle, diamond machining required. Care needed to avoid chipping and cracking during fabrication.
Can achieve optical quality surfaces with diamond polishing. Single-point diamond turning is also effective.
Stable at room temperature. Oxidation occurs above 300°C, limiting high-temperature optical use.
Moderate cost, readily available from semiconductor industry supply chains. Good value for IR applications.
Si is lighter, better thermal conductivity, but narrower IR range (1.2–8 vs 2–14 μm)
Si is harder and more thermally stable, but ZnSe covers broader range including CO₂ laser
Si covers IR; Sapphire covers UV-VIS-NIR. Different application domains.
Silicon is used for infrared optics operating in the 1.2–8 μm range, including NIR imaging, SWIR sensors, FTIR beam splitters, and MWIR thermal systems.
No. Silicon is opaque to visible light (below 1.2 μm). It appears metallic gray and reflective.
Silicon covers MWIR (3–5 μm) while Germanium covers LWIR (8–14 μm). For CO₂ laser at 10.6 μm, Germanium is required. For MWIR, Silicon offers better thermal stability and lighter weight.
Yes. Silicon's high thermal conductivity (130 W/m·K) makes it excellent for high-power NIR laser applications. It dissipates heat much better than Germanium.
AR coatings are essential due to ~30% uncoated reflection. Use AR 3-5 μm for MWIR, or AR 1.2-3 μm for SWIR applications.
Describe your application and wavelength requirements. Our engineering team will recommend the optimal material grade and specifications.
Request a Quote