Tech Team · Kintek Solution

CVD (Chemical Vapor Deposition) diamond exhibits exceptional optical properties, making it a highly desirable material for a wide range of applications, from industrial to scientific and defense-related fields. Its optical characteristics include excellent transmittance across a broad spectral range, from deep ultraviolet to microwave wavelengths. It also possesses a high refractive index, low absorption coefficient, and remarkable dielectric strength. These properties make CVD diamond ideal for use in laser optics, windows for high-power lasers, and other applications requiring durability and optical clarity. Below, the key optical properties of CVD diamond are explained in detail.

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Key Points Explained:

1. Wide Spectral Transmittance

   • CVD diamond has the widest spectral band of any known material, extending from deep ultraviolet (0.23 μm) to far infrared and into the millimeter-wave microwave band.
   • This broad transmittance range makes it suitable for applications requiring optical clarity across multiple wavelengths, such as laser optics and industrial windows.
   • For example, it is particularly useful as an exit window for CO₂ lasers, which are commonly used in automotive cutting applications.

2. High Refractive Index

   • The refractive index of CVD diamond is 2.376 at a wavelength of 10 μm.
   • A high refractive index contributes to the material's ability to bend light effectively, which is beneficial in optical systems where precise light manipulation is required.

3. Low Absorption Coefficient

   • The absorption coefficient of CVD diamond ranges from 0.03 to 0.05 cm⁻¹ at 20°C.
   • A low absorption coefficient indicates minimal light loss as it passes through the material, making it highly efficient for optical applications.
   • This property is particularly advantageous in high-power laser systems, where energy loss must be minimized.

4. Microwave Permittivity and Loss Tangent

   • CVD diamond has a microwave permittivity of 5.7 and a loss tangent angle of 2×10⁻⁵ at 145 GHz.
   • These properties make it an excellent material for microwave and radio-frequency applications, where low signal loss and high dielectric performance are critical.

5. Dielectric Strength

   • The dielectric strength of CVD diamond is 1×10⁷ V/cm, which is exceptionally high.
   • This property ensures that the material can withstand high electric fields without breaking down, making it suitable for use in high-voltage optical and electronic systems.

6. Brilliance and Sparkle

   • CVD diamonds exhibit intense brilliance and sparkle, similar to natural diamonds.
   • This optical property is due to their high refractive index and excellent light dispersion, making them visually indistinguishable from natural diamonds.

7. Durability and Hardness

   • With a hardness of 8,500 kgf/mm² and a Mohs scale rating of 10, CVD diamond is one of the hardest materials known.
   • This durability ensures that its optical properties remain stable even under extreme conditions, such as high temperatures or mechanical stress.

8. Applications in Laser Optics

   • CVD diamond is an ideal material for laser optics, particularly as an exit window for CO₂ lasers.
   • Its ability to withstand high power and maintain optical clarity makes it indispensable in industrial laser cutting and welding applications.

9. Potential for Silicon Inclusions

   • During the CVD process, silicon inclusions can sometimes be introduced into the diamond due to the etching of silica windows in the growth chamber.
   • While these inclusions may slightly affect optical properties, they are generally minimal and do not significantly impact the material's overall performance.

10. Comparison to Natural Diamonds

    • CVD diamonds share the same internal structure, chemical composition, and optical properties as natural diamonds.
    • This makes them a cost-effective and sustainable alternative for applications requiring the optical and mechanical properties of natural diamonds.

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In summary, the optical properties of CVD diamond make it a versatile and high-performance material for a wide range of applications. Its broad spectral transmittance, high refractive index, low absorption coefficient, and exceptional durability make it ideal for use in laser optics, microwave systems, and industrial windows. These properties, combined with its cost-effectiveness and sustainability, position CVD diamond as a leading material in both scientific and industrial fields.

Summary Table:

Property	Value/Range	Application
Spectral Transmittance	0.23 μm (UV) to microwave band	Laser optics, industrial windows
Refractive Index	2.376 at 10 μm	Optical systems requiring precise light manipulation
Absorption Coefficient	0.03–0.05 cm⁻¹ at 20°C	High-power laser systems
Microwave Permittivity	5.7 at 145 GHz	Microwave and RF applications
Dielectric Strength	1×10⁷ V/cm	High-voltage optical and electronic systems
Hardness	8,500 kgf/mm² (Mohs 10)	Durable applications under extreme conditions
Brilliance and Sparkle	Similar to natural diamonds	Visually indistinguishable from natural diamonds
Applications	CO₂ laser exit windows, industrial optics	Laser cutting, welding, and high-power optical systems

Interested in leveraging the optical properties of CVD diamond for your applications? Contact us today to learn more!