Optical Filters

Dielectric Mirror

Product introductionThe reflection of light incident on the metal coat layer or dielectric coat layer on the glass surface is called the front surface mirror. We can supply enhanced aluminum plus diel

Dielectric mirror, also known as Bragg mirror or distributed Bragg reflector (DBR), is a type of optical coating designed to reflect a wide range of wavelengths with exceptionally high reflectivity, typically exceeding 99%. Unlike conventional metallic mirrors that rely on the surface's conductivity to reflect light, dielectric mirrors utilize multiple layers of alternating high and low refractive index materials, all of which are transparent dielectrics.

Key Features of Dielectric Mirrors:
1.High Reflectivity:
 Dielectric mirrors can achieve near-total reflection across a broad or narrow band of wavelengths, depending on their design.
2.Wavelength Selectivity:
 By carefully choosing the layer materials, thicknesses, and the number of layers, the mirror can be tailored to reflect a specific range of wavelengths while transmitting others, making them useful for wavelength division multiplexing in optical communications.
3.Broadband or Narrowband Reflection:
 They can be designed for broadband reflection, covering a large portion of the spectrum, or for narrowband reflection, focusing on reflecting a very specific wavelength or a small band of wavelengths.
4.Low Loss and Absorption:
 Since they use dielectric materials that do not conduct electricity, there is minimal absorption of light, leading to low loss and high efficiency.
5.Angle-Insensitive or Angle-Dependent Reflection:
 By adjusting the design, dielectric mirrors can maintain high reflectivity even at non-normal angles of incidence, which is particularly useful in applications involving oblique light rays.

Applications of Dielectric Mirrors:
1.Laser Technology:
 In laser cavities, dielectric mirrors are used as highly reflective mirrors to bounce light back and forth, amplifying the laser beam. They are especially important in high-power lasers due to their low absorption and thermal stability.
2.Optical Filters and Interferometry:
 Used as part of optical filtering systems or in interferometers where precise control over reflected wavelengths is crucial.
3.Sensors and Instrumentation:
 In optical sensors and measurement devices where high reflectivity and low loss are essential for accurate readings.
4.Display Technology:
 In rear-projection TVs, head-up displays (HUDs), and other display systems where efficient reflection and control of light paths are required.
 In optical networks, dielectric mirrors are used for wavelength filtering, isolation, and multiplexing, enabling high-speed data transmission.
6.Optical Isolators and Circulators:
 In these devices, dielectric mirrors are employed to control the directionality of light propagation, enhancing system performance by preventing back reflections.

Design Considerations:
The performance of a dielectric mirror heavily relies on the choice of materials, the number of layers, and the thickness of each layer. The layers are typically quarter-wave thick, meaning they are a quarter of the wavelength of the light they are designed to reflect. This thickness ensures optimal constructive interference, leading to high reflectivity.

Product parameters

Mirror parameters


Gold coating, aluminum coating plus
dielectric coating, dielectric coating

Average reflectance


Enhanced single-band reflectivity

450nm、532nm、650nm、780nm @R>97%


JGS 2,high borosilicate glass

Surface parallelism


Clear aperture


Surface quality


Environmental testing



Protected Gold Mirrors

- Gold-coated Outer Mirrors: Because the surface texture of the gold-coated is very soft, it is necessary to coat the outer layer with a protective coat to prevent scratches and moisture. The gold-coated outer mirror is coated with silicon dioxide on the surface of the gold coat, which can protect the coat performance. The reflectivity in the 0.75 um - 20 um band is greater than 96%.

- Gold-coated Inner Mirrors: The inner mirror is protected by a chrome-coated gold coat surface. Reflection is reflected through the glass surface and then incident on the gold coat, so it is called internal reflection, and it is suitable for use in environments that do not require high spots. The reflectivity in the 0.75 um - 20 um band is greater than 96%.



Dielectric mirrors can have a very high reflectivity in a specific band, up to more than 99%. The dielectric mirrorsare conventionally available in single-point high reflection, such as 470 nm, 532 nm, 650 nm, 808 nm, 1064 nm. Broadband high reflection includes ranges such as 400-700 nm and 650-1200 nm.

Dielectric Mirror Design Parameters

 - Type: __Dielectric Mirror__

 - Primary Application: ____________________ (e.g., Laser cavity, beam steering, optical isolation)

 Reflectivity & Bandwidth

 - Target Wavelength(s): __________________ nm

 - Reflectance: _______% (Desired reflectivity within the target wavelength range)

 - Full Width at Half Maximum (FWHM): ± ______ nm (Width of the wavelength range where reflectivity is at least half of the peak value)

 Transmittance & Blocking

 - Outside Target Wavelength: _______% (Maximum allowed transmission outside the reflection band)

 - Blocking Range (if applicable): From ______ nm to ______ nm

 Coating Characteristics

 - Number of Layers: _______________________ (Approximate or as specified)

 - Coating Material(s): ____________________ (E.g., Ta2O5, SiO2, etc.)

 - Surface Quality: __________________________ (Scratch-Dig per MIL-PRF-13830B or equivalent)

 - Angular Stability: ± ______ ° (Angle range over which performance is maintained)

 Physical Characteristics

 - Size/Dimension: __________________________ mm (Diameter for round mirrors or dimensions for rectangular/square)

 - Substrate Material: ________________________ (E.g., BK7, fused silica, UV-grade fused silica, etc.)

 - Thickness: ______________________________ mm

 - Surface Flatness: λ/____ (RMS or PV)

 - Parallelism (for substrates): ± ______ °

    Environmental Requirements

 - Operating Temperature Range: From ______ °C to ______ °C

 - Storage Temperature Range: From ______ °C to ______ °C

 - Humidity Resistance: _______________________% RH

   Additional Requirements or Tests Special Instructions or Notes

- High Power Laser Damage Threshold: ______ W/cm² (If applicable)

 - Environmental Testing (humidity, temperature cycling): Yes / No

 - Custom Mounting or Coating Adhesion Test: __________________

   Special Instructions or Notes

 - __________________________________________________________

 - __________________________________________________________

This comprehensive list of specifications helps us manufacture a dielectric mirror tailored precisely to your application's requirements, ensuring high reflectivity at the desired wavelengths and minimal loss or transmission elsewhere. Upon receipt of this completed specification sheet, we can proceed with the design, coating, and fabrication process, followed by rigorous quality control and delivery of your custom dielectric mirror.