High Power and Ultrafast Optical Coatings

High Power Optical Coatings are optical coatings with a serious laser damage induced threshold (LIDT), designed to withstand exposure to high laser energies for high power applications such as high power lasers. The laser-induced damage threshold denotes the maximum laser fluence (for pulsed lasers, typically in J/cm²) or the maximum laser intensity (for continuous-wave lasers, typically in W/cm²) that the coating can endure before damage occurs. In various challenging contexts where high power light sources are present, high power optical coatings are crucial, as they perform the optical functions to alter the manner in which the optical components interact with light, while their high damage thresholds ensure the optical coatings will not degrade under the attacks of high power light sources. As technologies continue to progress, high power optical coatings with high LIDTs attract more and more interest and demands in application realms like medical applications, micro-machining, semi-conductor chip manufacturing, automotive, defense, and aerospace technologies, where the optical coatings become indispensable elements for various optical and laser components like mirrors, lenses, prisms, beamsplitters, etc. 

Ultrafast Optical Coatings are optical coatings designed for use in ultrafast optics. Examples include ultrafast-enhanced metallic coatings and femtoline low GDD dielectric coatings, which are engineered to offer high reflectance for ultrafast pulsed lasers while minimizing group delay dispersion to preserve the pulse shape. Since the pulse durations of ultrafast lasers (including ns, ps, fs) are very short, the power densities of the light are very high; therefore, optical coatings for ultrafast lasers must have a high laser damage threshold.

Hangzhou Shalom EO has professional experience in offering various custom optical coatings, including high power optical services. We provide designing and manufacturing coating services of high power optical coatings and ultrafast optical coatings with optimized laser damage threshold (LIDT) and low chromatic dispersion for applications of high power continuous wave (CW) lasers and ultrafast pulsed lasers. Broadband high power optical coatings, narrowband, beamsplitters, laser line v coatings, and other spectral functions are accessible. For measuring GDD, the Fast Innovations GOBI white light interferometer is utilized in Shalom EO.

Our high power and ultrafast laser optic coating catalog includes:

1) High Power HR Coatings for Laser Mirrors:

Shalom EO’s high-power dielectric reflection coatings enhance reflection while exhibiting an exceptional laser damage threshold. Our high power HR coatings highlight a laser damage threshold of 20J/cm2@1064nm, 10ns, 10Hz pulses, or 8J/cm2@532nm, 10ns, 10Hz. We are capable of tailoring power high reflection (HR) laser mirror coatings that accommodate various wavelengths and laser regimes. Optical coatings for pulsed lasers (e.g., nanosecond pulsed/picosecond pulsed/femtosecond pulsed lasers) are available, where the optical coatings, composed of dielectric thin-film construction, feature excellent resistance against intense radiation and thermal shock. High power optical coatings for continuous wave (CW), designed to dissipate heat fast and maintain stability under long exposure times, are also available. 

2) High Power PR Coatings for Laser Output Couplers:

Shalom EO's high power OC mirror coatings are partially reflective mirror coatings used to generate a laser beam and also catering to application scenarios of high laser energies. The coating is usually applied at the front surface of the OC mirror, and its reflectance is carefully chosen to balance output power with the desired laser characteristics, while the back side of the mirror is coated with an AR coating to minize loss. Highest laser damage threshold available for high power OC mirror coatings: 15J/cm2@1064nm, 10ns, 10Hz or 5J/cm2@532nm, 10ns, 10Hz.

3) High Power AR Coatings for Laser Lenses/Windows/Prisms, etc:

Shalom EO’s high-power anti-reflection dielectric coatings are designed to offer high transmission for optics operating under high power exposure. The thicknesses of each layer of the thin films are calculated using computer software to obtain superior thickness accuracies, which are closely related to the reflectivities of AR coatings. Highest laser damage threshold available for high power AR coatings: 15J/cm2@1064nm, 10ns, 10Hz or 5J/cm2@532nm, 10ns, 10Hz.

4) High Power Beamsplitter/Dichroic Coatings:

High-power optical coatings for beamsplitters and dichroic filters are available. These coatings split light into two components, where one component is transmitted, and one is reflected. Polarizing beamsplitter coatings split light based on their polarization state, non-polarizing beamsplitter coatings divide the intensities of light according to a percentage without changing the polarization state of light. Dichroic filter coatings are designed to reflect certain wavelengths of light while transmitting others. These coatings are excellent for a wide range of applications, like high-power laser polarizing beamsplitters (PBS) cubes.  Highest laser damage threshold available for high power dichroic/beamsplitter coatings: 15J/cm2@1064nm, 10ns, 10Hz or 5J/cm2@532nm, 10ns, 10Hz.

5) High Power Optical Filter Coating:

Multiple optical filter types are available. Because the optical filters have different types, the highest damage threshold of each type varies. An approximate estimate would be 15J/cm2@1064nm, 10ns, 10Hz, while the specific value depends on the design of the high power optical filter.

6) Low GDD Dielectric/Ultrafast-enhanced Silver/Chirped Mirror Coatings:

Optical coatings with low GDD are essential for maintaining the pulse shape of ultrafast and femtoline lasers. Shalom EO provides dielectric mirror coatings with minimized GDD, capable of handling pulse durations down to femtosecond scales are available. Ultrafast-enhanced silver coatings consisting of silver coatings and a dielectric overcoat are also available. The ultra-fast enhanced silver mirrors are a cheaper alternative for the low GDD dielectric mirror coating when broader wavebands and AOI ranges are more important than reflectivities. Highest laser damage threshold available for our low GDD dielectric coatings: 3J/cm2@800nm, 10ps, 100Hz or 4J/cm2@1030nm, 200ps, 100Hz.

Shalom EO also designs and manufactures chirped mirror coatings. These coatings are highly reflective optical coatings composed of alternating layers of dielectric materials with gradually changing thicknesses, contributing to a negative GDD value and compensating for dispersion when ultrafast pulsed lasers propagate in optics. 

For stringent inspection of the GDD values of the ultrafast coatings, Shalom EO engages the Ultrafast Innovations GOBI white light interferometer.

Shalom EO using Ultrafast Innovations GOBI white light interferometer for group delay dispersion measurement.

You can also visit our resource sector by clicking the bold text on the right to learn more about what is laser-induced damage threshold.

Application Notes:

Designing and crafting high-power or high laser damage coatings is a complex process of multiple procedures. At Hangzhou Shalom EO’s production branch, we specialize in offering high-power optical coatings and high power laser coating services through a combination of several optical coating processes, from substrate cleaning and coating material design to the ion-assisted deposition e-beam coating process and inspection.

1. Substrate Cleaning

Before and during the high power coating process, the substrate must be kept very clean and the surface free of residual particles and contaminants, which will lead to detrimental absorption of laser energies. Ultrasonic cleaning machines are leveraged in Shalom EO for cleaning the substrates before coating. 

   

2. Selecting Dielectric Coating Materials for High Power Laser Coatings

Drawing from the richness of our expert insights, Hangzhou Shalom EO’s coating technicians exploit the unique properties of different dielectric materials to design the high-power coatings that meet your LIDT requirement. These high power optical coatings are composed of alternating thin layers made of two materials with different refractive indices, one with a low refractive index and one with a high refractive index. 

The optical coating material selection depends on the application regimes. The high power coatings designed for pulsed lasers should be able to be resistant to dielectric breakdown from intense electromagnetic fields and be capable of withstanding the rapid thermal changes caused by the pulsed nature of the laser. Optical coatings for high power continuous wave (CW) lasers should not be prone to melting resulting from the absorption of the laser energies.

The materials choice depends on the wavelength of interest; the coating materials intended for optics used in the ultra-violet (UV) spectrum are different from those for optical components operating visible (VIS), or infrared (IR). Half-wave thickness thin film can be added to the thin film pile to increase the laser-induced damage threshold (LIDT). As mentioned above, high power dielectric coatings consist of dielectric refractive stacks. For the low-refractive index layers, silicon dioxide is a universal option; metal oxides are recommended for UV, visible, and NIR lasers. For the high refractive index layers, coating materials like titanium, tantalum, zirconium, hafnium, etc., are common for manufacturing high power optical coatings.

3. Ion Assisted Deposition E-beam (IAD E-beam) Coating Process 

Hangzhou Shalom EO harnesses the IAD e-beam coating process to enable the efficient and precision-controlled manufacturing of high power optical coatings. The IAD e-beam coating process. In the meticulous coating procedure, the essential factors like the rate of deposition, the temperature of the substrate, calibration of the thickness, preconditioning for material melt, and electron-gun sweeping are all tightly controlled to ensure smooth and even deposition. The entire coating process is carried out in our ISO-6 clean rooms to preserve the highest standard of cleanliness for the high power coating substrates. Furthermore, our vacuum coating chambers are also maintained free of excess materials as we cleanse them on regular regimes. In Shalom EO, the forefront coating machines and facilities are engaged in designing and crafting optical coating; we utilize these two coating machine modules at the current stage: SHINCRON MIC-1350TBN and Chengdu Guotai Vacuum Equipment GTF-900 which empower us to obtain the optimum outcome with each batch of optical coatings.

Shalom EO's SHINCRON MIC-1350TBN optical coating machine

4. Laser Damage Threshold Inspection

Two regimes can be used for testing the laser damage threshold. The first is a test until failure method, where the coatings under test are exposed to laser beams, and the laser power is either increased or decreased until damage occurs. Another method is to put the optical coating through a test with parameters specified by the manufacturer or customer, and then observe the capabilities of the optical coatings.

Shalom EO works with laboratories to conduct laser damage threshold tests for high power optical coatings, which ensures the reliable performance of our optical coatings. Test data and reports are available for our customer.