Single crystal and polycrystalline CVD diamond for demanding optical applications

Fifty Years of Research and Development Coming to Fruition; Unraveling the Complex Interactions during Processing of Transparent Magnesium Aluminate (MgAl2O4) Spinel

“…Alkaline and alkali‐metal halides such as MgF 2 , and also glasses and glass‐ceramics, have lower mechanical and thermal properties . Transparent ceramics with competing properties to spinel include sapphire and polycrystalline ceramics such as Al 23 O 25 N 5 (AlON), Al 2 O 3 , MgO, cubic ZrO 2 , Y 2 O 3 , Y 2 Al 5 O 12 (YAG), and diamond . Sapphire and AlON have excellent mechanical and optical properties, but birefringence in sapphire requires single crystal use, and spinel has lower density, is easier to polish, and has lower production cost .…”

“…Polycrystalline MgO and Al 2 O 3 have excellent mechanical properties, but MgO has poor visible transmittance and polycrystalline Al 2 O 3 , although showing promise for IR windows and domes, is translucent in thick sections due to biregringence, even with nanometer‐sized grains . Single crystal and polycrystalline diamond produced by chemical vapor deposition have excellent optical and mechanical properties, but are difficult and expensive to fabricate and not yet commercially available …”

CVD diamond for high power laser applications

“…Single crystal diamond Fracture strength 450 MPa (Growth side) [10] 1030 MPa (Polished nucleation side) [9] 2860 MPa [7] Weibull modulus 15 (Growth side) [10] 11 (unpolished nucleation side) [9] 2.5 [7] Thermal conductivity (300K) >2000 W m -1 K -1 [11] 1800-2200 W m -1 K -1 [7] …”

“…These various materials have a range of properties that mean they need to be carefully selected for their application. Single crystal parts are available in smaller sizes than the polycrystalline components, however they have well controlled defect levels that can be optimized for specific applications, low birefringence and low scatter at all wavelengths 7 . In many applications of diamond it is more than just the optical properties that are important to its success.…”

Diamond — A Laser Engineer's Best Friend

“…It has the highest room temperature thermal conductivity of any bulk material, around an order of magnitude higher than many typical heat spreader materials, and two orders of magnitude higher than many optical engineering materials. It also has high fracture strength, allowing optics that must withstand stresses to be thinner, high Young's modulus that means it retains its shape well even under high loading, and a low coefficient of thermal expansion [1,2].…”