Morgan Advanced Ceramics, Rugby

Ceramic Reflectors for Solid State Laser Pumping Cavities and High Intensity lamps- Morgan Advanced Ceramics Sintox AL

Solid-state lasers include all optically pumped lasers in which the gain medium is a solid at room temperature.

Customer requirements will differ dependant upon the type of laser, laser rod, source radiation (and source power) being employed and the particular end use of the laser. All, however, require a high reflectance material to form the pumping chamber cavity surrounding the laser rod and lamp. The efficiency in transfer of radiation from the source to the laser rod (referred to as optical coupling) determines to a large extent the overall efficiency of the laser system. The cavity walls must therefore have a high reflectivity at the absorption bands of the laser material.

Ceramic reflectors supplied by Morgan Advanced Ceramics (MAC) work particularly well in Ruby and Nd:YAG laser pumping chambers and can be a highly cost effective alternative to metal coated reflectors. They are also used extensively as reflectors in housings for high intensity lamps. The reflectors are manufactured from Sintox AL, a high purity, porous (99.7% Al2O3) material, that: 

• resists chemical attack
• has high strength
• has a high reflectivity over a broad wavelength band
• has good thermal conductivity and
• excellent dimensional and electrical stability at all operating temperatures.

Independent tests on MAC's Sintox AL Alumina have shown reflectance figures in excess of 96% (typically 97-98%) over the 500 nm to 2000 nm wavelengths. The material provides a highly diffuse reflectance, behaving as a bulk reflector of the source radiation by both reflecting and refracting light back into the cavity.

Pump radiation that has a longer wavelength than the stimulated emission does not contribute to the laser output but does heat up the laser crystal, which causes optical distortions affecting the quality of the laser output. For this reason cavities are therefore often water or liquid cooled and so need to be able to withstand the erosive action of the fluid, absorb the generated heat and remain dimensionally stable.

MAC reflectors can be glazed both inside the cavity and around the outer edges using a highly reflective glaze that seals the ceramic against ingress of cooling fluids that may alter the refractive index, introduce impurities and reduce reflectance and efficiencies. Glazes can also act as filters and MAC's yellow glazed reflectors have been used successfully in certain applications. The visible yellow colour is complementary to the spectral colours violet and indigo and effectively absorbs these wavelengths up to around 450 nm.

Reflectance for Sintex AL and Yellow Laser Glaze

Reflectance for Sintox AL and Standard Laser Glaze

 

Reflectance for Sintox AL