Neutron Damage in Distributed Bragg Reflectors and Microcavity Lasers.
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
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Distributed Bragg Reflectors DBRs grown on a gallium-arsenide substrate for a solid state mirror and a vertical cavity surface emitting laser VCSEL were subjected to a neutron fluence to determine the sensitivity of the DBRs. The samples were irradiated at Ohio State Universitys 500 kW research reactor. Relative and absolute reflectance measurements were taken before and after each irradiation over a spectral band of 530 880 nm. Relative reflectance measurements showed that the irradiation did not cause any spectral shift over seven decades of neutron fluences. The reflectivity of the DBRs decreased from their initial measurements after being irradiated. The reflectance decrease was correlated to the incident neutron fluence to determine a Messenger Spratt type of equation to predict the DBRs response. A radiation damage constant for the VCSEL and DBR mirror were determined to be 3.83x10exp13 NEUTRONSCM2 and 2.19x10exp13NEUTRONSCM2 respectively utilizing a 1 MeV equivalent Si neutron fluence.
- Lasers and Masers
- Radioactivity, Radioactive Wastes and Fission Products