| dc.description.abstract | For this project laser diodes facets have been coated with HR-coating, PHR-coating, and AR-coating. Three lasers have been coated, all had HR-coating on one facet, the other facet was uncoated for one laser, PHR-coated for one, and AR-coated for one.
The output power and voltage over the coated lasers have been measured. Uncoated lasers were used as a reference for the measurements to test the effect of the coatings.
The uncoated lasers had an average output effect of 15 mW.
The HR-uncoated lasers had an average output effect of 24 mW.
The HR-PHR lasers had an average output effect of 4 mW.
The HR-AR lasers had an average output effect of 30 mW.
The voltage over the uncoated lasers were constant at 1 V for high currents.The voltage over the coated lasers increased linearly at high currents. The differential series resistance for the coated lasers were calculated.
A method for coating the lasers were developed, the lasers were held vertically in the electron beam evaporator. The method involved putting the lasers between two pieces of Si wafer, then that stack was put on a clamp, the clamp was put into a holder, and another clamp was used to hold the laser in place.
To test the transmittance of the coatings, a FTIR spectrometer was used. The coatings were deposited on glass, GaAs, and GaSb. The coatings were the same design as the coating on the lasers.
The HR coating was made from Ge and SiO_{2}
, with six alternating layers, and SiO_{2}
was the first layer.
The PHR coating was made from TiO2 and Ge. It had two layers, TiO2 was the first layer.The AR coating was made from TiO2 and SiO2. It had two layers, with TiO2 as the first layer.
The transmittance of the coatings were simulated in Matlab. The measured transmittance was compared to the simulated transmittance. With glass as substrate, the measured transmittance were less than 7% off from the simulated transmittance, but some coatings on glass had transmittance exactly as simulated.
With GaAs and GaSb as substrates, the coatings had a measured transmittance that was from 12% to 25% off from the simulated transmittance, except one HR-coating that had a measured transmittance nearly exactly as simulated. | en |
