Absorption spectra of Er:YAG, Nd:YAG, Ruby and Ti:Sapphire laser crystals in the visible to the near Infrared
Abstract
Simple absorption spectroscopy using a broadband tungstenhalogen lamp as the light source and an Ocean Optics spectrometer as the detector was performed on four laser materials to characterize their optical properties in the visible to the near infrared region. The obtained absorption spectra of Er:YAG and Nd:YAG reveal multiple and narrow absorption lines while Ruby and Ti:Sapphire exhibit broad absorption bands. Er:YAG must have the most efficient pumping mechanism since it has the highest absorption coefficient values, more than twice the values of the other crystals. In addition, the fluorescence of Ruby was measured using two excitation sources: a He-Ne laser (λₚ = 542.95 nm) and a violet LED (λₚ = 411.61nm). The well-known peak of its narrow fluorescence at 694.36 nm is verified. The HeNe laser must be a better excitation source because it has higher quantum efficiency as compared to the violet LED.