MODERN PHYSICS (PHYSICS 320) LAB
To excite Er3+ with a diode laser and obtain emission spectra
To observe up conversion and identify possible pathways
For reproducible spectra remember to always scan in the same direction.
Excite the 4F9/2 manifold of levels in Er3+ using the diode laser. Place the crystal on the axis of the spectrometer and excite the crystal from the side. Choose and align the optics so that the PMT signal is optimized. Do not exceed the limits on the PMT!!! With a hand-held spectrometer observe the emission to help determine the scan range. Obtain all of the emission lines from this manifold of levels. Explain the structure of the fluorescence from this manifold.
Use of a short focal length lens should increase the energy density of the beam in the crystal enough to produce up conversion indicated by green fluorescence from the 4S3/2 to the ground state. Record the emission spectrum from this manifold. From the energy level diagram for Er3+:YAlO, discuss the possible pathways that could result in occupation of the 4S3/2 state. Remember that energy must be conserved and spin selection rules must be observed.