Laser cooling with optical temperature sensing in Er3+-doped tellurite-germanate glasses

A novel optical cooling route based on anti-Stokes fluorescence of H-2(11/2) state in Er3+-doped materials was proposed. The target temperature of the cooled solid could be monitored simultaneously via spectral inspection of the two green emissions from H-2(11/2) and S-4(3/2) excited states of Er3+. Here Er3+-doped tellurite-germanate glasses with various compositions were prepared. The temperature sensing properties and cooling abilities were systematically analyzed. It was found that all of the samples exhibit good temperature sensing performance and the net cooling could be achieved by properly choosing host materials and pumping wavelength estimated by the spectral measurements.