Study On Anti-Stokes Fluorescent Cooling In Re³⁺-doped Glasses

A novel optical cooling route based on anti-Stokes fluorescence of2H11/2state 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 from2H11/2and4S3/2excited states of Er3+. Here Er3+-doped tellurite-germanate glasses with various compositions were prepared. The temperature sensing property and cooling ability 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.ZBLAN:Er3+glass was prepared. The cooling capability of Er3+in ZBLAN glass is evaluated from a theoretical point of view in considering the thermogenic effect by fluorescence quenching of each intermediate level between2H11/2level and4I15/2level of Er3+. The temperature-dependent non-radiative transition rate for each intermediate level of Er3+is calculated. The anti-Stokes fluorescence energy from2H11/2level is also calculated. The result indicates that the net cooling can be achieved by this sample system in the350-480K temperature range. Besides, the target temperature of the cooled solid can be monitored simultaneously via spectral inspection of the two green emissions of Er3+Since Eu3+may also exist anti-Stokes fluorescence cooling from different energy levels, we analyzed the Eu3+doped borate glass material. Radiative transition probabilities and the anti-Stokes fluorescence energy from7F1and7Fo level are calculated. The result indicates that the net cooling can be achieved by Eu3+doped borate glass material.