Possibility of optical cooling

Manuel Vogel

Ikuji Tsujikawa, Tsuyoshi Murao

The possibility of cooling by an optical process of ruby is pointed out. When C^<3+> ions in ruby are optically pumped by photons with a given energy and emit photons with higher energies, the lattice energy can be extracted as light, so that a cooling effect appears. If some possible heating effects did not overcome this cooling effect, the temperature would be actually reduced. Cooling rates and cooling capacities are given. If we could have light input powers 10^<-1> Watt or 10^<-2> Watt for optical pumping, it might be possible to cool from 80°K or 20°K to temperatures below 1°K, respectively. Technical problems and possible heating effects are discussed.

Ikuji Tsujikawa, Tsuyoshi Murao

The possibility of cooling by an optical process of ruby is pointed out. When Cr 3+ ions in ruby are optically pumped by photons with a given energy and emit photons with higher energies, the lattice energy can be extracted as light, so that a cooling effect appears. If some possible heating effects did not overcome this cooling effect, the temperature would be actually reduced. Cooling rates and cooling capacities are given. If we could have light input powers 10 -1 Watt or 10 -2 Watt for optical pumping, it might be possible to cool from 80°K or 20°K to temperatures below 1°K, respectively. Technical problems and possible heating effects are discussed.

Alexander J. Dunning

Larisa A. Nurtdinova, Vadim Vladimirovich Semashko, А. К. Наумов +2 more

The results of spectral kinetic studies of several fluoride crystals activated by Yb 3+ and Tm 3+ ions are presented, and their possible application as cooling elements of optical refrigerators is discussed. Optimum excitation conditions for the laser cooling effect in these crystals are found. The cooling efficiency is established to depend on the degree of order in the active medium.

Jean-Louis Basdevant, Jean Dalibard