Comparison of Peltier and anti-Stokes optical coolings

Anti-Stokes optical cooling is compared theoretically to Peltier cooling. The influence of reabsorption of fluorescence photons, parasitic absorption, and interaction length is discussed by using a simple modeling for the propagation of laser and fluorescence waves. An equivalence between anti-Stokes and Peltier coolings is presented, which shows that Peltier effect potentially exhibits a higher cooling coefficient but much larger thermal losses than anti-Stokes fluorescence. As a consequence, Peltier coolers are shown to be more effective for heat pump and high temperature operation (T>190 K), while anti-Stokes coolers could be used down to low cooling temperatures (around 70 K) especially if the cooling material could be operated at long pump wavelength. Moreover, if photons emitted at the anti-Stokes frequency are down converted to the laser frequency and recycled into the cooling medium, anti-Stokes cooling could reach very high efficiencies even in the low temperature regime, making this technique highly attractive for cooling down of small devices.