STOCHASTIC-THEORY OF NARROW HOLE-BURNING IN LOW-TEMPERATURE DILUTE RUBY

Transient hole-burning in low-temperature impurity-ion crystals is stu died using the model of two jump processes U-t = U-1(t) + U-2(t) (the random telegraph process U-1(t) and the uncorrelated jump process U-2( t) with a Lorentzian distribution of possible values) characterised by essentially different jump rates nu(1) much greater than nu(2) and di stribution widths sigma(1) much less than sigma(2) for the impurity io n optical transition frequency fluctuations U-t due to the bulk and th e frozen core host nuclear spins flipping. At short pump/probe pulse w idth T and short delay time tau(d)(tau(d), T much less than nu(2)(-1)) the calculated hole shape is narrow with the hole width determined by the U-1(t) process characteristic only while at long delay tau(d) gre ater than or equal to nu(2)(-1) it becomes a wide Lorentzian with the haftwidth 2 sigma(2). The theory fits the experimental data of Szabo e t al. well on narrow hole burning in ruby under low and high magnetic field, supposing the fluctuations U-1(t) to be rather slow (sigma(1)(2 )/nu(1)(2) = 0.5).