Direct process thermal line broadening in Tm : YAG

In celebrating the seminal paper by McCumber and Sturge on thermal line broadening by one- and two-phonon processes, I briefly revisit the ruby line width question and then investigate the thermal broadening of the 12604.3 cm-1 line of Tm : YAG using optical free induction decay and spectral hole burning. This transition has recently been used in demonstrations of high-density time/frequency domain storage and optical signal processing where thermally induced dephasing is an important issue limiting performance. © 2000 Elsevier Science B.V. All rights reserved.