T. Ohtsuki, S. Honkanen, N. Peyghambarian, M. Takahashi, Y. Kawamoto, J. Ingenhoff, A. Tervonen, K. Kadono,
Evanescent‐field amplification in Nd3+‐doped fluoride planar waveguide Applied Physics Letters. ,vol. 69, pp. 2012- 2014 ,(1996) ,
10.1063/1.116863