1. E. Snitzer; ‘Optical maser action of Nd3+ in a barium crown glass’, Physical Review Letters, 72, 36, 1961.
2. See for example N. Langford and A. I. Ferguson; ‘Rare earth doped silica fibre lasers’, Ch. 3 in Principles of Modern Optical Systems, Vol. II, Eds. I. Andonovic and D. Uttamchandani, Artec House, Boston, 1993.
3. See for example G. P. Agrawal; Non-Linear Optical Fibres, Academic Press, New York, 1987.
4. S. B. Poole, D. N. Payne and M. E. Fermann; ‘Fabrication of low loss optical fibres containing rare earth ions’, Electronics Letters, 21, 737, 1985.
5. K. Koo, A. Kersey and F. Bucholtz; Postdeadline paper PD41, ‘Fibre Bragg grating laser magnetometer’ in the Proceedings of the Conference on Lasers and Electro-Optics, Baltimore, USA, 1995.