Modulation transfer in Doppler broadened Λ system and its application to frequency offset locking Y. B. Kale, A. Ray, N. Singh, Q. V. Lawande and B. N. Jagatap Eur. Phys. J. D, 61 1 (2011) 221-229 Published online: 05 November 2010 DOI: 10.1140/epjd/e2010-10220-2