Abstract

Second harmonic generation (SHG) in optical glass fibres [1] is an unexpected but nevertheless potentially useful nonlinear phenomenon. Optical fibres offer several advantages in SHG over other devices. Firstly the combination of a long interaction length together with the high intensity possible in a small core permits the relatively small non-linear effects in glasses to be effectively utilised. Furthermore, the self-writing process of SHG in optical fibres may provide an automatic phase matching [2] which is vital in any efficient wave-mixing process. However since observation of efficient SHG in fibres by Österberg [3], there has been very little progress in increasing the efficiency of SHG in fibres, with the highest reported efficiency to date being 13% by Farries et al [4]. Whilst many theories have been proposed as to this efficiency limit, we present here, for the first time, an investigation of the effects of the third order nonlinearity on the second harmonic generation efficiency.

© 1993 Optical Society of America