IPAS Nonlinear Research featured in Nature Photonics
Nature Photonics have featured the nonlinear optics paper ‘Beyond expectations’ Opt. Lett. 34, 3577–3579 (2009) by Dr Shahraam Afshar Vahid and his group at IPAS as one of their Research Highlights from the recent literature.
Waveguides with high-refractive-index materials and subwavelength structures (HIS-WGs) are attractive for a wide variety of nonlinear devices, owing to their strong confinement of light. The nonlinear Schrödinger equation has traditionally been used to describe the propagation of nonlinear pulses in such waveguides, but the weak guidance approximation on which it is based breaks down in the presence of nonlinear effects. Recently, a generalized fully vectorial model of nonlinear pulse propagation was developed by Shahraam Afshar Vahid and co-workers from IPAS at the University of Adelaide in Australia, and their new description predicted larger values of the effective nonlinear coefficient and Raman gain for HIS-WG structures. Now, the same group has experimentally confirmed that these larger values and the model’s calculations are indeed correct for bismuth borosilicate suspended core fibres. The researchers measured the effective nonlinear coefficient of such fibres with diameters of 440, 507, 530 and 555 nm using the dual-continuous-wave method.
The results show that the Kerr nonlinearity agrees with the theoretical prediction of the vectorial model in the operating regime of HIS-WGs, confirming the difference in nonlinear coefficients between the standard model and the new model. The researchers attribute this difference to the high-index glass and subwavelength dimension of the fibre used. They say that the new model will help optimize the design and performance of future nonlinear HIS-WGs.