Liquid Phase index from refractive group index Reference phase index at 1310nm ng dn/dλ*(μm-1) n n* Water 1.34279 -0.015 1.32211 1.3224 Ethanol 1.36463 -0.00542 1.35297 1.3532

* Obtained from [12,13]. Table 1: Comparison of refractive indices.