The ever-increasing demand for enhanced data transmission capacity has led to the exploration of new transmission windows, beyond the C and L band typical in medium to long range optical fiber communications. Indeed, recent demonstrations have shown that although the fiber loss in the S-band is typically higher than the C-band, adoption of new amplifiers can enable a broad new transmission band that may be exploited both to extend the life of deployed fibers and to increase throughput in new space-division multiplexing fibers. In particular lower-wavelength bands are of interest to low-core count multi-core fibers where the strong wavelength dependence of inter-core crosstalk can place a limit on core-density for C/L-band transmission. Here, we describe a series of experiments, exploring S-, C and L-band transmission in single-mode and multi-core fibers covering bandwidths <150 nm and distances over 3000 km.