Refractive index of phosphate-buffered saline in the telecom infrared C + L bands

The refractive index of phosphate-buffered saline (PBS) solutions, for concentrations ranging from 0 mol/L to 1.516 mol/L, was experimentally determined in the telecom C + L infrared bands, ranging from 1510 to 1620 nm, which is commonly used for silicon photonics biochemical sensors. The infrared measurements were performed with a silicon photonics arrayed waveguide sensor and compared with the optical visible range values measured with a handheld refractometer. An equation for the refractive index of PBS solutions as a function of wavelength and PBS concentration is presented. Moreover, the conductivity of the test solutions was determined and the relation between conductivity and refractive index was established, allowing for a fast, easy, cost-effective, indirect method of refractive index determination of PBS solutions. The data presented will enable more realistic simulation of optical biosensors and their precise experimental calibration.