Nanotechnology is currently regarded as one of the fastest-growing technologies. Equipping students with some understanding of nanotechnology in relation to physics ideas may trigger their interest and inspire them to learn physics. This study is aimed to measure the refraction index of Cdots solution using the Gaussian beam and Tracker software. The method used in this research is quantitative descriptive method with the stages of research that include designing, construction, developing, and testing the measuring instrument. The procedure in this study begins by preparing the Cdots solution from cajuput oil (CJO) distillation wastes. The Cdots are then characterized using the UV-visible (UV-Vis), photoluminescence (PL), time resolved-PL (TRPL), and Fourier transform infrared (FTIR) spectroscopies. The Cdots solution is then put into a reaction tube with solution height variation. The violet/UV laser pointer is exposed upward towards the Cdots solution from the bottom of the reaction tube producing a Gaussian beam inside the reaction tube. The Gaussian beam is then photographed, which then the format is converted into a video format. The video format of the Gaussian beam is analyzed using the Tracker software. The characterizations of the Cdots show i) an absorption peak at a wavelength of 216.0 nm, ii) an emission peak at 512.29 nm indicating cyan luminescence, iii) an electronic lifetime of 51.3 ns, and iii) functional groups of O-H; C=C; and C=O. Moreover, the Gaussian beams are formed for various heights of the Cdots solution, i.e.: from 5.364 cm to 13.000 cm. Using the Tracker software, the value of the Cdots’ refraction index is 1.29 0.03, which is comparable to the refraction index of water. This measuring instrument has the potential to be used in high school physics classes and/or first-year university physics courses.