Complex chemistry happening in Titan’s atmosphere produces optically thick organic hazes. These hazes not only affect the physical and chemical processes in Titan’s atmosphere and on its surface, but also impact our observations and understanding of Titan. Their optical and physical properties are essential inputs for modeling and analyzing observational data. Due to the lack of such information, Titan haze analogues, or tholins, have been prepared and characterized in the laboratory, and their properties have been used for atmospheric modeling and data analysis of remote sensing observations of Titan. Here, we perform laboratory simulations in a Titan relevant environment, analyze the resulting Titan haze analogues using vacuum Fourier transform infrared spectroscopy, and calculate the optical constants from the measured transmittance and reflectance spectra. We provide a new set of optical constants of Titan haze analogues produced with the PHAZER chamber, which can be utilized for analyzing the existing Cassini-Huygens data and future observations with the James Webb Space Telescope and the Dragonfly mission. This study establishes a feasible method to determine optical constants of haze analogues of other (exo)planetary bodies.