In last ten years, research in the field of 2D materials has come into focus of scientific community because of their excellent electronic, optical and mechanical properties. Beside offering a variety topics for fundamental research, 2D materials are an excellent potential solution to the problems that industry is going to face in the near future, related to improvements of electronic devices based on silicon transistors where, due to their extremely small size, quantum mechanic tunneling effect will start to dominate and screen their usual working purpose. Few of the transition metal dichalcogenides are an excellent alternative for the silicon transistors, because crystals exhibit a crossover from an indirect- to a direct- gap semiconductor in the monolayer limit. Their general structure is MX_2, where M is transition metal and X is chalcogen element and their thickness is only three atomic layers. Because monolayers of transition metal dichalcogenides are not available in nature, they need to be isolated artificially form their bulk counterparts or synthesized. The synthesis of the high quality sample on a big scale is still an open question in the scientific community. This thesis will investigate synthesis quality of the transition metal dichalcogenides with optical techniques based on photoluminescence spectroscopy and Raman spectroscopy, as fast and non-invasive techniques for the characterization of sample quality, chemical composition, doping and sample purity. All samples will be synthesized by chemical vapor deposition technique, while optical characterization will be done immediately after the synthesis, so for the next sample synthesis, parameters could be modified according to the wanted sample properties. The focus is on the best known member of transition metal dichalcogenides family, molybdenum disulfide MoS_2, where its photoluminescence spectra give information on electronic structure, doping and straining of samples and Raman spectra gives information not only on chemical structure but also on sample thickness and interaction with wafer. Measurement of photoluminescence and Raman spectroscopy will be executed on the same experimental setup, with the laser excitation wavelength of 532 nm, and the goal of this thesis is to find the correlations of optical response with synthesis parameters, to understand which parameters are affecting growth morphology of MoS_2 and its quality, purity and defect level. By systematic synthesis and detailed analysis of spectra it has been seen that sodium is working as growth promotor and parameters of the CVD synthesis were optimized. It is shown that amount of argon flow and sulphur temperature have significant influence on the growth morphology of MoS_2 crystals, while furnace growth temperature has less impact on the morphology, but high influence on the sample quality and its electronic properties. Increasing the growth temperature, growth-induced strain has been induced to a single crystalline grains of MoS_2 as the main source of distinct optical properties in the form of exciton A emission lines redshift and by the softening of Raman modes. Finally, when morphology was improved and homogeneous, optical response was measured on a very small scale to see what is the level of uniformity of synthesized samples and defect variation on μm scale.