The goal of this work is to provide insight into the Dirac-band dispersion in Cd3As2 by means of optical spectroscopy. The recent recognition of the non-trivial election-band topology of Cd3As2 calls for a fresh look onto its optical properties. In this thesis, we report broadband optical investigations of Cd3As2. From the reflectivity data, measured from 6.3 meV to 2.7 eV (50 – 22 000 cm−1), we derive the optical conductivity σ(ω) that is determined by contributions from three different channels: free carriers, phonon modes, and interband transitions.[1] The Cd3As2 crystals were grown by the thermal evaporation method in the flow of argon from the pre-synthesized material. The synthesis of Cd3As2 was carried out by the direct reaction of stoichiometric amounts of Cd (99,999) and As (99,9999) in evacuated quartz ampoules at 750C. The growth process was performed in the quartz reactor placed in a two-zone furnace. The temperature in the evaporation zone of Cd3As2 was 520C and in the deposition zone it was 480C. The argon flow rate through the reactor was about 5 cm3 per minute during the entirely growth process and the argon flow was directed from the hot zone of the furnace towards its cold zone. Several well-faceted single crystals with dimensions of the faces of a few millimeters were grown in a few tens of hours. Resistivity and Hall measurements provide an electron density of ne = 6 × 1017 cm−3 (roughly independent of temperature), a metallic resistivity, and a mobility of μ = 8 × 104 cm2/Vs at 12 K. The lattice parameters obtained by X-ray diffraction pattern of powered single crystals of Cd3As2: a = b = 12.6539 Å and c =25.4586 Å with the tetragonal space group and are in good agreement with those reported before [2]. The investigated Cd3As2 single crystal had lateral dimensions of 2.5 mm by 3 mm and a thickness of 300 μm. It was cut out from a larger single crystal. The crystallographic axes of the sample were found by x-ray diffraction. The [001] axis was perpendicular to the sample’s largest surface. This surface was polished prior the optical measurements, which were performed for a few linear polarizations. The direct-current (dc) resistivity of this sample was characterized in-plane by standard four probe method. Both dc and optical measurements revealed an isotropic response with the (001)-plane. The optical reflectivity was measured from room temperatures down to 10 K with light polarized along different crystallographic directions. The spectra in the far-infrared (50 cm−1 – 1000 cm−1) were recorded by a Bruker IFS 113v Fourier-transform infrared spectrometer using an in-situ gold overfilling technique for reference measurements [3]. At higher frequencies (700 cm−1 – 22 000 cm−1) a Bruker Hyperion microscope attached to a Bruker Vertex 80v spectrometer was used. Here, either freshly evaporated gold mirrors or coated silver mirrors were utilized as references. We assume that the dc-resistivity and the optical conductivity of [001]-oriented n-doped (ne = 6×1017 cm−3) Cd3As2 are isotropic within the (001)-plane. The real part of the frequency-dependent conductivity follows a power law, σ1(ω) ∝ ω1.65, in a broad frequency range, 2000 to 8000 cm−1. We interpret this behavior as the manifestation of interband transitions between two Dirac bands with a sub-linear dispersion relation, E(k) ∝ |k|0.6. The Fermi velocity falls in the range between 1.04 × 106 and 1.46 × 106 cm/s, depending on the distance from the Dirac points. These values confirm previous reports based on ARPES and other experimental techniques.