Semi-insulating 4H-polytype of Silicon Carbide (SiC) is a highly desirable wide bandgap semiconductor material for various applications in challenging environments owing to its exceptional characteristics such as high melting point, remarkable thermal conductivity, strong breakdown field, and excellent resistance to oxidation. In this study, we have presented a new doping method that utilizes a UV pulsed-laser emitting at 355 nm to dope SI 4H-SiC with Boron. Boric acid dissolved in water was used as a precursor to enable p-type doping where boron atoms diffused into the 4H-SiC substrate through photothermal heating by the laser. The mechanism of laser doping using a liquid boron precursor has been comprehensively explained and expanded upon in this study. Boron atoms create a dopant energy level of 0.3 eV in the wide bandgap of 4H-SiC. Diffusion of boron atoms into 4H-SiC modifies the electron densities in energy levels which in turn causes variation of the dynamic refractive index. Consequently, the optical properties of boron-doped samples are altered. Spectrophotometry measurements reveal the differences in the optical properties of undoped and boron-doped samples for the MWIR range. The laser doping process was evaluated by measuring the change in the index of refraction for the boron-doped versus undoped samples. Additional experiments are performed to evaluate the dopant concentration needed to produce a large index change of 0.2-0.3. Laser-doped samples will be used in interferometric or other devices that exploit the unusual large optically-controlled refractive index change of the dopant layer upon illumination with ? ~ 0.30 eV light.