By employing the optical phase conjugation (OPC) phenomenon, light can be guided through and focus inside the scattering medium. In this thesis, we investigate the effect of wavelength detune on the focusing of light inside a scattering medium. We implement the pseudospectral time-domain simulation technique (PSTD) to model the focusing of OPC light with the wavelength detuned: from 99.5% to 100.5%. By modeling light propagation through various geometrical conditions, we analyze the effect of wavelength detune on the focusing of CW light through a scattering medium. The simulation findings may provide helpful information for the focusing of OPC light with detuned wavelength.