For a CW Ti: sapphire rins laser without optical diode, there are two output beams corresponding to two oppositely traveling waves in the cavity. Unidirectional operation is obtained when one of the output beams is reflected back into the cavity. In this paper, the experimental results of an unidirectional operation laser, includins input-output curve, the power ratio of the two oppositely travelins waves under different coupler transittunces and pump levels, the tuning characteristics with a prism in the external cavity, and the narrowing of the output spectrum with etalons, are given.