A racetrack waveguide resonator filter was fabricated by ion exchange technology in K9 optical glass. The filter responses of the waveguide resonator were measured with two polarized input lightwaves. The polarization-dependent characteristics of the waveguide resonator were analyzed, and the results of effective indices of n_(TE)=1.5721 and n_(TM)=1.5548, coupling ratios of r_(TE)=0.731 and r_(TM)=0.761, and losses of 'alpha'_(TE)=4.35 dB/cm and 'alpha'_(TM)=6.05 dB/cm were obtained for transverse electric (TE) and transverse magnetic (TM) modes, respectively. The causes of large loss and effective index differences between TE and TM modes were discussed.