The optical properties of superconducting bolometers have been presented in YBa 2 Cu 3 O 7-x epitaxial films irradiated by a light emission diode with an 0.94 μm wavelength. The better response occurring in the resistive transition region has been shown and studied. A thermal fluctuation on the flux creep behavior can be employed to illustrate the nonlinearity optical current-voltage (I-V) characteristics in the low-resistive region. However, a dissipative mechanism of flux flow should be used in explaining the best response that reveals a linear I-V relation. Measurement of the bridges yielded the bolometric responsivity of approximately 77 V/W, by illuminating a 2 Hz dynamic signal with 0.15 mW. The noise equivalent power has been estimated as 3.2×10 -10 W Hz -0.5 .