Abstract: The invention provides a close space annealing method and a method for preparing a perovskite film or a solar cell. The method includes: placing a substrate coated with the perovskite precursor film on a hot plate, the hot plate being in direct contact with the back face of the substrate; controlling the evaporated amount and residual amount of the solvent in the perovskite precursor film by controlling the temperature of the hot plate and the heating duration, so that the perovskite materials are crystallized into perovskite grains to form a perovskite intermediate-phase film; placing the perovskite intermediate-phase film on the permeable membrane with the back face of the substrate facing upward, continuing with heating, so that adjacent perovskite grains merge with each other; and raising the temperature of the hot plate and continuing with heating so that the perovskite grains form a perovskite light-absorbing layer.

Abstract: A method and an apparatus for self-calibration of an ONU receiver in a multi-wavelength PON system, said method including the initial physical layer scan of the receiver tuning range, distributed estimation of the down-stream wavelength channel drift with respect to the nominal standard-based wavelengths, and reporting the estimated downstream wavelength channel drift in the downstream Channel_Map message.

Abstract: A method and an apparatus for self-calibration of an ONU receiver in a multi-wavelength PON system, said method including the initial physical layer scan of the receiver tuning range, distributed estimation of the down-stream wavelength channel drift with respect to the nominal standard-based wavelengths, and reporting the estimated downstream wavelength channel drift in the downstream Channel_Map message.

Abstract: Disclosed are a method for prolonging the transmission distance of a passive optical network system and an optical line terminal. The method includes: acquiring each EDC tap coefficient corresponding to each ONU; and according to the each EDC tap coefficient corresponding to the each ONU, performing dispersion compensation respectively on an uplink signal sent from the each ONU. Thus the dispersion suffered by ONUs at different transmission distances can be pertinently compensated, so that the transmission distance of the system can be effectively prolonged.