A DTV transmitter includes a pre-processor pre-processing enhanced data, a data formatter generating enhanced data packets including the pre-processed enhanced data, and a multiplexer multiplexing the enhanced data packets with main data packets. The planar optical circuit 1 is composed of a filter 10 that can cause loss of variable wavelength dependence to signal light of a signal light wavelength band such that signal light input from a signal light input end 111 is caused to have loss at given wavelength dependent loss by filter 10 and is output from signal light output end 112. The forward face of the shank region may project outward from the forward face of the lower portion.