of the photo diode illustrated in fig1 is positioned referring to fig2 a part 101 in which an absorbing layer 160 of the photo diode 100 is positioned is enlarged the waveguide 120 is formed on the substrate 110 and the intermediate layer 150 is formed at an upper end of a part at which the waveguide 120 ends in this case the absorbing layer 160 is formed at an upper end of the intermediate layer and the absorbing layer 160 is formed based on the branched point of the distal end of the waveguide 120 the absorbing layer 160 is formed and a p layer 170 is formed at an upper end of the absorbing layer 160 one antenna 140 is connected to the upper end of the p layer 170 to radiate electromagnetic waves the other antenna 140 is disposed at the upper end of the intermediate layer 150 which is spaced apart from the absorbing layer 160 by a predetermined interval to radiate electromagnetic waves accordingly the photo diode has a structure in which the waveguides 120 the antennas 140 the intermediate layer 150 the absorbing layer 160 and the p layer 170 are integrated on the substrate 110 in this case an area of the absorbing layer 160 is a significant factor for generating a broadband and high frequency terahertz continuous wave the.