Forward discrete/inverse-discrete Fourier transform device and method for optical OFDM communication and transmitting and receiving apparatus comprising the device

A receiving apparatus for optical data communication in an optical OFDM system, the apparatus comprising:

• a forward discrete Fourier transform device for optically performing discrete Fourier transform on input optical OFDM symbols to demultiplex the symbols;
• N pulse carvers for receiving the demultiplexed optical OFDM symbols from the forward discrete Fourier transform device and outputting parallel optical data having a specific optical spectrum and pulse width;
• N photodiodes for converting the parallel optical data output from the pulse carvers into electric data;
• and
• a serializer for receiving the parallel electric data from the photodiodes and converting the parallel electric data into single serial data, wherein the forward discrete Fourier transform device comprises:
• a 1:N splitter for splitting an input optical OFDM symbol into N signals;
• a time delay array module for performing time delay on the signals from the 1:N splitter;
• N 1:N splitters for splitting signals output from the time delay array module;
• a phase shift delay array module for shifting phases of split signals from the 1:N splitters;
• N N:1 power couplers for coupling signals output from the phase shift delay array module;
• and
• a plurality of switches connected between an output of the time delay array module and the 1:N splitters or between outputs of the N:1 power couplers and a final output.

A forward discrete Fourier transform method for optical OFDM communication, the method comprising:

• (a′) splitting an input optical OFDM symbol into N signals;
• (b′) performing time delay on the N signals and outputting resultant signals;
• (c′) switching the signals output in step (b′)
• (d′) 1:N-splitting the signals switched in step (c′);
• (e′) shifting phases of the signals 1:N-split in step (d′) and outputting phase-shifted signals;
• and
• (f′) N:1-coupling the signals output in step (e′).