[OPTICAL REVIEW Vol. 6, No. 5 (1999) 424-432]
Optical Digital Fast Fourier Transform System
Masatomo SHIRAKAWA and Junji OHTSUBO*
Faculty of Engineering, Shizuoka University, 3-5-1, Johoku, Hamamatsu, 432-8561 Japan
(Received March 29, 1999; Accepted May 16, 1999)
A system for optical digital fast Fourier transform (FFT) is proposed. Data exchange, adder, and multiplier circuits required for the optical FFT system are designed. Each circuit contains the same basic element of an optical beam switch composed of a polarization rotator and a birefringent plate. In the FFT algorithm, butterfly switching for data exchange is important and the method of optical switching networks is very suitable for such operations. FFT calculation for one-dimensional data of a sinusoidal signal is experimentally demonstrated using the optical system. The throughput of the proposed system is estimated and its future perspective is discussed.
Key words : optical digital computing, fast Fourier transform, optical interconnects, free-space switching, polarization switch