Photonic Computing Using The Modified Signed-Digit Number Representation

Improving the precision of optically performed computations is a critical aspect of photonic computing. One possible method for improving precision is through the use of modified signed-digit (MSD) arithmetic. Optical implementation of MSD arithmetic offers several important advantages over other optical techniques such as the digital multiplication by analog convolution (DMAC) algorithm or the use of residue arithmetic. These advantages include the parallel pipeline flow of digits due to carry-free addition and subtraction, fixed-point as well as floating-point capability, and the potential for performing divisions. We present a brief description of the modified signed-digit number system and suggest one optical architecture for implementing MSD fixed-point addition, subtraction, and multiplication.