A windowed optical calculation architecture and process that efficiently performs high speed multi-element multiply and accumulates on a digital data stream. A data point from a digital data stream is impressed onto an optical source to create an optical value. The optical value is split into a number of branches equaling the number of elements used in the calculation. In each branch, the optical value is modulated to reflect the coefficients in the calculation. Then, depending upon the branch, the optical value is delayed depending on its position in the calculation, with optical values at the beginning of the calculation being delayed longer than optical values at the end of the calculation. The outputs from the branches are coupled together to perform an optical sum, and passed to detection/analog-digital conversion circuitry to convert the optical result to a digital result.