Practical speed limits of free-space global holographic interconnects: time skew, jitter and turn-on delay

The speed limits imposed on free-space global interconnects are affected by factors that can be divided into three groups: geometric parameters of the optical system that determine the propagation time and time skew, emitter parameters (turn-on delay and timing jitter), and system requirements (fan-in in the detector and bit error rate). For 32 × 32 global interconnects, numerical estimations of light propagation time and timing skew are presented. Time delay and jitter in a diode laser are calculated. After evaluation of these parameters, the timing and synchronization methods (gate and strobe or time of flight) can be selected, and the ultimate clock frequency of the overall system can be determined. The decisive role of contrast ratio and fan-in in the detector plane in determining the practical modulation rate of the diode laser is discussed.