Demonstration of all-optical true-time delay for a multiaperture free-space laser-communication transmitter using a rapidly programmable 8-bit chip-scale module

Planar beam-steering apertures for laser-transmitter applications require a true-time-delay (TTD) subsystem for enhanced data-rate performance. The requirements for such a subsystem depend on the overall aperture size, field-of-view, beam-steering switching speed, and data pulse duration. The reprogramming speed of this 8-bit module (1-ps minimum resolvable time increment, and 0-256-ps range) is measured to be /spl sim/400 μs, and the upper limit of the dispersion produced by the device is measured to be 0.125 ps/cm/spl middot/nm. Using a TTD chip-scale module for temporal simultaneity, a demonstration of free-space 1.55-μm beam-steering over /spl plusmn/30/spl deg/ field-of-view is reported, wherein 2-ps-long laser pulses are emitted from two subapertures.