Photonic Systems for Tunable Time-Delay

Time Domain Systems, Inc. proposes a novel true-time delay line for ultrashort optical pulses based on micro-size, layered, periodic, semiconductor structures. An unusual combination of properties causes nearly invariant transmission and large adjustable group delay for low-power, electromagnetic pulses. This is an extremely valuable and previously unavailable capability. For a picosecond pulse propagating near the photonic band edge of a 8 micron, one-dimensional CaAs/A1As layered structure the total group is well in excess of 100 microns. In addition, the total group delay accumulates linearly with the number of similar structures. With no detectable distortion of pulse shape. The group index for the optical pulse exhibits a dramatic increase, it is tunable, and many orders of magnitude more sensitive to variation in material refractive index than for bulk material. The combination of high transmission and large group index are long-sought phenomenon. Incorporation of these effects in a simple integrated circuit will make it possible to create extremely short, precise, and stable time delays. The delays produced by such a device would be on the order of 10s of picosecounds with a stability on the order of a few picosecounds.