Five-bit substrate guided wave true-time delay module working up to 2.4 THz with a packing density of 2.5 lines/cm2 for phased array antenna applications

A 5-bit true-time delay module is demonstrated. The combi- nation of a 1-to-4 fiber beamsplitter and four 1-to-8 collinear guided-wave fanouts provides us with the required 32 surface-normal fanout beams with a delay step of 50 ps. The system design, device fabrication, and optimization of the fanout intensity uniformity down to 610% among 32 fanouts are addressed. The packing density of this device is 2.5 (delay lines)/cm 2 , which is the highest demonstrated thus far. A bandwidth of 2.4 THz is confirmed experimentally by employing a femtosecond laser and an ultrafast detector.