5-BIT SUBSTRATE GUIDED-WAVE TRUE-TIME DELAY MODULE WORKING UP TO 2.4 THZ WITH A PACKING DENSITY OF 2.5 LINES CM(2) FOR PHASED-ARRAY ANTENNAAPPLICATIONS/

A 5-bit true-time delay module is demonstrated. The combination 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 d elay step of 50 ps. The system design, device fabrication, and optimiz ation of the fanout intensity uniformity down to +/-10% among 32 fanou ts are addressed. The packing density of this device is 2.5 (delay lin es)/cm(2), which is the highest demonstrated thus far. A bandwidth of 2.4 THz is confirmed experimentally by employing a femtosecond laser a nd an ultrafast detector. (C) 1998 Society of Photo-Optical Instrument ation Engineers. [S0091-3286(98)03006-2].