Reconfigurable Delay Time Polymer Planar Lightwave Circuit for an X-band Phased-Array Antenna Demonstration

A 4-bit polymer optoelectronic true-time delay (TTD) device is demonstrated. The planar lightwave circuit (PLC) is composed of monolithically integrated low-loss passive polymer waveguide delay lines and five cascaded 2 times 2 polymer thermooptic switches. Waveguide junction offsets and air trenches simultaneously reduce the bending loss and device area. Simulations are used to optimize the trench and offset structures for fabrication. The 16 time delays generated by the device are measured to be in the range from 0 to 177 ps in 11.8-ps increments. The packaged PLC has an insertion loss of up to 14.9 dB, and the delay switching speed is 2 ms. An eight-element X-band phased-array antenna system is constructed to demonstrate the beam-steering capabilities of the 4-bit-delay devices. The TTD devices are shown to steer the far-field radiation pattern between 0deg and -14.5deg