Optically produced true-time delays for phased antenna arrays

Abstract

A device is described for generating true-time delays optically for microwave signals used in beam steering and beam shaping in phased-array antennas. The device can be adapted to provide delays from picoseconds to nanoseconds. A single, compact unit should provide parallel delays for more than 64 independent antenna elements with a greater than 6-bit resolution. The time delays are produced by multiple reflections in a mirror configuration with continuous refocusing. A single spatial light modulator selects independent optical path lengths for each of the parallel antenna elements. Amplitude control for beam shaping can be integrated into the device. The unit can be made rugged for harsh environments by use of solid-block construction. The operation of the true-time delay device is described, along with the overall system configuration. Preliminary experimental data are given.

Demonstration of a quartic cell, a free-space true-time-delay device based on the white cell

“…Detailed descriptions of these White-cell-based designs are available elsewhere [25], [26], [28]- [32], so we only give a general outline here.…”

Optical true time delay for phased-array antennas: demonstration of a quadratic White cell

“…It has the added feature of refocusing the beam to a new spot on each pass. In a previous paper 23 we proposed several optical TTD devices, in which we adapted the White cell to TTD by replacing one of the mirrors with a spatial light modulator ͑SLM͒ and then using the SLM to control the number of times the light beams bounced and thus the time delay. In that linear demonstration, the number of delays was proportional to the number of bounces.…”

Passively mode-locked Nd:YVO4 multipass resonator with low repetition rate

“…The total number of bounces depend on the spacing 2δ between the centers of the curvature of the mirror B and C and the size of the mirror A [12]. crystal with a size of 4×4×8 mm 3 , which is pumped via a dichroic beam splitter (DCBS) and an output coupler (OC) by 20 W from a high power 808 nm, 600 µm diameter, 0.13 N.A.…”