Electronically controlled agile lens-based broadband variable photonic delay line for photonic and radio frequency signal processing

Abstract

To the best of our knowledge, proposed for the first time is the design of an optically broadband variable photonic delay line (VPDL) using an electronically controlled variable focus lens (ECVFL), mirror motion, and beam-conditioned free-space laser beam propagation. This loss-minimized fiber-coupled VPDL design using micro-optic components has the ability to simultaneously provide optical attenuation controls and analog-mode high-resolution (subpicoseconds) continuous delays over a moderate (e.g., <5 ns) range of time delays. An example VPDL design using a liquid-based ECVFL demonstrates up to a 1 ns time-delay range with >10 dB optical attenuation controls. The proposed VPDL is deployed to demonstrate a two-tap RF notch filter with tuned notches at 854.04 and 855.19 MHz with 22.6 dB notch depth control via VPDL attenuation control operations. The proposed VPDL is useful in signal conditioning applications requiring fiber-coupled broadband light time delay and attenuation controls.