Continuously tunable true-time delays with ultra-low settling time

Abstract

Ultra-fast, continuously tunable true-time delays are key components in many microwave and optical communications subsystems. In this paper, we introduce and demonstrate a new implementation method of a continuously tunable true-time delay featuring a settling time in the order of tens of picoseconds. Our solution relies on the splitting and combining of complementary phased shifted spectra (CPSS). It works for large bandwidth signals, has a low complexity, offers moderate losses, and can be fully integrated.

Instantaneous frequency measurement system using four-wave mixing in an ultra-compact long silicon waveguide

“…IFM sensitivity), compared to tuning a laser wavelength. A recent breakthrough in setting tunable time delay has achieved sub-nanosecond settling time 10 . This approach, comprising an optical delay interferometer and a phase modulator, was in fact highly prone to integration in a Si chip.…”

Instantaneous microwave frequency measurement using four-wave mixing in a chalcogenide chip

“…Since the delay required by the FWM IFM technique is platform-independent, such values would be sufficient for reproducing the current results. More recently, a new technique for achieving sub-nanosecond tunable, wideband true time delay was presented by Bonjour et al [33]. This used a complementary filter (e.g.…”

“…While achieving impressive results, this system required four lasers and two CWDMs, increasing cost and complexity. However, for our demonstration, the fact that the time delay could be potentially tuned in less than a nanosecond [33] opens up the possibility for ultra-fast reconfiguration of bandwidth and resolution, whereby a short time delay is used to acquire an initial estimate of the signal frequency, and within a few nanoseconds, the time delay is adjusted to achieve higher resolution in the frequency band of interest.…”

Low-error and broadband microwave frequency measurement in a silicon chip

“…The RF input signal is applied to the intensity modulator. The tunable time delay unit consists of an optical delay interferometer and a phase modulator [23]. Tuning of ∆t is achieved by varying the voltage input to the phase modulator.…”