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

Abstract

Instantaneous frequency measurement (IFM) of microwave signals is a fundamental functionality for applications ranging from electronic warfare to biomedical technology. Photonic techniques, and nonlinear optical interactions in particular, have the potential to broaden the frequency measurement range beyond the limits of electronic IFM systems. The key lies in efficiently harnessing optical mixing in an integrated nonlinear platform, with low losses. In this work, we exploit the low loss of a 35 cm long, thick silicon waveguide, to efficiently harness Kerr nonlinearity, and demonstrate the first on-chip four-wave mixing (FWM) based IFM system. We achieve a large 40 GHz measurement bandwidth and record-low measurement error. Finally, we discuss the future prospect of integrating the whole IFM system on a silicon chip to enable the first reconfigurable, broadband IFM receiver with low-latency.

Photonics for microwave measurements

“…A mixing between an optical signal modulated by a microwave signal and its replica with a given time delay could give rise to an optical power that is dependent of the microwave frequency. Thus, the IFM is realized by detecting the output power at the output of an optical mixing unit that can be implemented using two cascaded modulators or based on optical nonlinear effect such as four‐wave mixing (FWM) . In , a received microwave signal was equally divided into two parts and applied to two cascaded MZMs, to perform optical mixing.…”

Harnessing mode-selective nonlinear optics for on-chip multi-channel all-optical signal processing

“…Moreover, apart from nonlinear optical signal processing, the MSND can potentially be used in microwave photonics applications, and in particular, where nonlinear optics is used for microwave signal processing, such as XPM-based radio-frequency spectrum analysis 36 and FWM-based instantaneous frequency measurements. 37 In conclusion, the method of harnessing nonlinear optics in a mode-selective manner has the potential to scale to a higher number of channels and opens up a new degree of freedom in realizing various multi-channel all-optical signal processing and microwave photonics functionalities in an integrated photonic device.…”

Wideband dynamic microwave frequency identification system using a low-power ultracompact silicon photonic chip

“…It is important to note that this value is ∼10-fold lower than the optical power needed in on-chip IFM systems previously reported in literature (100 mW (ref. 12) or higher101115). Fibre-to-chip coupling is realized using on-chip grating couplers16.…”