Photonic-Assisted Instantaneous Frequency Measurement System Based on a Scalable Structure

Abstract

We propose and demonstrate a new photonic-assisted instantaneous frequency measurement (IFM) system based on a scalable structure. By using multiple scalable modules, the proposed IFM system can achieve both large operating bandwidth and high measurement resolution. A rough measurement is given by a module with large operating bandwidth but low resolution. The final high resolution measurement is performed by other modules, which have smaller operating bandwidths but higher resolutions. By using four scalable modules simultaneously, the system achieves resolutions of ±0.1 and ±0.025 GHz for the 1-20 and 7−20 GHz frequency measurement ranges, respectively. By increasing the number of scalable modules, the resolution can be further improved.

Power-Independent Microwave Instantaneous Frequency Measurement Based on Combination of Brillouin Gain and Loss Spectra

“…Different fading responses were combined to create amplitude comparison function (ACF) for frequency measurement [7][8][9][10]. Although these schemes are power independent due to the power being removed by normalization of the reference arm in theory, the impacts of non-ideal responses of optical modulators such as their frequency chirp and finite extinction ratio (ER) could cause the ACF drift with the RF power [11]. Another kind of approaches were presented to measure RF frequency by using the frequency to time mapping technique [12].…”

Wideband High-Speed and High-Accuracy Instantaneous Frequency Measurement System

“…Using these phase detectors in the proposed structure to measure the LF signal phase differences, the incoming microwave signal frequency can be determined with an order of magnitude faster than the systems based on the frequency-to-time mapping technique and the frequency-to-power mapping technique with a kilometer-long fiber. This overcomes the latency problem in the reported photonic-assisted frequency measurement systems [4]- [14]. Table I shows the performance comparison of the proposed and reported frequency measurement systems without the latency problem.…”

“…There are a number of frequency measurement systems operated based on the frequency-to-power mapping technique that involve a kilometer-long fiber [12]- [14]. Using a long length of fiber for frequency measurement not only increases the system size but the system time delay is in the order of tens of microseconds.…”

Instantaneous Frequency Measurement with Reasonable Resolution and Simple Structure

“…where J n (•) is the nth-order Bessel function of the first kind. The signal [28] turns out as follows after going through a single-mode fiber…”

“…The schemes are implemented by using a dual-parallel MZM (DPMZM) [19], varying the wavelength [20][21][22], or using the Stimulated Brillouin Scattering (SBS) effect [23]. This problem can also be solved by increasing the slope of the ACF [24][25][26][27][28]. The systems reach the results of measurement frequency in the shortest time and do not cause a constraint on the system structure.…”