Multiple radio frequency measurements with an improved frequency resolution based on stimulated Brillouin scattering with a reduced gain bandwidth

Abstract

A photonic-assisted multiple radio frequency (RF) measurement approach based on stimulated Brillouin scattering (SBS) and frequency-to-time mapping with high accuracy and high frequency resolution is reported. A two-tone signal is a single-sideband (SSB) modulated on an optical carrier via a dual-parallel Mach–Zehnder modulator to construct one SBS gain and two SBS losses for SBS gain bandwidth reduction. The unknown RF signal is also SSB modulated on a carrier that has been modulated by a sweep signal, thus the unknown RF signal is converted to a sweep optical signal along with the sweep optical carrier. The bandwidth-reduced SBS gain spectrum is detected by the sweep optical signals at different specific time, mapping the RF frequencies to the time domain. An experiment is performed. RF frequencies from 0.3 GHz to 7.6 GHz are simultaneously measured with a root mean square error of less than 1 MHz. In addition, the frequency resolution of the measurement can be much lower than 10 MHz, which is now the best result in the RF frequency measurement methods employing the SBS effect.

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

“…The frequency comb breaks out the limitation error of Brillouin method. In reference [21,[28][29], the error of frequency measurement is mainly determined by the line width of BGS. In order to reduce the error, an additional method of reducing the BGS line width has to be introduced.…”

Real‐Time and High‐Accuracy Microwave Frequency Identification Based on Ultra‐Wideband Optical Chirp Chain Transient SBS Effect

“…SBS based [23] ≈150 μs × 250 0-20 √ √ [24] 500 ms × 10 0.3-7.6 √ √ [25] Seconds order × 30 1-9 √ √ [26] 600 μs × 1 3 8 × × [27] Hundreds μs × 20 27 √ √ [28] 500 relationship between 𝛼 and ∆Ω is linear (as determined previously by both experiment and simulation), so that accurate measurements can be realized for different measurement ranges and instantaneous bandwidths. We can conclude from Figure 15 that frequencies anywhere in the range 0-20 GHz can be accurately measured by varying 𝜈 1 and 𝜈 N .…”

“…[22] Therefore, in typical SBS-based photonics-assisted microwave measurements, the Brillouin spectrum can be used as a tunable ultra-narrow bandwidth photonic filter with a spectral width of ≈30 MHz (in standard optical fiber). As shown in Figure 1a, the typical operating principle is that the microwave frequency can be measured by the Brillouin spectrum frequency sweep, such as sweeping a microwave-modulated optical frequency shifter [23,24] or else by directly sweeping the central frequency of the Brillouin spectrum. [25][26][27][28] Since the narrow bandwidth is a characteristic of the Brillouin spectrum, the frequency measurement accuracy is improved to 30 MHz.…”

“…[25][26][27][28] Since the narrow bandwidth is a characteristic of the Brillouin spectrum, the frequency measurement accuracy is improved to 30 MHz. [25] Moreover, the measurement accuracy can be further improved by reducing the Brillouin spectral width by superimposing Brillouin gain and loss spectra, [24] or by building steep amplitude-comparison-function curves with ultra-narrowband filter responses. [26] In the latest research, the frequency accuracy has been improved to 1 MHz.…”

Broadband Microwave Photonic Frequency Measurement Based on Optical Spectrum Manipulation and Stimulated Brillouin Scattering

“…The principle of the frequency measurement method based on SBS [9], [10], [17], [27], [28] is that the SBS is used to generate selective gain or loss on the first-order sideband of phase-modulated signal which is related to the frequency of the signal to be measured, so as to complete the PM-to-AM conversion, build the mapping relationship between frequency and power, and finally obtain the frequency to be measured by detecting the microwave signal power after frequency beating. .…”