Microwave photonic system for instantaneous frequency measurement based on principles of “frequency-amplitude” conversion in fiber Bragg grating and additional frequency separation

Photonic-Assisted Receivers for Instantaneous Microwave Frequency Measurement Based on Discriminators of Resonance Type

“…Detection in the "high" frequency region at the border of the FBG frequency range also leads to an increase in measurement error due to the nonlinear change in the frequency-to-power conversion and low signal power in the reflection channel. To solve this problem, it was proposed to detect the beat signal of the two-frequency components of the measured signal at an intermediate frequency by using an additional modulator with a fixed frequency to split each of the two-frequency radiation components to a difference frequency of 100 MHz [26]. Detection in this case is determined by the beat envelope of Detection in the "high" frequency region at the border of the FBG frequency range also leads to an increase in measurement error due to the nonlinear change in the frequency-topower conversion and low signal power in the reflection channel.…”

“…A block diagram describing the implementation of the proposed solution and a visual representation of the measured position of the signal harmonics is shown in Figure 8. IFM method with increased resolution at "high" frequencies: explanation of the operation principle (adapted from [26]). This solution, in comparison with solutions based on direct photodetection, makes it possible to reduce the effects of photodetection noise, namely, thermal, shot, and flicker noise, which are inherently low-frequency by nature, and in turn can increase the signalto-noise ratio (Figure 7) [26].…”

“…IFM method with increased resolution at "high" frequencies: explanation of the operation principle (adapted from [26]). This solution, in comparison with solutions based on direct photodetection, makes it possible to reduce the effects of photodetection noise, namely, thermal, shot, and flicker noise, which are inherently low-frequency by nature, and in turn can increase the signalto-noise ratio (Figure 7) [26]. As another solution to the measurement accuracy problem in the "low" frequency region, this paper presents the concept of separation of the measured frequencies at the center of the FBG slopes (linear section).…”

“…Technology/Method Frequency Range, GHz Measurement Error, GHz [23] FBG with concave profile 1-10 ±0.2 [24] Polarization maintaining FBG 0-17.2 ±0.12 [25] Gaussian FBG 0-10 ±0.08 [26] Gaussian FBG 0.04-20 n/a [27] Gaussian FBG 3-18 ±0.22…”

“…The key differences between implementation methods lie in the choice of the physical effect and the resonance type discriminator, which are the basis of IFM implementation. According to the measurement method, there are systems based on a fiber Bragg grating (FBG) [23][24][25][26][27], FBG with a phase shift (PS-FBG) [28][29][30][31], an optical microring resonator (MRR) [32][33][34][35][36], stimulated Brillouin scattering (SBS) [4,[37][38][39][40] and Fano resonance [41].…”