Microwave Photonic Temperature Sensing Based on Fourier Domain Mode-Locked OEO and Temperature-to-Time Mapping

Broadband microwave signal generation and processing based on optical domain controlling

“…PM, phase modulator; FP filter, Fabry-Perot optical filter; OC, optical circulator; BPF, Bandpass filter; EA, Electrical amplifier; OSC: oscilloscope. [19] Figure 8 shows the proposed microwave photonic temperature sensor based on a pulsed Fourier domain mode-locked OEO (FDML OEO) and temperature-to-time mapping [19] . Compare to traditional FDML OEO, the proposed scheme has three differences.…”

“…In order to analyze the frequency information of oscillation signal, an electrical spectrum analyzer (ESA) with large bandwidth is indispensable, which increases the cost of the system. We have reported novel microwave temperature sensors based on temperature-to-time mapping with the help of a pulsed Fourier domain mode locked OEO [19] or optical spectral filtering and heterodyne beating [20] . The variation of interrogated temperature is mapped to time interval of the oscillation microwave pulses in the time domain, and only low-speed time-domain sampling devices are needed to capture and analyze the time interval of the output microwave pulses.…”

“…(b) Experimental data and linear fitting of the temperature-to-time mapping relationship from 35°C to 37°C with a temperature step of 0.1°C. (c) Pulse width of the generated output pulse when the temperature is at 35°C [19].…”

Optical fiber temperature sensor based on beat frequency and Vernier effect of fiber ring resonator composite cavity

“…The frequency comb Vernier spectroscopy is used to obtain sensing information by tracking wavelength shift in the optical domain, which relies on complex and expensive optical devices. The demodulation technology of microwave photonic fiber sensing is usually realized by optoelectronic oscillator, which requires an optoelectronic modulator for modulation [20,21], and the system structure is complex. The laser beat frequency demodulation technology is relatively simple in structure and low in cost.…”