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In this paper, a highly sensitive fiber Bragg grating (FBG) interrogation system based on a dual-loop optoelectronic oscillator (OEO) with the enhanced Vernier effect has been proposed and experimentally demonstrated. Light reflected from the FBG sensor is used as the optical source of the OEO. By introducing dispersion in the OEO loop, the sensor information encoded in the FBG wavelength can be interrogated by detecting the frequency of microwave signal generated by the OEO loop. The dispersive media in OEO has two paths, one path is formed with a roll of dispersion compensation fiber (DCF), and the other path is formed with a roll of single-mode fiber (SMF). By designing the length of two paths with slightly difference, the Vernier effect is generated in the OEO. Since the dispersion of the two paths is opposite, an enhanced Vernier effect can be realized, which can significantly enhance the sensitivity. The experimental results prove the possibility of applying the concept of enhanced Vernier effect to the OEO for temperature sensing. The sensitivity is about 0.926 kHz/°C and 0.0912 kHz/°C for a single-loop OEO with DCF and SMF, respectively. By employing the enhanced Vernier effect, the sensitivity can be improved to 141.13 kHz/°C, which is estimated about 152.4 and 1547.5 times higher than that of the two single loops, respectively. Furthermore, sensitivity can be further improved by using a dispersive link with larger dispersion. [ABSTRACT FROM AUTHOR]

We demonstrate a proposed fiber optic sensor based on detecting the envelope of a Vernier microwave frequency comb (VMFC). A mode-locked fiber laser was employed as a microwave frequency comb source. A fiber ring, functioning as a sensor head as well as a microwave photonic filter, tailored the amplitude of each harmonic of the microwave frequency comb. By carefully designing the fiber ring length and the frequency separation of the microwave frequency comb, the Vernier effect is generated on the photodiode recovered microwave frequency comb after the laser pulses pass through the fiber ring. The sensing information can be deduced by tracking the envelope of the VMFC. The experimental results of a temperature sensing test show that the frequency shifts of the envelope peak have a good linear relationship with temperature variation. Furthermore, the sensitivity of the proposed sensor system is controllable. [ABSTRACT FROM AUTHOR]

An $8\times \,\,16$ wavelength selective switch (WSS) with full contentionless switching is proposed and experimentally demonstrated. Utilizing two chips of liquid crystal on silicon, the optical wavelengths can be switched, attenuated, or blocked among 8 input ports and 16 output ports. The maximum insertion loss is less than 14 dB; the bandwidth tuning range is from 50 to 5000 GHz. The attenuation range is from 0 to 15 dB, and the optical blocking value is greater than 27 dB. Compared with the previous reports, the $8\times16$ WSS proposed in this letter is a truly contentionless WSS device with the highest number of input and output ports. [ABSTRACT FROM AUTHOR]