## 1 Introduction  
Optical sensing is important for monitoring the integrity of structures and the conditions of an environment, providing information on parameters, such as strain, temperature, pressure, humidity, vibration, and chemical species, among others. Fiber optic sensors are attractive due to their compactness, immunity to electromagnetic interference, resistance to harsh operating conditions, and the possibility to implement in point and/or distributed configurations. The spectral response of a fiber Bragg grating (FBG) changes--especially in terms of a wavelength shift--when it is exposed to a variation in strain, temperature, pressure, humidity, etc. As such, FBGs are a key enabling technology for fiber optic sensing [1; 2].  
FBG sensors lend themselves readily for multiplexing in wavelength, time, and space, thereby allowing the same interrogation system to monitor multiple sensors and achieve quasi-distributed (multipoint) sensing. Information from an FBG sensor is generally wavelength encoded, i.e., a change in the measurand (strain or temperature) causes a wavelength shift in its spectral response. This wavelength shift is then detected using an optical spectrum analyzer (OSA), or with some system that converts the wavelength shift into another detectable quantity, such as power (the system performs essentially a wavelength-to-power mapping). Although OSAs can provide a high resolution for detecting small wavelength shifts in various industrial (e.g., condition monitoring in oil and gas) and medical applications (e.g., medical wearables), they are bulky and provide low interrogation speeds [3; 4]. The latter is a significant limitation for interrogation in large capacity sensing networks where high-speed and/or real-time operation is required.  
Microwave photonics (MWP) is a field that focuses on exploiting photonic techniques and technologies for generating, processing, and analyzing/characterizing radio-frequency (RF) signals. Recently, there was growing interest in exploring the use of MWP for applications in fiber optic sensing, particularly as a means to achieve high-resolution and high-speed sensor interrogation (including sensors based on FBGs) [5; 6; 7; 8; 9; 10; 11]. Approaches include the use of FBG sensors in (1) opto-electronic oscillators (OEOs), (2) MWP filters, and (3) for generating chirped microwave waveforms. Wavelength shifts in the spectral response of the FBG sensors are translated into changes in the output frequency of OEOs, the power at a specific RF frequency (or set of RF frequencies) in a MWP filter, and shifts in the correlation peak associated with compressing chirped microwave waveforms. Most of the demonstrations thus far have focused on the interrogation of a single fiber optic sensor. However, simultaneous interrogation of multiple sensors with low crosstalk is important for quasi-distributed sensing or large capacity sensing networks. In this paper, we review our recent work on exploiting MWP techniques, particularly those based on MWP filters and chirped microwave waveform generation/compression, for simultaneous interrogation of multiple FBG-based sensors (an in-fiber Fabry-Perot (FP) cavity sensor based on FBGs, FBG sensors directly, and a linearly chirped FBG sensor) [12; 13].