Search

We demonstrate a compact in-fiber integrated microresonator based on a silica microsphere and microstructure fiber. Whispering-gallery-modes (WGMs) are effectively excited through evanescent field coupling between the silica microsphere and one of the input tube waveguides of negative curvature fiber. The WGM spectrum with the Q-factor of ∼2.56 × 103 and the extinction ratio of ∼15.2 dB is achieved. The transmission spectra evolution for 5 h reveals the long-term stability of WGM excitation. The experimental results indicate that the in-fiber integrated resonator has the advantages of high stability, high integration, robustness, alignment-free assembly structure, and low cost, motivating potential applications in the lab-in-fiber platform.

The development of simple and sensitive sensors with the capability of simultaneously detecting magnetic field intensity and its direction in three-dimensional (3D) space is a technical imperative for magnetic field detection. In this paper, we first demonstrated the mechanism of anisotropic manipulation of ferromagnetism nanoparticles (FMNPs) in a non-continuous magnetic fluid film with the aid of varying magnetic fields. Second, based on the anisotropic distribution of the FMNPs around an optical fiber, we fabricated a vector magnetometer with a direction error of ±1.9° and an intensity sensitivity of 222.0 pm/mT, respectively. The sensing mechanism relies on the magnetism-controllable effective refractive index modification of asymmetric cladding modes in an in-line fiber-optic Mach-Zehnder interferometer. Compared to the previously reported intensity-based magnetometers, the as-fabricated magnetometer also provides an avenue to monitor the vector direction of the magnetic field in 3D space.

We investigated the fiber Bragg grating (FBG) thermal response in space vacuum thermal environment. The FBGs were packaged with 6061-T6 aluminum. The liquid nitrogen immersion experiment results show that its wavelength shift standard deviation is 0.76 pm for 217 h. The combination effect of vacuum and cryogenic temperature was studied by thermal cycling process in space environment simulator. The FBG sensors show accuracy better than 2% full scale, and the hysteresis errors are below 1%. It proves that these metal packaged FBG sensors can survive and meet the requirement of space measurement.