We report an intensity based fiber strain sensor using a long period grating (LPG) pair along with an in-line core mode
blocker. By sandwiching the core mode blocker fabricated by arc method between a LPG pair, an band-pass filter was
formed. Measured by optical power meter at one specific wavelength, the transmitted power was found to decrease as a
variation of axial strain is applied on one single LPFG, therefore we can measure the applied strain by measuring the
transmitted power. The measured response of voltage for change of strain was 6.37pV/ με.
We report a fiber sensor capable of simultaneously measuring temperature and strain. A fiber Bragg grating (FBG) was
incorporated in a Lyot fiber filter (LFF) by fusion splicing a section of high birefringence fiber (PM fiber) with an FBG
and then placing them between 2 polarizers. Measured in the transmission mode, the fringe resulted from the LFF and
the resonance wavelength dip of the FBG has different responses when a variation of temperature or strain is applied.
The proposed device can therefore measure both strain and temperature simultaneously.
We will discuss in this presentation a novel and simple erbium-doped fiber laser configuration for multi-wavelength oscillation at room temperature, in which a few-mode fiber Bragg grating was used as the wavelength-selective component. This multi-wavelength laser can be switched between dual- and triple-wavelength operations by properly adjusting polarization controller in the cavity. By using stain- or temperature-induced few-mode fiber grating, we also demonstrate a tunable multi-wavelength laser based on the proposed scheme. This multi-wavelength laser has the advantage of simple configuration, high stability, low cost and stable operation at room temperature.