In this letter, we propose and realize a new method that utilizes a dispersion-shifted fiber having compound compositions with different temperature coefficients in core to simultaneously measure the distributed strain and temperature based on Brillouin frequency shift. In a 3682-m sensing length of large-effective-area nonzero dispersion-shifted fiber, a temperature resolution of 5 C, a strain resolution of 60 , and a spatial resolution of 2 m are achieved simultaneously.Index Terms-BOTDR, Brillouin frequency shift, dispersion-shifted fiber. R ECENTLY, the fiber-distributed strain/temperature measurement based on the Brillouin scattering effect has been intensively studied. The Brillouin frequency shift is dependent on the temperature and strain conditions of the optical fiber, which provides the basis for a sensing technique capable of detecting these two parameters. The challenge, then, is to develop a technique to distinguish their individual contributions to the change in the Brillouin frequency of the optical fiber and to avoid the cross-sensitivity problem. Several techniques have been reported to accomplish the simultaneous measurement of fiber strain and temperature. In these methods, the one that uses a half of the fiber isolated from the effects of strain for temperature sensing [1], and another one that utilizes the fiber Bragg gratings combined with optical fiber [2] both require rather complicated sensing structure. Another technique that simultaneously measures the Brillouin power and frequency shift can achieve the fully distributed measurement of strain and temperature [3], but the temperature resolution is limited by the power measurement accuracy ( 0.013 dB for 1 C), which is very difficult to reach 0.05 dB over a considerable length of fiber and is very sensitive to environment.In this letter, we propose a new method that utilizes a dispersion-shifted fiber having compound compositions with different temperature coefficients in core as the sensing fiber to measure the distributed strain and temperature simultaneously. To prove this concept, the large-effective-area nonzero-dispersion-shifted fiber (LEAF), which has been reported to have multiple compositions in the fiber core [4] and now intensively deployed in Manuscript dense wavelength-division-multiplexing (DWDM) networks, is chosen as the test fiber. This technique needs only the measurement of Brillouin frequency shifts of the Brillouin spectra and can accomplish the high resolution and accuracy of temperature and strain measurement without modifying the sensing fiber.If an optical fiber has compound compositions in core, the multipeak structure in Brillouin spectrum of this optical fiber is arisen from the different acoustic velocities, which are due to different compositions or doping concentrations in the core [5]. From a previous experiment [3], the Brillouin frequency shift is dependent on strain and temperature of the standard single-mode fiber (SMF). In the case of an optical fiber with compound compositions in the core, the Brill...

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The broad-area rectangular-shaped and stadiumshaped VCSELs with nearly the same aspect ratio are designed to explore the influence of lateral boundary shapes on polarization states and lasing spectra with large detuning by cryogenic cooling. For the rectangular-shaped VCSEL, the lasing modes usually exhibit linearly polarized state and their far-field emissions mainly concentrate on four diagonal directions. On the other hand, the lasing modes of the stadium-shaped VCSEL generally display two orthogonally polarized states and their far-field emissions extensively spread on azimuthal directions. More intriguingly, the lasing spectra of the two devices clearly manifest the features of the energy-level distribution in regular and chaotic quantum billiards, respectively.