The in situ high‐pressure behavior of the semiconductor antimony trioxide (Sb2O3) has been investigated by Raman spectroscopy techniques in a diamond anvil cell up to 20 GPa at room temperature. New peaks in the external lattice mode range emerged at a pressure above 8.6‐15 GPa, suggesting that the structural phase transition occurred. The pressure dependence of Raman frequencies was obtained. The band at 139 cm‐1 (assigned to group mode) has a pressure dependence of ‐0.475 cm‐1/GPa and reveals significant softening at high pressure. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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We propose and experimentally demonstrate a multi-wavelength thulium-doped fiber (TDF) laser based on all-fiber Mach-Zehnder interferometer (MZI) at 1.9 mm. Here a segment of 4 m single-mode TDF is pumped by 1568 nm fiber laser for 2 mm band optical gain. The MZI includes two cascaded 3 dB coupler. A segment of 3.5 m long un-pumped polarization-maintaining TDF and polarization controller (PC) are joined in the ring cavity to suppress the mode competition. Multi-wavelength lasers at 1.9 mm with wavelength number from one to four are obtained by adjusting the PC and the stability of output power of multi-wavelength fiber laser is analyzed.

The in situ high-pressure behavior of the semiconductor antimony trioxide (Sb2O3) is investigated by the Raman spectroscopy techniques and angle-dispersive synchrotron x-ray powder diffraction in a diamond anvil cell up to 31.5 and 30.7 GPa, respectively. New peaks observed in the external lattice mode range in the Raman spectra at 13.5 GPa suggest that the structural phase transition occurs. The group mode (140 cm −1 ) in Sb2O3 exhibits anomalous pressure dependence; that is, the frequency decreases gradually with the increasing pressure. High pressure synchrotron x-ray diffraction measurements at room temperature reveal that the transition from the orthorhombic structure to high-pressure new phase occurs at about 14.2 GPa, corresponding to the softening of the group optic mode (140 cm −1 ).

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