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1 Abstract-A new scheme of oriented-hyperboloid -microlens (OHM) with passive alignment to achieve high polarized extinction ratio (PER) is proposed and demonstrated high efficiency coupling of high-power 980 nm pump lasers to polarization maintaining fibers (PMFs). Using an automatic grinding machine and a charge-coupled-device to precisely control and attain the required minor radius of curvature 4 -4.8 m, offset within 0.7 m, and axis orientation accuracy  1º, the OHM exhibited a high-average PER of 31.7 dB and a high-average coupling efficiency of 83.4%. For a 30 dB PER, the angular misalignment tolerance of the OHM was measured to be  2º. The unique advantage of the proposed OHM is passive alignment to achieve high PER by only aligning the OHM endface of the fast axis parallel to the axis of laser polarization. This newly developed OHM with unique passive alignment to achieve high polarization is beneficial for the applications of laser/PMF modules where mode polarization and high coupling efficiency are required for use in high precision fiber optic gyroscopes as well as many low-cost and high-performance lightwave interconnection applications.Index Terms-Passive alignment polarization-maintaining fiber, oriented hyperboloid microlens, fiber optic gyroscope.

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Two series of samples of single-layer IrMn and IrMn/FePd bilayer films, deposited on a single-crystal MgO substrate at different IrMn deposition temperatures (Ts = 300–700 °C), were investigated using magnetron sputtering. L12 ordering was revealed for the 30 nm-thick IrMn epitaxial (001) films with Ts ≥ 400 °C, determined by synchrotron radiation x-ray diffractometry (XRD). XRD results also provide evidence of the epitaxial growth of the IrMn films on MgO substrate. Increasing Ts from 400 to 700 °C monotonically increases the ordering parameter of L12 phases from 0.17 to 0.81. An in-plane exchange bias field (Heb) of 22 Oe is obtained in a 10 nm-thick FePd film that is deposited on the disordered IrMn films. As the L12 ordering of the IrMn layers increases, the Heb gradually decreases to 0 Oe, meaning that the exchange bias behavior vanishes. The increased surface roughness, revealed by atomic force microscopy, of the epitaxial IrMn layers with increasing Ts cannot be the main cause of the decrease in Heb due to the compensated surface spins regardless of the disordered and ordered (001) IrMn layers. The change of antiferromagnetic structure from the A1 to the L12 phase was correlated with the evolution of Heb.

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