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1.6 μm emission originated from Pr3+: (3F3,3F4)→3H4 transition in Pr3+- and Pr3+/Er3+-doped selenide glasses were investigated under an optical pump of a conventional 1480 nm laser diode. The measured peak wavelength and full width at half maximum of the fluorescent emission were ∼1650 and >100 nm, respectively. A moderate lifetime of the thermally coupled upper manifolds (∼212±5 μs) together with a high stimulated emission cross section of ∼(3±1)×10−20 cm2 promises to be useful for 1.6 μm band fiber-optic amplifier that can be pumped with an existing high-power laser diode. Codoping of Er3+ significantly enhanced the emission intensity by way of a nonradiative Er3+: 4I13/2→Pr3+: (3F3,3F4) energy transfer.

Er2O3‐doped PbO‐Bi2O3‐Ga2O3 glasses were prepared through the conventional melt‐quenching method, and the energy transfer mechanisms in Er3+ were investigated. The fluorescent emission at 2.73 μm, which is normally quenched in silicate glasses, became evident because of the low phonon energy of PbO‐Bi2O3‐Ga2O3 glasses. The measured lifetime of the upper level of 4I11/2 was 0.9 ms, and it decreased to ∼0.6 ms with increased Er3+ concentration. When the concentration of Er2O3 was 0.05 wt%, the coefficient of the cross‐relaxation rate for the 4I11/2 level was ∼18 times larger than that of the 4I13/2 level. On the other hand, the interaction parameter of energy migration was considerably larger for the 4I13/2 level (∼52 × 10−40 cm6·s−1) compared with the 4I11/2 level (∼3.1 × 10−40 cm6·s−1). Therefore, the major energy transfer mechanism associated with the 4I13/2 level was migration induced, whereas that for the 4I11/2 level was direct cross relaxation of 4I11/2:4I11/2→4F7/2:4I15/2.

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We propose and experimentally demonstrate an ultracompact transverse magnetic (TM) mode pass filter based on a rectangularly-shaped one-dimensional (1-D) photonic crystal silicon waveguide with an extremely high polarization extinction ratio (PER) of >30 dB and a low insertion loss (IL) of ~1 dB. The device structure of the TM mode-pass filter is numerically simulated using a three-dimensional (3-D) finite difference time domain (FDTD) method. The proposed device supports its fundamental TM mode only, whereas the transverse electric (TE) mode is reflected by the 1-D photonic crystals (PhCs). The measured PER of the fabricated TM mode-pass filter is ~34 dB, and the IL is about 1 dB. The entire device length is about 4 μm. Our simulation results predict that the device bandwidth of 30 dB PER is about 200 nm.