Low-loss small-mode passive waveguides and near-adiabatic tapers in BK7 glass

A detailed study of the Ag/sup +/-Na/sup +/ ion-exchange in BK7 glass and fabrication of low-loss (<0.2 dB/cm at lambda /sub 0/=1.3 mu m) single-mode waveguides using this technique are discussed. By postbaking the extremities of small-mode-size straight-surface guides, 5-mm-long near-adiabatic fiber-compatible tapered transitions with total fiber-device insertion losses below 0.8 dB in 16-mm-long devices, including the tapers at both ends, have been demonstrated.<
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