  Using a ceramic thermoelectric heater, we show highly reproducible
fabrication of single-mode sub-wavelength silica tapers with ultra-low loss
level. The reproducibility of the process is studied statistically, leading to
an average taper transmission of 94%. The best tapers have a transmission
superior to 99%, above common level reached by other fabrication methods. The
taper profile is inspected along its length and closely follows the exponential
profile predicted by the model of Birks and Li. This high degree of control
over the taper shape allows a detailed analysis of the transition to the
single-mode regime during tapering. As an application of this fabrication
method, we present a micro-looped taper probe for evanescent coupling
experiments requiring fine spatial selectivity.
