  We present a simple lithographic method for fabrication of microresonator
devices at the optical fiber surface. First, we undress the predetermined
surface areas of a fiber segment from the polymer coating with a focused CO2
laser beam. Next, using the remaining coating as a mask, we etch the fiber in a
hydrofluoric acid solution. Finally, we completely undress the fiber segment
from coating to create a chain of silica bottle microresonators with nanoscale
radius variation (SNAP microresonators). We demonstrate the developed method by
fabrication of a chain of five 1 mm long and 30 nm high microresonators at the
surface of a 125 micron diameter optical fiber and a single 0.5 mm long and 291
nm high microresonator at the surface of a 38 micron diameter fiber. As another
application, we fabricate a rectangular 5 mm long SNAP microresonator at the
surface of a 38 micron diameter fiber and investigate its performance as a
miniature delay line. The propagation of a 100 ps pulse with 1 ns delay, 0.035c
velocity, and negligible dispersion is demonstrated. In contrast to the
previously developed approaches in SNAP technology, the developed method allows
the introduction of much larger fiber radius variation ranging from nanoscale
to microscale.
