High sensitivity miniature Mach-Zehnder-interferometer using micro-abrupt-tapers in a cladding-depressed strongly guiding fiber for a picoliter-volume microsensing

We demonstrate miniature Mach-Zehnder-interferometer with a device length of 179.5 μm using two micro-abrupt-tapers in a cladding-depressed strongly-guiding fiber. The index variation of 2×10-3 from a 6.3 picoliter optical liquid can cause 1.6 nm wavelength-shift.