  We present an optically-detected mechanical accelerometer that achieves a
sensitivity of 100 ng/rtHz over a bandwidth of 10kHz and is traceable. We have
incorporated a Fabry-Perot fiber-optic micro-cavity that is currently capable
of measuring the test-mass displacement with sensitivities of 200 am/rtHz, and
whose length determination enables traceability to the International System of
Units (SI). The compact size and high mQ-product achieved combined with the
high sensitivity and simplicity of the implemented optical detection scheme
highlight our device and this category of accelerometers, outlining a path for
high sensitivity reference acceleration measurements and observations in
seismology and gravimetry.
