Abstract: In quantum mechanics, a measurement of one variable is accompanied by back-action on the conjugate variable. In the particular case of an optical displacement measurement, the quantum back-action is radiation pressure shot noise (RPSN), the Poissonian noise in the momentum transferred by reflecting photons. The goal of observing RPSN is motivated by basic questions about quantum measurements, as well as by the fact that RPSN is expected to limit the performance of next-generation gravitational-wave observatories (though squeezed light can be used to mitigate the effect). In an attempt to measure RPSN, we have made an optomechanical device consisting of a fiberbased optical cavity containing a silicon nitiride membrane. In comparison with typical free-space cavities, the fiber-cavity’s small mode size (10 micron waist, 80 micron length) allows the use of smaller, lighter membranes and increases the cavity-membrane linear coupling to 3 GHz/nm. This device is also intrinsically fiber-coupled and uses glass ferrules or v-grooves for passive alignment; these improvements will greatly simplify the use of optomechanical systems, particularly in cryogenic settings. At room temperature, we expect these devices to be able to detect the shot noise of radiation pressure.