Jinlong Li

Micro-Machined Optical Fiber Side-Cantilevers for Acceleration Measurement

We propose an accelerometer based on a micro-cantilever fabricated onto the side of a single mode optical fiber using a combination of ps-laser machining and focused ion beam (FIB) processing. FIB machining is also used to fabricate a 45° mirror onto the end of the fiber that is accurately aligned with optical fiber core. This provides a reliable means to optically address components attached to the side of the fiber, such as the cantilever. Using interferometry to accurately monitor the deflection of the side cantilever results in a device that is capable of measuring two-axis acceleration. Acceleration up to 6 g is measured with a resolution of ~0.01 g and a frequency range from dc to 500 Hz has been demonstrated. The cross-axis sensitivity is below −32 dB.

A miniaturized ferrule-top optical cantilever for vibration measurement

In this paper, we propose techniques to design and fabricate polymer micro-cantilevers for attachment onto the end of standard single mode fibers using laser machining. The polymer cantilever is fabricated by laser micro-machining a sheet of polymer into the required shape and then bonded onto the top of a ceramic ferrule by photo resist as a flat supporting and bonding layer. The dimension of resulting cantilever is ∼1.2 mm long, ∼300 μm wide, and 25 μm thick. In this work we describe the fabrication of single sensors, however the process could be scaled to offer a route towards mass production. Cantilever vibration caused by vibration signal are monitored by a DFB laser based phase interrogation system. Proof-of-concept experiments show that the sensor is capable of detecting vibration signal with a frequency range of 0–800Hz. By using thinner polymer sheet and machining longer cantilever, the frequency response range can be extended up to a few kHz.