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.
Micro-cantilever sensors have shown great promise in a wide range of application are as including chemical and biological sensing. However, many of these devices are based upon a sensor ‘chip’ that requires careful alignment between the cantilever and the read-out system, which can be challenging. Furthermore, optical interrogation typically involves a bulky free-space system. Optical fibre addressed cantilevers have been reported previously in the literature and in this paper we propose techniques to design and fabricate polymer micro-cantilevers for attachment onto the end of standard single mode fibres using laser machining. Low-cost optical sources and a fibre coupled spectrometer are employed to monitor the cantilever deflection and therefore observe biological binding between a species of interest and an activated cantilever. Proof-of-concept experiments show that the sensor is capable of detecting pathogen concentration with down to a level of 105cfu/ml.
Focussed Ion Beam (FIB) machining has been demonstrated to be capable of fabricating nano and micro-structure elements. In this paper we demonstrate techniques to design and fabricate a 45° mirror on the end of both conventional single mode and multi-core fibres (MCF) using FIB processing. The mirror is finished by a two step process: first a scanning process is used to make a rough cut followed by a polishing process to create an optical surface finish. The machined 45° mirror can be accurately aligned with optical fibre core, which avoids issues associated with the alignment of external turning mirror components. Proof-of-concept tests demonstrate that the fabricated structure is capable of measuring two axis displacements interferometrically with a maximum displacement up to 1.0mm and an rms error of ~50nm.
There have been a number of papers focusing on fiber distributed sensing with coherent Rayleigh backscattering
published. However, up to now, very limited research articles on investigation of coherent Rayleigh backscattering signal
waveform and its physical mechanism have been reported. This paper first proposes a theoretical derivation to illustrate
coherent Rayleigh backscattering waveform. The theoretical model is then proved with numerical simulation and
experimental measurement. In addition, signal processing method is an important factor on the performance of a phasesensitive
OTDR system. An improvement of signal processing method, which is consisted of digital average, moving
average and interval subtraction, with good effect on locating external perturbation is also introduced.
Micro-cantilevers are one of the most popular Micro-Electronics-Mechanical-Sensor (MEMS).They've demonstrated in
a number of application areas such as chemical and bio-sensing. However, these devices usually need the alignment of
the cantilever with the read-out system, which can be challenging. Furthermore, it involves a bulky free-space optical
detection system. In this paper, we propose techniques to design and fabricate micro-cantilevers onto the end of standard single mode fibres using a picoseconds (ps) laser machining technique. In this way the cantilever can be aligned with the core of the fibre therefore offering stable and accurate means of optically addressing the cantilever. Low-cost optical sources and fibre coupled spectrometers are employed to interrogate the final cavity with a resolution around 15nm. Experiment show this optical fibre cantilever can be used as a displacement sensor with a dynamic range up to 7μm. Proof-of-concept experiments demonstrate that the cantilever could also be used as a temperature sensor in the range of 24-320°C with a temperature sensitivity of 0.5°C.
Micro-fabricated cantilevers have been reported recently as miniaturized, rapid response, ultrasensitive sensors elements
suitable for various chemical and bio-sensing applications. However, the alignment of the cantilever with the optical
read-out system can be challenging and typically involves a bulky free-space optical detection system. We propose using
cantilevers aligned to the core of an optical fibre during the fabrication process to address this issue.
Focussed Ion Beam (FIB) machining has been demonstrated as capable of fabricating fibre-top cantilevers. Here we
demonstrate techniques to design and fabricate micro-cantilevers using a combination of laser machining and FIB
processing to fabricate sensing cantilevers onto the end of standard and multi-core fibres (MCF). In this way the
cantilever can be aligned with the core of the fibre therefore offering stable and accurate means of optically addressing
the cantilever. Use of MCF offers the potential for a single probe capable of making multiple measurements in a
confined measurement volume, to determine multiple species of interest, or to provide background reference
measurements for example.
The optical cavity formed between the fibre and the cantilever is monitored using low-cost optical sources and fibre
coupled spectrometers to demonstrate a practical measurement system. This can readily achieve <50nm resolution using
analysis based upon recovering the free spectral range using the Fast Fourier Transform to calculate the final cavity