Miniaturized fiber inline Fabry-Perot interferometer fabricated with a femtosecond laser

Abstract

We report a miniaturized inline Fabry-Perot interferometer directly fabricated on a single-mode optical fiber with a femtosecond laser. The device had a loss of 16 dB and an interference visibility exceeding 14 dB. The device was tested and survived in high temperatures up to 1100 degrees C. With an accessible cavity and all-glass structure, the new device is attractive for sensing applications in high-temperature harsh environments.

Simultaneous measurement of temperature and refractive index using focused ion beam milled Fabry-Perot cavities in optical fiber micro-tips

“…Micromachining is a more recent technique that allows for the creation of very small cavities or microcavities. The two prominent techniques for optical fiber micromachining are femtosecond laser micromachining [11][12][13][14][15][16][17] and focused ion beam (FIB) milling [18][19][20][21][22][23]. Femtosecond (fs) laser micromachining has been used to create cavities in several ways.…”

“…Femtosecond (fs) laser micromachining has been used to create cavities in several ways. Wei et al used a fs-laser to mill an inline cavity and proposed it for temperature [11] and refractive index sensing [12]. Similarly, Ran et al have milled an air-gap and used fringe contrast to develop a temperature-insensitive refractive index sensor [13].…”

Note: Optical fiber milled by focused ion beam and its application for Fabry-Pérot refractive index sensor

“…The fiber constitutes the backbone conduit for light guiding, and effective light-fluid interaction is achieved when the microfluidic channel intersects the optical pathway. In recent years, devices such as microchannels, microslots, and FP interferometers have been fabricated in single-mode fibers (SMFs) by the use of femtosecond laser micromachining, [8][9][10][11][12] which can be effectively utilized for RI sensing with low temperature sensitivity and large dynamic range. However, a relative low fringe visibility of the interference pattern is achieved when using this technique for making FP fiber sensors.…”

“…[1][2][3][4][5][6][7][10][11][12] This improved fringe visibility is mainly due to the finely polished end facets and precisely milled parallel two end walls of the microcavity. A sensitivity of ∼1731 nm/RIU and a detection limit of ∼5.78 × 10 −6 RIU can be achieved, which is comparable to the FP sensitivity reported by other groups [1][2][3][4][5][6][7][10][11][12] and exceeds the 1500 nm/RIU demonstrated for long period grating based RI sensors in PCFs. 18 It is still a long way from the 70 000 nm/RIU predicted for two-core PCF coupler based RI sensors, 19,20 but the FP technology in standard SMF is more simple and robust.…”

Femtosecond laser fabricated micro Mach-Zehnder interferometer with Pd film as sensing materials for hydrogen sensing

“…Fs laser has been widely used for micromachining because of its good beam quality, high precision and excellent spatial resolution, which are particularly suitable for fabricating microcavity in the optical fiber. Various structures of microinterferometer cavity have been created by fs laser and used as optical fiber sensors [4][5][6][7][8]. Especially, an ultracompact microcavity Mach-Zehnder interferometer (MMZI) fabricated by fs laser has been used for measuring refractive index (RI) and different mixture ratios of N 2 and He gases [6,9].…”