Microfiber Mach-Zehnder Interferometer Research Articles

Spectral characteristics of polymer micro-fiber MZI near 1550 nm

The authors have produced the polymer micro-fiber with a highly optical conductive efficiency of 83% and 89% for the pump light of 532nm and 1550nm, respectively. The authors constructed a Mach–Zehnder Interferometer (MZI) by a micro-manipulation method and measured the different interference spectra by micro-adjusting the path difference of the dual interference arms of MZI under a microscope. Due to the path difference, the coherent length of the corresponding spectrum continuously and slightly decreases from 20μm, 13.5μm, 10.6μm to 8μm. The relationships between this particular MZI structure and the surrounding temperature, as well as the refractive index changes can be determined via the evanescent field and the thermally induced expansion or contraction effect, which will be reflected in the interference spectrum.

Inline Microfiber Mach–Zehnder Interferometer for High Temperature Sensing

A compact inline microfiber Mach-Zehnder interferometer (MMZI) is proposed for high temperature sensing. The MMZI is fabricated using a flame-brushing technique in which both transition parts of a microfiber are tapered to reduce the waist diameter and form an interference region. Since the refractive index of the fiber core exhibits a different temperature coefficient from that of air, the interferometer is sensitive to temperature variation. The temperature sensitivity of the device with a length of 40 mm was measured to be 13.4 pm/ <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> C with an excellent linearity for temperature measurement up to 800 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> C.

Microfiber Mach-Zehnder interferometer based on long period grating for sensing applications

A Mach-Zehnder interferometer (MZI) composed by a pair of long period gratings (LPGs) fabricated in silica microfiber for sensing applications is demonstrated. Each LPG is fabricated with a pulsed CO2 laser by creating six periodical deformations along fiber length with only one scanning cycle. The length of the MZI can reach as short as 8.84 mm when the diameter of the microfiber is 9.5 μm. Compared with the ones fabricated in single-mode fibers, the present MZI is much shorter owing to the large effective-index difference between the fundamental and higher order modes. The microfiber MZI exhibits a sensitivity to surrounding refractive index (RI) of 2225 nm per refractive index unit and the temperature sensitivity of only 11.7 pm/°C. Theoretical analysis suggests that the performances of the MZI sensor can be improved by using thinner microfibers with a diameter down to 3.5 μm: The sensitivity can be greatly enhanced due to the stronger evanescent-field interaction and reduced dispersion factor; the transmission dips become narrower which benefits high-resolution measurement; the thinner fiber also allows further reduction in device length. The present device has great potential in biochemical and medical sensing due to the advantages including easy fabrication, excellent compactness and high sensitivity.

Current sensor based on inline microfiber Mach–Zehnder interferometer

A compact inline microfiber Mach–Zehnder interferometer (MMZI) is proposed for current sensor application. The MMZI is fabricated using flame-brushing technique where both transition parts of a microfiber are tapered to reduce the waist diameter and form an interference region. The fabricated MMZI shows a good interference fringes with a high extinction ratio of 15dB. The fringe spacing can be tuned from 3.95nm to 3.36nm as the length of the interference region is varied from 4.5mm to 6mm. The shift in the interference fringes is observed to be linearly proportional to the square of the amount of the flowing current and the slope efficiency of the sensor is obtained at 140.26pm/A2 with a correlation coefficient of 0.99. Since the refractive index of the fiber core has a different temperature coefficient than that of air, the interferometer can be used as a current sensor by placing the current carrying wire in contact with the waist region of the second part of the tapered fiber.

Demonstration of microfiber hybrid Mach–Zehnder and knot resonator structure

AbstractWe demonstrate a microfiber hybrid structure consisting of a microfiber knot resonator (MKR) and a microfiber Mach–Zehnder interferometer (MMZI) by micro‐manipulating a microfiber. The microfiber used has a waist diameter of 1 μm and is fabricated using a flame brush technique. The hybrid structure generates dual resonances spectrum, which combines a characteristic resonant of MKR and MMZI. The MMZI resonant exhibits a much higher free spectral range (FSR) of 3.1 nm with the extinction ratio of 3 dB. The MKR resonant has a FSR of 0.24 nm and extinction ratio of 5 dB. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:100–102, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27250

Tapered-fiber-based refractive index sensor at an air/solution interface

An approach to achieve refractive index sensing at an air and aqueous glycerol solution interface is proposed using a tapered-fiber-based microfiber Mach-Zehnder interferometer (MFMZI). Compared to a surrounding uniform medium of air or solutions, the spectral interference visibility of the MFMZI at the air/solution interface is significantly reduced due to a weak coupling between the fundamental cladding mode and high-order asymmetric cladding modes, which are extremely sensitive to the external refractive index. The MFMZI is experimentally demonstrated as an evanescent wave refractive index sensor to measure concentrations of glycerol solutions by monitoring average power attenuation of the tapered fiber.

Compact and Tunable Erbium-Doped Fiber Laser With Microfiber Mach–Zehnder Interferometer

A compact and tunable Erbium-doped fiber laser is demonstrated using a highly concentrated Erbium-doped fiber in conjunction with a microfiber Mach-Zehnder interferometer (MMZI) structure for the first time. A stable laser output is achieved at 1531.7 nm region with a peak power of -19 dBm and an optical signal to noise ratio of 30.1 dB using a 980-nm pump at 100 mW power. The operating wavelength of the laser can be tuned from 1530.2 to 1532.7 nm by changing the path length difference (PLD) inside the MMZI from 1.6 to 2.7 mm at room temperature. It is also observed that the operating wavelength linearly shifts to a longer wavelength as the PLD increases with a tuning slope efficiency of 0.17 nm/mm. The tuning ability is due to the alteration of the induced optical phase shift inside the MMZI which affects the optical interference and the dominant peak which is responsible for the lasing action.

Microfiber Mach-Zehnder interferometer embedded in low index polymer

Microfiber Mach Zehnder Interferometer (MMZI) is demonstrated by micromanipulating an optical microfiber drawn from a single mode fiber (SMF) using a flame brushing technique. The MMZI shows good interference fringes with an extinction ratio of 13 dB and a free spectral range (FSR) of 0.52 nm at 1530 nm. The MMZI is then embedded in a polymer with the refractive index of 1.36 to increase the stability and robustnes of the device. It is found that the transmission spectrum of the packaged MMZI is changed by the polymer, which increases the FSR to 0.83 nm. The degradation in transmission loss and extinction ratio are attributed to the disturbance at the coupling area during the packaging. Compared with waveguide based mach zehnder interferometer, the proposed MMZI is favoured due to easy fabrication, compact size, and easy integration with the fiber system.