Analytical and experimental study on a bent abrupt taper

Ghasemi, Pourya; Yam, S.S.-H.

doi:10.1364/oe.413139

Cited by 4 publications

(4 citation statements)

References 21 publications

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“…It is worth noting that in addition to the HE 11 and LP 11 modes, other higher-order modes such as HE 12 and HE 41 may also be excited by light propagating along the nonadiabatic downtaper. Among all the higher-order modes, LP 11 will be the most strongly excited, since the fiber sags during pulling [39]; this agrees with our beat length measurements shown in Table 1. Previously, it was shown that [6] by choosing a particular ratio of the resonator size to the diameter of the tapered fiber, only the HE 11 and LP 11 modes can significantly interact with the WGMs of a microresonator, and therefore, any weak excitation of other higher-order modes can be neglected.…”

Section: Fabrication Modeling and Testing Of Asymmetric Tapered Fibersupporting

confidence: 89%

Confirmation of Dissipative Sensing Enhancement in a Microresonator Using Multimode Input

Rajagopal,

Ke,

Sandoval

et al. 2023

Sensors

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Optical microresonators have proven to be especially useful for sensing applications. In most cases, the sensing mechanism is dispersive, where the resonance frequency of a mode shifts in response to a change in the ambient index of refraction. It is also possible to conduct dissipative sensing, in which absorption by an analyte causes measurable changes in the mode linewidth and in the throughput dip depth. If the mode is overcoupled, the dip depth response can be more sensitive than the linewidth response, but overcoupling is not always easy to achieve. We have recently shown theoretically that using multimode input to the microresonator can enhance the dip-depth sensitivity by a factor of several thousand relative to that of single-mode input and by a factor of nearly 100 compared to the linewidth sensitivity. Here, we experimentally confirm these enhancements using an absorbing dye dissolved in methanol inside a hollow bottle resonator. We review the theory, describe the setup and procedure, detail the fabrication and characterization of an asymmetrically tapered fiber to produce multimode input, and present sensing enhancement results that agree with all the predictions of the theory.

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Section: Fabrication Modeling and Testing Of Asymmetric Tapered Fibersupporting

confidence: 89%

Confirmation of Dissipative Sensing Enhancement in a Microresonator Using Multimode Input

Rajagopal,

Ke,

Sandoval

et al. 2023

Sensors

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show abstract

“…1(b), one of which is responsible for the higher-order modes (HOMs) excitation (the left taper), while the other taper acts as a phase-matching component to form interferometry between the HOMs and the fundamental mode. Based on the taper's geometry and the RI contrast of the SMF, the modes' excitation order and power evolution can be calculated using the CMT [11], [17]- [20]. The power evolution calculation provides us with a set of linearly polarized (LP) modes {Ψ ν }, their Effective Refractive Indices (ERIs) {n ν }, and complex amplitudes {A ν } along each taper; ν is the mode index.…”

Section: Theorymentioning

confidence: 99%

“…Amongst all, the latter in the form of a Double-Taper Mach-Zehnder Interferometer (DTMZI) shows more promise as it can be fabricated quickly with the essential tools in hand, namely single-mode fiber (SMF) and fusion splicer [8]. Moreover, abrupt taper's modeling and its fabrication imperfections have been thoroughly investigated via recent works [9]- [11]. The application of measuring axial strain has been studied on DTMZI, and their modal behaviour has been thoroughly studied [12], [13].…”

Section: Introductionmentioning

confidence: 99%

Tension and Torsion Sensing With a Double-Taper Mach-Zehnder Interferometer

Ghasemi

Yam

2022

J. Lightwave Technol.

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A novel setup for a Double-Taper Mach-Zehnder Interferometer (DTMZI) is presented to measure axial strain and torsion. An epoxy section is added between the two tapers as a fixture to ensure torsion sensing. The modal filtering effect of the epoxy upon the interferometry response is experimentally verified. The transmission spectrum of DTMZI under strain and torsion is modelled and further analyzed through the differential accumulated phase between the beating modes.The experimental spectral observation confirms our estimate. The relationships between the spectral shifts in wavelength and applied displacements are obtained. The sensor shows a very high sensitivity against the applied strain and twists.

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“…During the bending process of the LPFG, the mode field distribution of the core fundamental and cladding modes change, subsequently changing the coupling coefficient between them. In recent years, many optical fibre curvature sensors based on different optical devices have been proposed, such as LPFG [10][11][12][13][14][15], FBG [16,17], multi-core fibre [18,19], photonic crystal fibre [20,21] and fibre tapers [22] etc. In terms of curvature measurement of LPFG, Zhang et al [10] designed an arch-shaped LPFG that detects vector bending in two orthogonal directions.…”

Section: Introductionmentioning

confidence: 99%

Curvature prediction of long‐period fibre grating based on random forest regression

et al. 2022

IET Optoelectronics

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This study proposes a long‐period fibre grating (LPFG) curvature estimation method based on random forest regression (RFR) to address the shortcomings of the existing curvature evaluation method, namely, polynomial fitting; these shortcomings cause difficulty in achieving adequate model regularity and application universality. The resonant wavelength and resonant peak amplitude of the LPFG are used as input variables in this method to develop an RFR model for curvature estimation, allowing for accurate curvature prediction of the sample. The results show that the RFR‐based LPFG curvature prediction model can better characterise the input–output regression relationship than back‐propagation neural networks. The average R2 value of the RFR model is 0.9826, and the actual measured curvature value is highly correlated with the model predicted curvature value. Compared to that exhibited by back‐propagation neural networks, the RFR model exhibits higher accuracy for curvature estimation, with average values of 0.1314 and 0.1173 for root mean square and mean absolute errors, respectively. This method can provide a more comprehensive theoretical basis for the application of robot learning in the curvature measurement of LPFG and has practical value.

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Analytical and experimental study on a bent abrupt taper

Cited by 4 publications

References 21 publications

Confirmation of Dissipative Sensing Enhancement in a Microresonator Using Multimode Input

Confirmation of Dissipative Sensing Enhancement in a Microresonator Using Multimode Input

Tension and Torsion Sensing With a Double-Taper Mach-Zehnder Interferometer

Curvature prediction of long‐period fibre grating based on random forest regression

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