Confirmation of Dissipative Sensing Enhancement in a Microresonator Using Multimode Input

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...

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Main Authors: Sreekul Raj Rajagopal, Limu Ke, Karleyda Sandoval, Albert T. Rosenberger
Format: Article
Language:English
Published: MDPI AG 2023-10-01
Series:Sensors
Subjects:
Online Access:https://www.mdpi.com/1424-8220/23/21/8700
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author Sreekul Raj Rajagopal
Limu Ke
Karleyda Sandoval
Albert T. Rosenberger
author_facet Sreekul Raj Rajagopal
Limu Ke
Karleyda Sandoval
Albert T. Rosenberger
author_sort Sreekul Raj Rajagopal
collection DOAJ
description 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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spelling doaj.art-6f86cfd15dcc487fa2b39285a9b0fe4c2023-11-10T15:11:45ZengMDPI AGSensors1424-82202023-10-012321870010.3390/s23218700Confirmation of Dissipative Sensing Enhancement in a Microresonator Using Multimode InputSreekul Raj Rajagopal0Limu Ke1Karleyda Sandoval2Albert T. Rosenberger3Department of Physics, Oklahoma State University, Stillwater, OK 74078, USADepartment of Physics, Oklahoma State University, Stillwater, OK 74078, USADepartment of Physics, Oklahoma State University, Stillwater, OK 74078, USADepartment of Physics, Oklahoma State University, Stillwater, OK 74078, USAOptical 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.https://www.mdpi.com/1424-8220/23/21/8700microresonatorwhispering-gallery modesdissipative sensingmultimode fiber
spellingShingle Sreekul Raj Rajagopal
Limu Ke
Karleyda Sandoval
Albert T. Rosenberger
Confirmation of Dissipative Sensing Enhancement in a Microresonator Using Multimode Input
Sensors
microresonator
whispering-gallery modes
dissipative sensing
multimode fiber
title Confirmation of Dissipative Sensing Enhancement in a Microresonator Using Multimode Input
title_full Confirmation of Dissipative Sensing Enhancement in a Microresonator Using Multimode Input
title_fullStr Confirmation of Dissipative Sensing Enhancement in a Microresonator Using Multimode Input
title_full_unstemmed Confirmation of Dissipative Sensing Enhancement in a Microresonator Using Multimode Input
title_short Confirmation of Dissipative Sensing Enhancement in a Microresonator Using Multimode Input
title_sort confirmation of dissipative sensing enhancement in a microresonator using multimode input
topic microresonator
whispering-gallery modes
dissipative sensing
multimode fiber
url https://www.mdpi.com/1424-8220/23/21/8700
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AT karleydasandoval confirmationofdissipativesensingenhancementinamicroresonatorusingmultimodeinput
AT alberttrosenberger confirmationofdissipativesensingenhancementinamicroresonatorusingmultimodeinput