A deflection optical sensor based on a Scotch tape waveguide with an integrated grating coupler

•A waveguide cantilever with an integrated grating deflection sensor is proposed.•Cantilever deflection monitoring relies on a novel optical approach.•This approach is advantageous over an angle-dependent grating efficiency method. A deflection sensor based on a plastic waveguide cantilever is prese...

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Bibliographic Details
Published in:Sensors and actuators. A. Physical. 2018-01, Vol.269, p.500-504
Main Author: Barrios, Carlos Angulo
Format: Article
Language:English
Subjects:
Adhesive strength
Cables
Cantilever beams
Couplers
Deflection
Deflection sensor
Efficiency
Feasibility studies
Grating coupler
Incidence angle
Incident light
Interrogation
Noise
Optical measuring instruments
Optics
Photoelectric effect
Photoelectric emission
Polymer waveguide
Sensitivity
Sensitivity analysis
Sensors
Waveguide cantilever
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Summary:•A waveguide cantilever with an integrated grating deflection sensor is proposed.•Cantilever deflection monitoring relies on a novel optical approach.•This approach is advantageous over an angle-dependent grating efficiency method. A deflection sensor based on a plastic waveguide cantilever is presented and demonstrated. The waveguide cantilever is made of conventional adhesive tape and integrates a metal grating coupler at its deflecting end. Light impinging the grating is coupled into the tape waveguide and guided to a fixed photodetector on which the opposite end of the waveguide is anchored. The photodiode acts as the cantilever support and converts guided optical power into a photocurrent (sensor response). Deflection optical monitoring relies on the variation of the overlap of the incident light beam spot with the grating coupler as a function of the cantilever deflection. This approach leads to a larger deflection sensitivity than that obtained by a method based just on the variation of the grating coupling efficiency with the incidence angle. A 14.85-mm-long cantilever sensor has been fabricated and exhibits a linear working range of 2 decades with a maximum deflection sensitivity of 0.2 μA/μm and a resolution of 1.7 μm, limited by the interrogation light source noise. Noise analysis indicates the feasibility of sub-nanometric deflection resolution.
ISSN:0924-4247
1873-3069
DOI:10.1016/j.sna.2017.12.013