Ultra-Compact Mach–Zehnder Refractometer Based on Rice-Shaped Air Cavity Beam Expansion
This paper reports and demonstrates, for the first time, a Mach–Zehnder interferometer (MZI) sensor for refractive index (RI) detection based on a rice-shaped air cavity (RAC). In this design, RACs are inserted on both sides of a no-core fiber (NCF), functioning as a beam expander and receiver. When...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-06-01
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| Series: | Photonics |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2304-6732/12/6/602 |
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| Summary: | This paper reports and demonstrates, for the first time, a Mach–Zehnder interferometer (MZI) sensor for refractive index (RI) detection based on a rice-shaped air cavity (RAC). In this design, RACs are inserted on both sides of a no-core fiber (NCF), functioning as a beam expander and receiver. When the input light enters the NCF through the RAC, it is fully excited from the fundamental mode to higher-order modes within just 500 μm of propagation. This enables the sensor to achieve exceptionally high sensitivity in external RI detection. By adjusting the width of the RAC, the RI sensitivity can be effectively tuned. When the RAC measures 30.6 × 70 μm, the two selected transmission peaks reach maximum RI sensitivities of 1550.41 nm/RIU and 1810.89 nm/RIU, respectively. Notably, the total length of the sensor is only 0.64 mm, offering a promising approach for the development of ultra-compact RI sensors in the future. |
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| ISSN: | 2304-6732 |