High-Precision Interferometric Measurements of Gas Refractive Index Using Homodyne Detection

Balanced homodyne detection, which offers advantages that include low noise and strong anti-interference capabilities, is commonly used as a detection method in quantum metrology. In this article, we propose application of the balanced homodyne detection technique to the gas sensing and measurement...

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Main Authors: Yanan Miao, Fang Xie, Wentao Feng, Yifeng Zhu, Xun Zhang, Fang Liu
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Sensors
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Online Access:https://www.mdpi.com/1424-8220/25/11/3519
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author Yanan Miao
Fang Xie
Wentao Feng
Yifeng Zhu
Xun Zhang
Fang Liu
author_facet Yanan Miao
Fang Xie
Wentao Feng
Yifeng Zhu
Xun Zhang
Fang Liu
author_sort Yanan Miao
collection DOAJ
description Balanced homodyne detection, which offers advantages that include low noise and strong anti-interference capabilities, is commonly used as a detection method in quantum metrology. In this article, we propose application of the balanced homodyne detection technique to the gas sensing and measurement field. By constructing a Mach–Zehnder interferometer based on balanced homodyne detection, we realize high-precision measurement of the refractive index of air. The device exhibits interference efficiency of 99% and a common-mode rejection ratio of 40 dB, thus enabling dynamic monitoring of optical phase changes. Under conditions that include a stabilized temperature of 25 °C, atmospheric pressure of 100.08 kPa, and relative humidity of 30%, the refractive index of air was measured experimentally to be <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>n</mi><mo>=</mo><mn>1.0002711</mn></mrow></semantics></math></inline-formula> with a measured minimum standard deviation of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>7</mn></mrow></msup></mrow></semantics></math></inline-formula>. The proposed technique provides high measurement sensitivity and stability, and it also offers the advantage of noncontact measurement. Furthermore, the proposed scheme is applicable to both measurement and dynamic sensing of the refractive indices of gases, along with sensing and measurement of transparent liquids and biological samples.
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spelling doaj-art-4e5f7c94817e4d8d8a975b0cd7053aaf2025-08-20T02:23:00ZengMDPI AGSensors1424-82202025-06-012511351910.3390/s25113519High-Precision Interferometric Measurements of Gas Refractive Index Using Homodyne DetectionYanan Miao0Fang Xie1Wentao Feng2Yifeng Zhu3Xun Zhang4Fang Liu5Department of Physics, Nanjing Tech University, Nanjing 211816, ChinaDepartment of Physics, Nanjing Tech University, Nanjing 211816, ChinaDepartment of Physics, Nanjing Tech University, Nanjing 211816, ChinaDepartment of Physics, Nanjing Tech University, Nanjing 211816, ChinaDepartment of Physics, Nanjing Tech University, Nanjing 211816, ChinaDepartment of Physics, Nanjing Tech University, Nanjing 211816, ChinaBalanced homodyne detection, which offers advantages that include low noise and strong anti-interference capabilities, is commonly used as a detection method in quantum metrology. In this article, we propose application of the balanced homodyne detection technique to the gas sensing and measurement field. By constructing a Mach–Zehnder interferometer based on balanced homodyne detection, we realize high-precision measurement of the refractive index of air. The device exhibits interference efficiency of 99% and a common-mode rejection ratio of 40 dB, thus enabling dynamic monitoring of optical phase changes. Under conditions that include a stabilized temperature of 25 °C, atmospheric pressure of 100.08 kPa, and relative humidity of 30%, the refractive index of air was measured experimentally to be <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>n</mi><mo>=</mo><mn>1.0002711</mn></mrow></semantics></math></inline-formula> with a measured minimum standard deviation of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>7</mn></mrow></msup></mrow></semantics></math></inline-formula>. The proposed technique provides high measurement sensitivity and stability, and it also offers the advantage of noncontact measurement. Furthermore, the proposed scheme is applicable to both measurement and dynamic sensing of the refractive indices of gases, along with sensing and measurement of transparent liquids and biological samples.https://www.mdpi.com/1424-8220/25/11/3519homodyne detectionMach–Zehnder interferometrygas sensingair refractive index
spellingShingle Yanan Miao
Fang Xie
Wentao Feng
Yifeng Zhu
Xun Zhang
Fang Liu
High-Precision Interferometric Measurements of Gas Refractive Index Using Homodyne Detection
Sensors
homodyne detection
Mach–Zehnder interferometry
gas sensing
air refractive index
title High-Precision Interferometric Measurements of Gas Refractive Index Using Homodyne Detection
title_full High-Precision Interferometric Measurements of Gas Refractive Index Using Homodyne Detection
title_fullStr High-Precision Interferometric Measurements of Gas Refractive Index Using Homodyne Detection
title_full_unstemmed High-Precision Interferometric Measurements of Gas Refractive Index Using Homodyne Detection
title_short High-Precision Interferometric Measurements of Gas Refractive Index Using Homodyne Detection
title_sort high precision interferometric measurements of gas refractive index using homodyne detection
topic homodyne detection
Mach–Zehnder interferometry
gas sensing
air refractive index
url https://www.mdpi.com/1424-8220/25/11/3519
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