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Malarich NA, Cossel KC, Deschenes JD, Giorgetta FR, Washburn BR, Newbury NR, Genest J, Coddington I. Removing biases in dual frequency comb spectroscopy due to digitizer nonlinearity. OPTICS EXPRESS 2023; 31:29074-29084. [PMID: 37710714 DOI: 10.1364/oe.497497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 07/31/2023] [Indexed: 09/16/2023]
Abstract
Operation of any dual-comb spectrometer requires digitization of the interference signal before further processing. Nonlinearities in the analog-to-digital conversion can alter the apparent gas concentration by multiple percent, limiting both precision and accuracy of this technique. This work describes both the measurement of digitizer nonlinearity and the development of a model that quantitatively describes observed concentration bias over a range of conditions. We present hardware methods to suppress digitizer-induced bias of concentration retrievals below 0.1%.
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Liu Z, Zhu L, Yan G. Fast gas sensing scheme with multi-component gas measurement capacity based on non-dispersive frequency comb spectroscopy (ND-FCS). OPTICS EXPRESS 2023; 31:8785-8796. [PMID: 36859986 DOI: 10.1364/oe.483084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Accepted: 02/07/2023] [Indexed: 06/18/2023]
Abstract
A fast gas sensing scheme based on a non-dispersive frequency comb spectroscopy (ND-FCS) is proposed and experimentally demonstrated. Its capacity for multi-component gas measurement is experimentally investigated as well, by using the time-division-multiplexing (TDM) method to realize specific wavelength selection of the fiber laser optical frequency comb (OFC). A dual-channel optical fiber sensing scheme is established with a sensing path consisting of a multi-pass gas cell (MPGC), and a reference path with a calibrated signal to track the repetition frequency drift of the OFC for a real-time lock-in compensation and system stabilization. The long-term stability evaluation and the simultaneous dynamic monitoring are carried out, with the target gases of ammonia (NH3), carbon monoxide (CO) and carbon dioxide (CO2). The fast CO2 detection in human breath is also conducted. The experimental results show that at an integration time of 10 ms, the detection limits of the three species are evaluated to be 0.0048%, 0.1869% and 0.0467%, respectively. A low minimum detectable absorbance (MDA) down to 2.8 × 10-4 can be achieved and a dynamic response with millisecond time can be realized. Our proposed ND-FCS exhibits excellent gas sensing performance with merits of high sensitivity, fast response and long-term stability. It also shows great potential for multi-component gas monitoring in atmospheric monitoring applications.
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Kim SJ, Choi MS, Lee SH, Jeong WN, Lee YS, Seong IH, Cho CH, Kim DW, You SJ. Development of the Tele-Measurement of Plasma Uniformity via Surface Wave Information (TUSI) Probe for Non-Invasive In-Situ Monitoring of Electron Density Uniformity in Plasma Display Fabrication Process. SENSORS (BASEL, SWITZERLAND) 2023; 23:s23052521. [PMID: 36904724 PMCID: PMC10006970 DOI: 10.3390/s23052521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/20/2023] [Accepted: 02/21/2023] [Indexed: 05/14/2023]
Abstract
The importance of monitoring the electron density uniformity of plasma has attracted significant attention in material processing, with the goal of improving production yield. This paper presents a non-invasive microwave probe for in-situ monitoring electron density uniformity, called the Tele-measurement of plasma Uniformity via Surface wave Information (TUSI) probe. The TUSI probe consists of eight non-invasive antennae and each antenna estimates electron density above the antenna by measuring the surface wave resonance frequency in a reflection microwave frequency spectrum (S11). The estimated densities provide electron density uniformity. For demonstration, we compared it with the precise microwave probe and results revealed that the TUSI probe can monitor plasma uniformity. Furthermore, we demonstrated the operation of the TUSI probe beneath a quartz or wafer. In conclusion, the demonstration results indicated that the TUSI probe can be used as an instrument for a non-invasive in-situ method for measuring electron density uniformity.
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Affiliation(s)
- Si-Jun Kim
- Applied Physics Lab for PLasma Engineering (APPLE), Department of Physics, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Min-Su Choi
- Applied Physics Lab for PLasma Engineering (APPLE), Department of Physics, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Sang-Ho Lee
- Department of Plasma Engineering, Korea Institute of Machinery and Materials (KIMM), Daejeon 34104, Republic of Korea
| | - Won-Nyoung Jeong
- Applied Physics Lab for PLasma Engineering (APPLE), Department of Physics, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Young-Seok Lee
- Applied Physics Lab for PLasma Engineering (APPLE), Department of Physics, Chungnam National University, Daejeon 34134, Republic of Korea
| | - In-Ho Seong
- Applied Physics Lab for PLasma Engineering (APPLE), Department of Physics, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Chul-Hee Cho
- Applied Physics Lab for PLasma Engineering (APPLE), Department of Physics, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Dae-Woong Kim
- Department of Plasma Engineering, Korea Institute of Machinery and Materials (KIMM), Daejeon 34104, Republic of Korea
| | - Shin-Jae You
- Applied Physics Lab for PLasma Engineering (APPLE), Department of Physics, Chungnam National University, Daejeon 34134, Republic of Korea
- Institute of Quantum Systems (IQS), Chungnam National University, Daejeon 34134, Republic of Korea
- Correspondence:
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Kim SJ, Lee SH, You YB, Lee YS, Seong IH, Cho CH, Lee JJ, You SJ. Development of the Measurement of Lateral Electron Density (MOLE) Probe Applicable to Low-Pressure Plasma Diagnostics. SENSORS (BASEL, SWITZERLAND) 2022; 22:s22155487. [PMID: 35897990 PMCID: PMC9331997 DOI: 10.3390/s22155487] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 07/16/2022] [Accepted: 07/18/2022] [Indexed: 05/27/2023]
Abstract
As the importance of measuring electron density has become more significant in the material fabrication industry, various related plasma monitoring tools have been introduced. In this paper, the development of a microwave probe, called the measurement of lateral electron density (MOLE) probe, is reported. The basic properties of the MOLE probe are analyzed via three-dimensional electromagnetic wave simulation, with simulation results showing that the probe estimates electron density by measuring the surface wave resonance frequency from the reflection microwave frequency spectrum (S11). Furthermore, an experimental demonstration on a chamber wall measuring lateral electron density is conducted by comparing the developed probe with the cutoff probe, a precise electron density measurement tool. Based on both simulation and experiment results, the MOLE probe is shown to be a useful instrument to monitor lateral electron density.
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Affiliation(s)
- Si-jun Kim
- Applied Physics Lab for PLasma Engineering (APPLE), Department of Physics, Chungnam National University, Daejeon 34134, South Korea; (S.-j.K.); (S.-h.L.); (Y.-b.Y.); (Y.-s.L.); (I.-h.S.); (C.-h.C.)
| | - Sang-ho Lee
- Applied Physics Lab for PLasma Engineering (APPLE), Department of Physics, Chungnam National University, Daejeon 34134, South Korea; (S.-j.K.); (S.-h.L.); (Y.-b.Y.); (Y.-s.L.); (I.-h.S.); (C.-h.C.)
- Department of Plasma Engineering, Korea Institute of Machinery and Materials (KIMM), Daejeon 34104, South Korea
| | - Ye-bin You
- Applied Physics Lab for PLasma Engineering (APPLE), Department of Physics, Chungnam National University, Daejeon 34134, South Korea; (S.-j.K.); (S.-h.L.); (Y.-b.Y.); (Y.-s.L.); (I.-h.S.); (C.-h.C.)
| | - Young-seok Lee
- Applied Physics Lab for PLasma Engineering (APPLE), Department of Physics, Chungnam National University, Daejeon 34134, South Korea; (S.-j.K.); (S.-h.L.); (Y.-b.Y.); (Y.-s.L.); (I.-h.S.); (C.-h.C.)
| | - In-ho Seong
- Applied Physics Lab for PLasma Engineering (APPLE), Department of Physics, Chungnam National University, Daejeon 34134, South Korea; (S.-j.K.); (S.-h.L.); (Y.-b.Y.); (Y.-s.L.); (I.-h.S.); (C.-h.C.)
| | - Chul-hee Cho
- Applied Physics Lab for PLasma Engineering (APPLE), Department of Physics, Chungnam National University, Daejeon 34134, South Korea; (S.-j.K.); (S.-h.L.); (Y.-b.Y.); (Y.-s.L.); (I.-h.S.); (C.-h.C.)
| | - Jang-jae Lee
- Samsung Electronics, Hwaseong-si 18448, South Korea;
| | - Shin-jae You
- Applied Physics Lab for PLasma Engineering (APPLE), Department of Physics, Chungnam National University, Daejeon 34134, South Korea; (S.-j.K.); (S.-h.L.); (Y.-b.Y.); (Y.-s.L.); (I.-h.S.); (C.-h.C.)
- Institute of Quantum Systems (IQS), Chungnam National University, Daejeon 34134, South Korea
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Mid-infrared supercontinuum-based Fourier transform spectroscopy for plasma analysis. Sci Rep 2022; 12:9642. [PMID: 35688925 PMCID: PMC9187747 DOI: 10.1038/s41598-022-13787-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 05/27/2022] [Indexed: 11/21/2022] Open
Abstract
Broadband mid-infrared (MIR) spectroscopy is a well-established and valuable diagnostic technique for reactive plasmas. Plasmas are complex systems and consist of numerous (reactive) types of molecules; it is challenging to measure and control reaction specificity with a good sensitivity. Here, we demonstrate the first use of a novel MIR supercontinuum (SC) source for quantitative plasma spectroscopy. The SC source has a wide spectral coverage of 1300–2700 cm−1 (wavelength range 3.7–7.7 μm), thus enabling broadband multispecies detection. The high spatial coherence of the MIR SC source provides long interaction path lengths, thereby increasing the sensitivity for molecular species. The combination of such a SC source with a custom-built FTIR spectrometer (0.1 cm−1 spectral resolution) allows detection of various gases with high spectral resolution. We demonstrate its potential in plasma applications by accurate identification and quantification of a variety of reaction products (e.g. nitrogen oxides and carbon oxides) under low-pressure conditions, including the molecular species with overlapping absorbance features (e.g. acetone, acetaldehyde, formaldehyde, etc.).
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Gianella M, Vogel S, Wittwer VJ, Südmeyer T, Faist J, Emmenegger L. Frequency axis for swept dual-comb spectroscopy with quantum cascade lasers. OPTICS LETTERS 2022; 47:625-628. [PMID: 35103695 DOI: 10.1364/ol.446347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 12/20/2021] [Indexed: 06/14/2023]
Abstract
In dual-comb spectroscopy, there is a one-to-one map between the frequencies of the measured beat notes and the frequencies of the optical comb lines. Its determination usually involves the use of one or more reference lasers with known frequencies. Quantum cascade laser frequency combs, however, are often operated in a free-running mode, and without a reference, the determination of the RF-to-optical frequency map is not trivial. Here, we propose a method by which the comb shift is measured with an unbalanced Mach-Zehnder interferometer, and the spectral point spacing is determined through the intermode beat measured on the laser electrodes. The frequency axis is accurate within ∼ 0.001 cm-1.
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