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Optical Imaging, Optical Sensing and Devices

A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Optical Sensors".

Deadline for manuscript submissions: closed (30 April 2022) | Viewed by 28865

Special Issue Editors

Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Hong Kong, China
Interests: optical encoding; information photonics; free-space optical transmission; optical imaging/sensing; single-pixel imaging; digital holography; information optics; optical signal/image processing; deep learning in optics and photonics
Special Issues, Collections and Topics in MDPI journals
School of Optics and Electronic Information & Wuhan National Lab for Optoelectronics (WNLO), Huazhong University of Science and Technology, Wuhan 430074, China
Interests: optical fiber sensors; optical fiber communication; OFDM modulation; optical fiber networks; diffraction gratings; distributed sensors; optical fiber fabrication
School of Optics and Electronic Information & Wuhan National Lab for Optoelectronics (WNLO), Huazhong University of Science and Technology, Wuhan 430074, China
Interests: distributed fiber-optic sensor systems; machine learning/image processing techniques for fiber sensing systems; optical signal processing; digital signal processing; fiber devices; nonlinear fiber optics

Special Issue Information

Dear Colleagues,

This Special Issue will highlight the latest research advances in optical imaging, optical sensing and devices, emphasizing the integration of opto-electric measurement and computational processing; theoretical to experimental demonstration; and various applications of the latest advances in optical imaging, optical sensing and devices.

This Special Issue will bring together contributions by outstanding international leaders, researchers, scientists and engineers from a broad range of interdisciplinary fields to present their work in the science, technology and applications of optical imaging, optical sensing and devices.

This Special Issue will focus on the current state-of-the-art of optical imaging, sensing and devices, covering recent technological developments in new imaging and sensing principles and systems and the emerging applications. Original research papers and review articles describing the current state-of-the-art in this research field are welcome.

The manuscripts should cover, but are not limited to, the following topics:

  • Physical, chemical, and environmental optical sensors;
  • Nano- and micro-structured fiber sensors;
  • Advances in optical sensing techniques;
  • Intelligent structures for optical sensors;
  • Optical fibers for imaging and sensing;
  • Diffraction gratings and distributed fiber sensors;
  • Optical fiber fabrication;
  • Integrated sensing and calculation networks;
  • Digital holography for optical imaging and sensing;
  • Single-pixel (or ghost) imaging;
  • Non-line-of-sight imaging;
  • Quantum imaging;
  • Computational imaging;
  • Defense and security with optical imaging and sensing;
  • Optical engineering design of 3D information acquisition;
  • Optical signal processing for imaging and sensing;
  • Deep learning for optical imaging, sensing and devices

Prof. Dr. Wen Chen
Prof. Dr. Ming Tang
Prof. Dr. Liang Wang
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • optical imaging
  • optical sensing
  • optical devices
  • optical measurements
  • optical fiber

Published Papers (13 papers)

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Editorial

Jump to: Research, Review

3 pages, 152 KiB  
Editorial
Optical Imaging, Optical Sensing and Devices
by Wen Chen, Ming Tang and Liang Wang
Sensors 2023, 23(6), 2882; https://0-doi-org.brum.beds.ac.uk/10.3390/s23062882 - 07 Mar 2023
Cited by 1 | Viewed by 1363
Abstract
Technological advances have recently provided an excellent opportunity for development in optical fields, e [...] Full article
(This article belongs to the Special Issue Optical Imaging, Optical Sensing and Devices)

Research

Jump to: Editorial, Review

8 pages, 2020 KiB  
Communication
Raman Scattering Study of Amino Acids Adsorbed on a Silver Nanoisland Film
by Alexey Skvortsov, Ekaterina Babich, Andrey Lipovskii, Alexey Redkov, Guang Yang and Valentina Zhurikhina
Sensors 2022, 22(14), 5455; https://0-doi-org.brum.beds.ac.uk/10.3390/s22145455 - 21 Jul 2022
Cited by 4 | Viewed by 1667
Abstract
We studied the surface-enhanced Raman spectra of amino acids D-alanine and DL-serine and their mixture on silver nanoisland films (SNF) immersed in phosphate-buffered saline (PBS) solution at millimolar amino acid concentrations. It is shown that the spectra from the amino acid [...] Read more.
We studied the surface-enhanced Raman spectra of amino acids D-alanine and DL-serine and their mixture on silver nanoisland films (SNF) immersed in phosphate-buffered saline (PBS) solution at millimolar amino acid concentrations. It is shown that the spectra from the amino acid solutions differ from the reference spectra for microcrystallites due to the electrostatic orientation of amino acid zwitterions by the metal nanoisland film. Moreover, non-additive peaks are observed in the spectrum of the mixture of amino acids adsorbed on SNF, which means that intermolecular interactions between adsorbed amino acids are very significant. The results indicate the need for a thorough analysis of the Raman spectra from amino acid solutions, particularly, in PBS, in the presence of a nanostructured silver surface, and may also be of interest for studying molecular properties and intermolecular interactions. Full article
(This article belongs to the Special Issue Optical Imaging, Optical Sensing and Devices)
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16 pages, 8127 KiB  
Communication
Precision Measurement Method of Large Shaft Diameter Based on Dual Camera System
by Xianyou Li, Ke Xu and Shun Wang
Sensors 2022, 22(11), 3982; https://0-doi-org.brum.beds.ac.uk/10.3390/s22113982 - 24 May 2022
Cited by 4 | Viewed by 1795
Abstract
At present, there is a problem that the measurement accuracy and measurement range cannot be balanced in the measurement of shaft diameter by the machine vision method. In this paper, we propose a large-scale shaft diameter precision measurement method based on a dual [...] Read more.
At present, there is a problem that the measurement accuracy and measurement range cannot be balanced in the measurement of shaft diameter by the machine vision method. In this paper, we propose a large-scale shaft diameter precision measurement method based on a dual camera measurement system. The unified world coordinate system of the two cameras is established by analyzing the dual camera imaging model and obtaining the measurement formula. In order to verify the validity of the proposed method, two black blocks in the calibration plate with a known center distance of 100 mm were measured. The mean value was 100.001 mm and the standard deviation was 0.00039 in 10 measurements. Finally, the proposed system was applied to the diameter measurement of a complexed crankshaft. The mean μ95 values of CMM and the proposed method were ±1.02 μm and ±1.07 μm, respectively, indicating that the measurement accuracy of the proposed method is roughly equal to the CMM. Full article
(This article belongs to the Special Issue Optical Imaging, Optical Sensing and Devices)
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12 pages, 3910 KiB  
Article
Temperature-Compensated Multi-Point Strain Sensing Based on Cascaded FBG and Optical FMCW Interferometry
by Zhiyu Feng, Yu Cheng, Ming Chen, Libo Yuan, Deng Hong and Litong Li
Sensors 2022, 22(11), 3970; https://0-doi-org.brum.beds.ac.uk/10.3390/s22113970 - 24 May 2022
Cited by 8 | Viewed by 1646
Abstract
We proposed a novel temperature-compensated multi-point strain sensing system based on cascaded FBG and optical FMCW interferometry. The former is used for simultaneous sensing of temperature and strain, and the latter is used for position information reading and multiplexing. In the experiment, a [...] Read more.
We proposed a novel temperature-compensated multi-point strain sensing system based on cascaded FBG and optical FMCW interferometry. The former is used for simultaneous sensing of temperature and strain, and the latter is used for position information reading and multiplexing. In the experiment, a narrow linewidth laser with continuous frequency-sweeping was used as the light source. After demodulating the beat-frequency signal, the link information of the 16 m fiber was obtained, and the measured result was identical to the actual position. The measurement accuracy reached 50.15 mm, and the dynamic range was up to 22.68 dB. Meanwhile, we completed the sensing experiments for temperature range from 20 °C to 90 °C and strain range from 0 με to 7000 με. The sensitivity of the sensing system to temperature was 10.21 pm/°C, the sensitivity and accuracy to strain were as high as 1.163 pm/με and 10 με, respectively. Finally, the measured strain and temperature values were obtained using the sensing matrix. The sensing system has important practical significance in the field of quasi-distributed strain measurement. Full article
(This article belongs to the Special Issue Optical Imaging, Optical Sensing and Devices)
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18 pages, 41479 KiB  
Article
Simulation and Experimental Research on a Beam Homogenization System of a Semiconductor Laser
by Haijing Zheng, Huayan Sun, Huaili Zhang, Yingchun Li, Huichao Guo, Laixian Zhang, Rong Li and Qiang Yin
Sensors 2022, 22(10), 3725; https://0-doi-org.brum.beds.ac.uk/10.3390/s22103725 - 13 May 2022
Cited by 2 | Viewed by 1885
Abstract
Aiming at the application of laser active imaging detection technology, this paper studied the beam homogenization system of a semiconductor laser based on a homogenizing pipe. Firstly, the principle of the homogenizing pipe was introduced. Secondly, the homogenization effect, which was influenced by [...] Read more.
Aiming at the application of laser active imaging detection technology, this paper studied the beam homogenization system of a semiconductor laser based on a homogenizing pipe. Firstly, the principle of the homogenizing pipe was introduced. Secondly, the homogenization effect, which was influenced by several geometric parameters (aperture size, length, and taper) of the homogenizing pipe using the optical design software, was simulated for the fiber-coupled semiconductor laser. Finally, according to the simulated results, a laser illumination system composed of a fiber-coupled semiconductor laser, a homogenizing pipe, and an aspheric lens was designed, which can obtain a rectangular uniform light spot in a long distance. The effectiveness of the illumination system was verified by simulation and experiment, respectively. Simulation results suggested that the uniformity of the spot at a distance of 20 m was 85.6%, while divergence angle was 10 mrad. The uniformity of the spot at a distance of 120 m was 91.5%, while divergence angle was 10 mrad. Experimental results showed that the uniformity of the spot at a distance of 20 m was 87.7%, while divergence angle was 13 mrad. The uniformity of the spot at a distance of 120 m was 93.3%, while divergence angle was 15 mrad. The laser illumination system designed in this paper was simple and easy to assemble, and has strong practicability. The results in this paper have certain reference value and guiding significance for the homogenization design of semiconductor lasers. Full article
(This article belongs to the Special Issue Optical Imaging, Optical Sensing and Devices)
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12 pages, 4393 KiB  
Article
Time-of-Flight Imaging in Fog Using Polarization Phasor Imaging
by Yixin Zhang, Xia Wang, Yuwei Zhao and Yujie Fang
Sensors 2022, 22(9), 3159; https://0-doi-org.brum.beds.ac.uk/10.3390/s22093159 - 20 Apr 2022
Cited by 5 | Viewed by 2126
Abstract
Due to the light scattered by atmospheric aerosols, the amplitude image contrast is degraded and the depth measurement is greatly distorted for time-of-flight (ToF) imaging in fog. The problem limits ToF imaging to be applied in outdoor settings, such as autonomous driving. To [...] Read more.
Due to the light scattered by atmospheric aerosols, the amplitude image contrast is degraded and the depth measurement is greatly distorted for time-of-flight (ToF) imaging in fog. The problem limits ToF imaging to be applied in outdoor settings, such as autonomous driving. To improve the quality of the images captured by ToF cameras, we propose a polarization phasor imaging method for image recovery in foggy scenes. In this paper, optical polarimetric defogging is introduced into ToF phasor imaging, and the degree of polarization phasor is proposed to estimate the scattering component. A polarization phasor imaging model is established, aiming at separating the target component from the signal received by ToF cameras to recover the amplitude and depth information. The effectiveness of this method is confirmed by several experiments with artificial fog, and the experimental results demonstrate that the proposed method significantly improves the image quality, with robustness in different thicknesses of fog. Full article
(This article belongs to the Special Issue Optical Imaging, Optical Sensing and Devices)
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11 pages, 4663 KiB  
Communication
Dual-Wavelength Polarization-Dependent Bifocal Metalens for Achromatic Optical Imaging Based on Holographic Principle
by Jiaqi Qu, Huaijian Luo and Changyuan Yu
Sensors 2022, 22(5), 1889; https://0-doi-org.brum.beds.ac.uk/10.3390/s22051889 - 28 Feb 2022
Cited by 3 | Viewed by 2187
Abstract
Recently, ultrathin metalenses have attracted dramatically growing interest in optical imaging systems due to the flexible control of light at the nanoscale. In this paper, we propose a dual-wavelength achromatic metalens that will generate one or two foci according to the polarization of [...] Read more.
Recently, ultrathin metalenses have attracted dramatically growing interest in optical imaging systems due to the flexible control of light at the nanoscale. In this paper, we propose a dual-wavelength achromatic metalens that will generate one or two foci according to the polarization of the incident. Based on geometric phase modulation, two unit cells are attentively selected for efficient operation at distinct wavelengths. By patterning them to two divided sections of the metalens structure plane, the dual-wavelength achromatic focusing effect with the same focal length is realized. In addition, the holographic concept is adopted for polarization-dependent bifocal generation, in which the objective wave is originated from two foci that are respectively formed by two orthogonal polarization states of circularly polarized light, namely Left-handed circularly polarized (LCP) light and Right-handed circularly polarized (RCP) light. The incident light is considered as the reference light. The achromatic focusing and polarization-dependent bifocusing are numerically verified through simulations. The proposed design opens the path for the combination of multi-wavelength imaging and chiral imaging, which may find potential applications, such as achromatic optical devices and polarization-controlled biomedical molecular imaging systems. Full article
(This article belongs to the Special Issue Optical Imaging, Optical Sensing and Devices)
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13 pages, 4810 KiB  
Article
Few-Mode Fiber Characterization System Based on the Spatially and Spectrally Imaging Technique
by Jianxun Yu, Fengze Tan and Changyuan Yu
Sensors 2022, 22(5), 1809; https://0-doi-org.brum.beds.ac.uk/10.3390/s22051809 - 25 Feb 2022
Cited by 2 | Viewed by 1555
Abstract
With the widespread use of few-mode fibers, mode characteristics testing becomes essential. In this paper, current few-mode fiber testing techniques are discussed, and the S2 imaging technique is chosen and demonstrated to be capable of few-mode fiber characterization in principle. As a [...] Read more.
With the widespread use of few-mode fibers, mode characteristics testing becomes essential. In this paper, current few-mode fiber testing techniques are discussed, and the S2 imaging technique is chosen and demonstrated to be capable of few-mode fiber characterization in principle. As a result, the few-mode fiber characterization system with the S2 imaging technique is built and used to obtain accurate mode dispersion of two-mode fibers (a commonly used few-mode fiber) of different lengths. Then, various filters are applied to extract the fundamental and high-order modes to acquire mode coupling components (discrete and distributed mode coupling). The proposed system spectrally characterizes the few-mode fiber by resolving the interference information from the superimposed optical field spatially and has a simple structure and easy operation, which will provide parameter guidance for FMF designing and the FMF sensing experiment optimizing. Full article
(This article belongs to the Special Issue Optical Imaging, Optical Sensing and Devices)
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13 pages, 3599 KiB  
Article
An Optical Fiber Sensor for Axial Strain, Curvature, and Temperature Measurement Based on Single-Core Six-Hole Optical Fiber
by Yujian Li, Changyuan Yu and Ping Lu
Sensors 2022, 22(4), 1666; https://0-doi-org.brum.beds.ac.uk/10.3390/s22041666 - 21 Feb 2022
Cited by 9 | Viewed by 2146
Abstract
In this paper, the field distribution and effective refractive index of transmission modes in single-core six-hole optical fiber were researched by modeling and simulation experiments. Based on the simulation results, a new type of sensor for axial strain, curvature, and temperature applications measurement [...] Read more.
In this paper, the field distribution and effective refractive index of transmission modes in single-core six-hole optical fiber were researched by modeling and simulation experiments. Based on the simulation results, a new type of sensor for axial strain, curvature, and temperature applications measurement was designed and fabricated. The experimental results showed that the axial strain sensitivities at different dips were −0.97 pm/με and −1.05 pm/με in the range from 0 to 2000 με, and the temperature sensitivities were 35.17 pm/°C and 47.27 pm/°C in the range from 25 to 75 °C. In addition, the proposed sensor also detected the curvature change with sensitivities of 7.36 dB/m1 and 20.08 dB/m−1 from −2.582 m−1 to −1.826 m−1, respectively. Finally, through theoretical analysis, it can be deduced that this has potential application in the field of simultaneous measurement of strain and temperature. Full article
(This article belongs to the Special Issue Optical Imaging, Optical Sensing and Devices)
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12 pages, 4203 KiB  
Article
Three-Dimensional Reconstruction of Light Field Based on Phase Similarity
by Wei Feng, Junhui Gao, Tong Qu, Shiqi Zhou and Daxing Zhao
Sensors 2021, 21(22), 7734; https://0-doi-org.brum.beds.ac.uk/10.3390/s21227734 - 20 Nov 2021
Cited by 4 | Viewed by 2265
Abstract
Light field imaging plays an increasingly important role in the field of three-dimensional (3D) reconstruction because of its ability to quickly obtain four-dimensional information (angle and space) of the scene. In this paper, a 3D reconstruction method of light field based on phase [...] Read more.
Light field imaging plays an increasingly important role in the field of three-dimensional (3D) reconstruction because of its ability to quickly obtain four-dimensional information (angle and space) of the scene. In this paper, a 3D reconstruction method of light field based on phase similarity is proposed to increase the accuracy of depth estimation and the scope of applicability of epipolar plane image (EPI). The calibration method of the light field camera was used to obtain the relationship between disparity and depth, and the projector calibration was removed to make the experimental procedure more flexible. Then, the disparity estimation algorithm based on phase similarity was designed to effectively improve the reliability and accuracy of disparity calculation, in which the phase information was used instead of the structure tensor, and the morphological processing method was used to denoise and optimize the disparity map. Finally, 3D reconstruction of the light field was realized by combining disparity information with the calibrated relationship. The experimental results showed that the reconstruction standard deviation of the two objects was 0.3179 mm and 0.3865 mm compared with the ground truth of the measured objects, respectively. Compared with the traditional EPI method, our method can not only make EPI perform well in a single scene or blurred texture situations but also maintain good reconstruction accuracy. Full article
(This article belongs to the Special Issue Optical Imaging, Optical Sensing and Devices)
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9 pages, 1735 KiB  
Communication
Locking Multi-Laser Frequencies to a Precision Wavelength Meter: Application to Cold Atoms
by Junwoo Kim, Keumhyun Kim, Dowon Lee, Yongha Shin, Sungsam Kang, Jung-Ryul Kim, Youngwoon Choi, Kyungwon An and Moonjoo Lee
Sensors 2021, 21(18), 6255; https://0-doi-org.brum.beds.ac.uk/10.3390/s21186255 - 18 Sep 2021
Cited by 5 | Viewed by 2903
Abstract
We herein report a simultaneous frequency stabilization of two 780-nm external cavity diode lasers using a precision wavelength meter (WLM). The laser lock performance is characterized by the Allan deviation measurement in which we find σy=1012 at an [...] Read more.
We herein report a simultaneous frequency stabilization of two 780-nm external cavity diode lasers using a precision wavelength meter (WLM). The laser lock performance is characterized by the Allan deviation measurement in which we find σy=1012 at an averaging time of 1000 s. We also obtain spectral profiles through a heterodyne spectroscopy, identifying the contribution of white and flicker noises to the laser linewidth. The frequency drift of the WLM is measured to be about 2.0(4) MHz over 36 h. Utilizing the two lasers as a cooling and repumping field, we demonstrate a magneto-optical trap of 87Rb atoms near a high-finesse optical cavity. Our laser stabilization technique operates at broad wavelength range without a radio frequency element. Full article
(This article belongs to the Special Issue Optical Imaging, Optical Sensing and Devices)
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16 pages, 8790 KiB  
Article
A Multi-Image Encryption Based on Sinusoidal Coding Frequency Multiplexing and Deep Learning
by Qi Li, Xiangfeng Meng, Yongkai Yin and Huazheng Wu
Sensors 2021, 21(18), 6178; https://0-doi-org.brum.beds.ac.uk/10.3390/s21186178 - 15 Sep 2021
Cited by 6 | Viewed by 2214
Abstract
Multi-image encryption technology is a vital branch of optical encryption technology. The traditional encryption method can only encrypt a small number of images, which greatly restricts its application in practice. In this paper, a new multi-image encryption method based on sinusoidal stripe coding [...] Read more.
Multi-image encryption technology is a vital branch of optical encryption technology. The traditional encryption method can only encrypt a small number of images, which greatly restricts its application in practice. In this paper, a new multi-image encryption method based on sinusoidal stripe coding frequency multiplexing and deep learning is proposed to realize the encryption of a greater number of images. In the process of encryption, several images are grouped, and each image in each group is first encoded with a random matrix and then modulated with a specific sinusoidal stripe; therefore, the dominant frequency of each group of images can be separated in the Fourier frequency domain. Each group is superimposed and scrambled to generate the final ciphertext. In the process of decryption, deep learning is used to improve the quality of decrypted image and the decryption speed. Specifically, the obtained ciphertext can be sent into the trained neural network and then the plaintext image can be reconstructed directly. Experimental analysis shows that when 32 images are encrypted, the CC of the decrypted result can reach more than 0.99. The efficiency of the proposed encryption method is proved in terms of histogram analysis, adjacent pixels correlation analysis, anti-noise attack analysis and resistance to occlusion attacks analysis. The encryption method has the advantages of large amount of information, good robustness and fast decryption speed. Full article
(This article belongs to the Special Issue Optical Imaging, Optical Sensing and Devices)
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Review

Jump to: Editorial, Research

35 pages, 8518 KiB  
Review
Fourier Domain Mode Locked Laser and Its Applications
by Dongmei Huang, Yihuan Shi, Feng Li and P. K. A. Wai
Sensors 2022, 22(9), 3145; https://0-doi-org.brum.beds.ac.uk/10.3390/s22093145 - 20 Apr 2022
Cited by 11 | Viewed by 3086
Abstract
The sweep rate of conventional short-cavity lasers with an intracavity-swept filter is limited by the buildup time of laser signals from spontaneous emissions. The Fourier domain mode-locked (FDML) laser was proposed to overcome the limitations of buildup time by inserting a long fiber [...] Read more.
The sweep rate of conventional short-cavity lasers with an intracavity-swept filter is limited by the buildup time of laser signals from spontaneous emissions. The Fourier domain mode-locked (FDML) laser was proposed to overcome the limitations of buildup time by inserting a long fiber delay in the cavity to store the whole swept signal and has attracted much interest in both theoretical and experimental studies. In this review, the theoretical models to understand the dynamics of the FDML laser and the experimental techniques to realize high speed, wide sweep range, long coherence length, high output power and highly stable swept signals in FDML lasers will be discussed. We will then discuss the applications of FDML lasers in optical coherence tomography (OCT), fiber sensing, precision measurement, microwave generation and nonlinear microscopy. Full article
(This article belongs to the Special Issue Optical Imaging, Optical Sensing and Devices)
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