Pub Date : 2025-02-13DOI: 10.1109/JPHOT.2025.3532991
Lu Chen;Lifang Feng;Jianping Wang;Tianyi Zhang;Haijun Zhang;Zhuo Xue
Visible light positioning (VLP) is one of the effective solutions for low-cost and high-precision indoor positioning in the emerging wireless communication ecosystem, particularly in the context of 6G networks, due to its advantages of low latency, high data transmission rates, and immunity from radio frequency induced electromagnetic interference. However, severe performance limitations, including line-of-sight dependency, signal attenuation caused by obstacles, and restricted coverage, present a major challenge for the development of VLP. This article constructs an LED array-based hybrid indoor positioning system. An innovative LED array beacon is developed to simultaneously transmit coordinate and graphical information. A hybrid receiving structure, comprising an image sensor (IS) and a photodetector (PD), is constructed along with a dedicated hybrid positioning algorithm. This algorithm leverages image processing techniques to track the target trajectory, converts light intensity to identify the identification of LED, which finally resolves the target's precise world coordinates. The system's performance was validated through three experimental trials. The results demonstrate that the proposed beacon effectively covers the entire positioning area, achieving an average positioning error of 8.32 cm and a maximum positioning distance of 6.8 m. These results suggest that the proposed system provides a robust and efficient solution for precise indoor positioning applications in next-generation wireless communication networks.
{"title":"Hybrid Indoor Positioning System Based on LED Array","authors":"Lu Chen;Lifang Feng;Jianping Wang;Tianyi Zhang;Haijun Zhang;Zhuo Xue","doi":"10.1109/JPHOT.2025.3532991","DOIUrl":"https://doi.org/10.1109/JPHOT.2025.3532991","url":null,"abstract":"Visible light positioning (VLP) is one of the effective solutions for low-cost and high-precision indoor positioning in the emerging wireless communication ecosystem, particularly in the context of 6G networks, due to its advantages of low latency, high data transmission rates, and immunity from radio frequency induced electromagnetic interference. However, severe performance limitations, including line-of-sight dependency, signal attenuation caused by obstacles, and restricted coverage, present a major challenge for the development of VLP. This article constructs an LED array-based hybrid indoor positioning system. An innovative LED array beacon is developed to simultaneously transmit coordinate and graphical information. A hybrid receiving structure, comprising an image sensor (IS) and a photodetector (PD), is constructed along with a dedicated hybrid positioning algorithm. This algorithm leverages image processing techniques to track the target trajectory, converts light intensity to identify the identification of LED, which finally resolves the target's precise world coordinates. The system's performance was validated through three experimental trials. The results demonstrate that the proposed beacon effectively covers the entire positioning area, achieving an average positioning error of 8.32 cm and a maximum positioning distance of 6.8 m. These results suggest that the proposed system provides a robust and efficient solution for precise indoor positioning applications in next-generation wireless communication networks.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"17 2","pages":"1-11"},"PeriodicalIF":2.1,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10886945","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-06DOI: 10.1109/JPHOT.2025.3539420
Hannes F. Dreier;Ali Derakhshandeh;Andrej Harlakin;Peter A. Hoeher
A novel technique is proposed for estimating the angle-of-arrival (AOA) in free-space laser communication based on the shape of a laser beam spot on a flat surface. Two methods are introduced: one where ellipses are fitted to the intensity contour of the beam spot, and another where a least-squares fit of an AOA-dependent two-dimensional Gaussian distribution is applied to the intensity distribution. The effects of beam displacement, discretization, and noise on estimation performance are analyzed. The Cramér-Rao lower bound is derived and examined in relation to the true AOA. Both methods are verified through numerical simulations and experiments. For experimental validation, a novel beam sampling technique using a liquid-crystal display and a single photodiode is developed.
{"title":"Beam-Shape-Based Angle-of-Arrival Estimation in Free-Space Laser Communication","authors":"Hannes F. Dreier;Ali Derakhshandeh;Andrej Harlakin;Peter A. Hoeher","doi":"10.1109/JPHOT.2025.3539420","DOIUrl":"https://doi.org/10.1109/JPHOT.2025.3539420","url":null,"abstract":"A novel technique is proposed for estimating the angle-of-arrival (AOA) in free-space laser communication based on the shape of a laser beam spot on a flat surface. Two methods are introduced: one where ellipses are fitted to the intensity contour of the beam spot, and another where a least-squares fit of an AOA-dependent two-dimensional Gaussian distribution is applied to the intensity distribution. The effects of beam displacement, discretization, and noise on estimation performance are analyzed. The Cramér-Rao lower bound is derived and examined in relation to the true AOA. Both methods are verified through numerical simulations and experiments. For experimental validation, a novel beam sampling technique using a liquid-crystal display and a single photodiode is developed.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"17 2","pages":"1-16"},"PeriodicalIF":2.1,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10876596","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, a novel strategy of employing microwave photonic (MWP) time-frequency limiter (TFL) for microwave photonic multiband radar is proposed to suppress the interference, achieving real-time response to the interference scenarios and high-resolution target detection. By mapping the echo signal into optical domain, the time-frequency characteristic is re-constructed through stimulated Brillouin scattering (SBS), realizing the selective suppression on high-power optical signal mapped by the interference. Based on this concept, a MWP TFL system based on the optical spectrum processing is constructed, and proof-of-concept experiments are demonstrated to verify the feasibility of the proposed strategy under different interference scenarios. Employing the proposed MWP TFL, the signal-to-noise ratio of the detection results, which is severely degraded by asynchronous interference, can be improved by 27.97 dB, and the suppression ratio on the false targets generated by the synchronous interference can reach 34.10 dB. The experimental results shows that the strategy can further enhance the survivability of multiband radar without compromising the range resolution for target detection. In addition, experiments are carried out to demonstrate the capability of the proposed strategy under different interference-to-signal ratios, showing a good adaptability to the complex interference scenarios.
{"title":"Multiband Radar Using Microwave Photonic Time-Frequency Limiter for Real-Time Detection in Interference Scenarios","authors":"Luhang Xing;Shangyuan Li;Xiaoxiao Xue;Xiaoping Zheng;Bingkun Zhou","doi":"10.1109/JPHOT.2025.3537684","DOIUrl":"https://doi.org/10.1109/JPHOT.2025.3537684","url":null,"abstract":"In this paper, a novel strategy of employing microwave photonic (MWP) time-frequency limiter (TFL) for microwave photonic multiband radar is proposed to suppress the interference, achieving real-time response to the interference scenarios and high-resolution target detection. By mapping the echo signal into optical domain, the time-frequency characteristic is re-constructed through stimulated Brillouin scattering (SBS), realizing the selective suppression on high-power optical signal mapped by the interference. Based on this concept, a MWP TFL system based on the optical spectrum processing is constructed, and proof-of-concept experiments are demonstrated to verify the feasibility of the proposed strategy under different interference scenarios. Employing the proposed MWP TFL, the signal-to-noise ratio of the detection results, which is severely degraded by asynchronous interference, can be improved by 27.97 dB, and the suppression ratio on the false targets generated by the synchronous interference can reach 34.10 dB. The experimental results shows that the strategy can further enhance the survivability of multiband radar without compromising the range resolution for target detection. In addition, experiments are carried out to demonstrate the capability of the proposed strategy under different interference-to-signal ratios, showing a good adaptability to the complex interference scenarios.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"17 2","pages":"1-8"},"PeriodicalIF":2.1,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10870138","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143430457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-04DOI: 10.1109/JPHOT.2025.3537979
Yunhao Zhu;Chuanfei Yao;Xuan Wang;Guochuan Ren;Shu Liu;Jiaqian Si;Pingxue Li
An ultralow insertion loss (IL) and ultrahigh polarization extinction ratio (PER) single-polarization (SP) coupler based on dual-core photonic bandgap fiber (DC-PBF) with thin slab waveguide (TSW) is proposed. By introducing the TSW structure into the DC-PBF, the loss of the secondary eigenstate of polarization (ESOP) mode is significantly increased through the strong mode coupling with the higher-order TE/TM mode of the TSW. Thus, the SP performance is achieved through the significantly high loss of the secondary ESOP mode in conjunction with the relatively low loss of the primary ESOP mode. In order to design ultralow IL and ultrahigh PER SP couplers based on DC-PBF with TSW, the low-loss SP DC-PBF with TSW is established by considering the impacts of structure parameters and wavelength on both loss and coupling performance. Furthermore, the dependences of powers, coupling ratio, and PER in x(y)-polarization in two cores with different lengths are analyzed for the SP coupler based on DC-PBF with TSW. Finally, three ultralow IL and ultrahigh PER 3 dB SP couplers based on DC-PBF with TSW are designed through theoretical calculation of fabrication tolerance and operation bandwidth. These couplers exhibit narrow-band high PER (∼ 27.2 dB), short-length ultralow IL (∼ 0.00054 dB), and long-length ultrahigh PER (∼ 61.88 dB), respectively. The proposed ultralow IL and ultrahigh PER SP couplers based on DC-PBF with TSW have potential applications in high-precision resonant PBF optic gyroscopes as well as other PBF applications.
{"title":"Single-Polarization Coupler Based on Dual-Core Photonic Bandgap Fiber With Thin Slab Waveguide","authors":"Yunhao Zhu;Chuanfei Yao;Xuan Wang;Guochuan Ren;Shu Liu;Jiaqian Si;Pingxue Li","doi":"10.1109/JPHOT.2025.3537979","DOIUrl":"https://doi.org/10.1109/JPHOT.2025.3537979","url":null,"abstract":"An ultralow insertion loss (IL) and ultrahigh polarization extinction ratio (PER) single-polarization (SP) coupler based on dual-core photonic bandgap fiber (DC-PBF) with thin slab waveguide (TSW) is proposed. By introducing the TSW structure into the DC-PBF, the loss of the secondary eigenstate of polarization (ESOP) mode is significantly increased through the strong mode coupling with the higher-order TE/TM mode of the TSW. Thus, the SP performance is achieved through the significantly high loss of the secondary ESOP mode in conjunction with the relatively low loss of the primary ESOP mode. In order to design ultralow IL and ultrahigh PER SP couplers based on DC-PBF with TSW, the low-loss SP DC-PBF with TSW is established by considering the impacts of structure parameters and wavelength on both loss and coupling performance. Furthermore, the dependences of powers, coupling ratio, and PER in x(y)-polarization in two cores with different lengths are analyzed for the SP coupler based on DC-PBF with TSW. Finally, three ultralow IL and ultrahigh PER 3 dB SP couplers based on DC-PBF with TSW are designed through theoretical calculation of fabrication tolerance and operation bandwidth. These couplers exhibit narrow-band high PER (∼ 27.2 dB), short-length ultralow IL (∼ 0.00054 dB), and long-length ultrahigh PER (∼ 61.88 dB), respectively. The proposed ultralow IL and ultrahigh PER SP couplers based on DC-PBF with TSW have potential applications in high-precision resonant PBF optic gyroscopes as well as other PBF applications.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"17 2","pages":"1-6"},"PeriodicalIF":2.1,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10870402","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Highly light-absorbed encapsulation is generally used to eliminate the ambient light for light-emitting diode (LED) display devices, it is challenging to simultaneously achieve a high ambient contrast ratio (ACR) and high light output efficiency (LOE). To solve this problem, we propose an inverted packaging structure for LED display devices. The LED chips’ emitting surface is mounted on the transparent carrier board (TCB) while the backside is packaged by the composite encapsulation, causing that the substrate is inverted to the topside of devices. As a result, the chips can emit light directly from the TCB and avoid the absorption loss of the encapsulation, leading to the high ACR and LOE performances. Compared to traditional devices, the inverted device showed an average increase of over 800% in luminous flux (LF) and LOE, and an average increase of over 390% in ACR. Additionally, the devices exhibited excellent soldering performance, corrosion resistance, airtightness, and thermal stability. This novel device overcomes the bottleneck of achieving both high ACR and high LOE, providing new insights for the development of LED display technology. Future work can further optimize the structure and materials of the TCB and composite encapsulation to enhance device performance.
{"title":"High Ambient Contrast Ratio and Efficiency LED Display Devices Utilizing Inverted Packaging Structure","authors":"Zong-Tao Li;Yi-Hua Qiu;Jia-Sheng Li;Jin-Cheng Li;Bin-Hai Yu;Xin Zhu;Xin-Rui Ding","doi":"10.1109/JPHOT.2025.3537466","DOIUrl":"https://doi.org/10.1109/JPHOT.2025.3537466","url":null,"abstract":"Highly light-absorbed encapsulation is generally used to eliminate the ambient light for light-emitting diode (LED) display devices, it is challenging to simultaneously achieve a high ambient contrast ratio (ACR) and high light output efficiency (LOE). To solve this problem, we propose an inverted packaging structure for LED display devices. The LED chips’ emitting surface is mounted on the transparent carrier board (TCB) while the backside is packaged by the composite encapsulation, causing that the substrate is inverted to the topside of devices. As a result, the chips can emit light directly from the TCB and avoid the absorption loss of the encapsulation, leading to the high ACR and LOE performances. Compared to traditional devices, the inverted device showed an average increase of over 800% in luminous flux (LF) and LOE, and an average increase of over 390% in ACR. Additionally, the devices exhibited excellent soldering performance, corrosion resistance, airtightness, and thermal stability. This novel device overcomes the bottleneck of achieving both high ACR and high LOE, providing new insights for the development of LED display technology. Future work can further optimize the structure and materials of the TCB and composite encapsulation to enhance device performance.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"17 2","pages":"1-7"},"PeriodicalIF":2.1,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10859273","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-30DOI: 10.1109/JPHOT.2025.3536459
Xun Wang;Jingjing Hu;Yiying Gu;Xiaozhou Li;Shuai Zu;Dongxu Li
We propose and experimentally demonstrate a photonics method for generating broadband frequency hopping (FH) microwave signals based on an optoelectronic conversion (OEC) loop. In the proposed scheme, FH signals are generated after feedback modulation when low-frequency seed pulses are applied to the MZM in the OEC loop. The scheme can achieve a large-scale frequency hopping between S/C/X bands and C/X/Ku frequency bands. The experimental results indicate that 3-level FH signals with frequencies of 3/6/12 and 4/8/16 GHz have been successfully generated. Frequency-hopped linear frequency modulation (FH-LFM) signals from 2.5 GHz to 4.5 GHz, 5 GHz to 9 GHz and 10 GHz to 18 GHz with different chirp rates can also be generated. The achievable time-bandwidth product (TBWP) is as high as 15400. The autocorrelation results indicate that FH-LFM has good pulse compression ability. The pulse width, period and bandwidth of the FH signal can be adjusted flexibly. The proposed system does not require any optical filters or high-frequency RF signal source. It has potential to apply in radar, electronic warfare and wireless communication systems.
{"title":"Flexible Broadband Frequency Hopping Signal Generation Based on a Filter-Free Optoelectronic Conversion Loop","authors":"Xun Wang;Jingjing Hu;Yiying Gu;Xiaozhou Li;Shuai Zu;Dongxu Li","doi":"10.1109/JPHOT.2025.3536459","DOIUrl":"https://doi.org/10.1109/JPHOT.2025.3536459","url":null,"abstract":"We propose and experimentally demonstrate a photonics method for generating broadband frequency hopping (FH) microwave signals based on an optoelectronic conversion (OEC) loop. In the proposed scheme, FH signals are generated after feedback modulation when low-frequency seed pulses are applied to the MZM in the OEC loop. The scheme can achieve a large-scale frequency hopping between S/C/X bands and C/X/Ku frequency bands. The experimental results indicate that 3-level FH signals with frequencies of 3/6/12 and 4/8/16 GHz have been successfully generated. Frequency-hopped linear frequency modulation (FH-LFM) signals from 2.5 GHz to 4.5 GHz, 5 GHz to 9 GHz and 10 GHz to 18 GHz with different chirp rates can also be generated. The achievable time-bandwidth product (TBWP) is as high as 15400. The autocorrelation results indicate that FH-LFM has good pulse compression ability. The pulse width, period and bandwidth of the FH signal can be adjusted flexibly. The proposed system does not require any optical filters or high-frequency RF signal source. It has potential to apply in radar, electronic warfare and wireless communication systems.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"17 2","pages":"1-7"},"PeriodicalIF":2.1,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10858393","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143430408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-30DOI: 10.1109/JPHOT.2025.3536485
Gihong Park;Hoon Kim
Free-space optics (FSO) communication systems can be applied to cellular mobile communication networks to offer high-data-rate services to mobile users. In such networks, the exposure of optical receivers to direct sunlight could degrade the system performance and damage light-sensitive photo-detectors permanently. We investigate the average probability of the exposure of optical receiver to direct sunlight in FSO-based wireless mobile communication networks. We first estimate the probability of exposure to direct sunlight in open areas and then extend the theoretical analysis to the urban areas where the direct sunlight can be blocked by buildings. The validity of the analyses is evaluated through Monte Carlo simulations over a virtual city. The results show that the probability of exposure to direct sunlight ranges from 10−6 to 10−2, depending upon the receiver's field-of-view (FoV), latitude, average building heights, and the height of base stations (BSs). We also find out that the probabilities increase with the receiver's FoV to the power of 1.8 when the receiver's FoV is larger than the angular diameter of the sun. In urban areas, the probability decays exponentially with the average height of buildings exceeding the half of the BS height. The results also show that the probability rises with the BS height to the power of ∼2.6 under the same conditions. Finally, we estimate the outage time of FSO-based wireless mobile communications occurring by the exposure to direct sunlight. When the receiver's FoVs are 1 and 10 degrees, the outage times are estimated to be <1 and <35 hour/year, respectively, for the BS height of 28 m. The findings of this work could be used to estimate the probabilities of exposure to direct sunlight in various optical systems operating outdoors.
{"title":"Probability of Exposure of Optical Receiver to Direct Sunlight in FSO-Based Wireless Mobile Communications","authors":"Gihong Park;Hoon Kim","doi":"10.1109/JPHOT.2025.3536485","DOIUrl":"https://doi.org/10.1109/JPHOT.2025.3536485","url":null,"abstract":"Free-space optics (FSO) communication systems can be applied to cellular mobile communication networks to offer high-data-rate services to mobile users. In such networks, the exposure of optical receivers to direct sunlight could degrade the system performance and damage light-sensitive photo-detectors permanently. We investigate the average probability of the exposure of optical receiver to direct sunlight in FSO-based wireless mobile communication networks. We first estimate the probability of exposure to direct sunlight in open areas and then extend the theoretical analysis to the urban areas where the direct sunlight can be blocked by buildings. The validity of the analyses is evaluated through Monte Carlo simulations over a virtual city. The results show that the probability of exposure to direct sunlight ranges from 10<sup>−6</sup> to 10<sup>−2</sup>, depending upon the receiver's field-of-view (FoV), latitude, average building heights, and the height of base stations (BSs). We also find out that the probabilities increase with the receiver's FoV to the power of 1.8 when the receiver's FoV is larger than the angular diameter of the sun. In urban areas, the probability decays exponentially with the average height of buildings exceeding the half of the BS height. The results also show that the probability rises with the BS height to the power of ∼2.6 under the same conditions. Finally, we estimate the outage time of FSO-based wireless mobile communications occurring by the exposure to direct sunlight. When the receiver's FoVs are 1 and 10 degrees, the outage times are estimated to be <1 and <35 hour/year, respectively, for the BS height of 28 m. The findings of this work could be used to estimate the probabilities of exposure to direct sunlight in various optical systems operating outdoors.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"17 2","pages":"1-11"},"PeriodicalIF":2.1,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10858363","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The dual-comb spectrometer has emerged as a preferred instrument in multiheterodyne spectroscopy due to its high-resolution and fast-scanning capabilities. Conventional dual-comb spectroscopy (DCS) requires locking or reference systems, increasing both system complexity and cost, and limiting its commercial feasibility. Self-correction offers a promising alternative, though it demands a high refresh rate for interferograms (IGMs), corresponding to the repetition frequency difference, to counter system noise. This study examined the practical effects of self-correction at various refresh rates by measuring $rm H^{13}C^{14}N$ absorption. The results indicate that higher repetition frequency differences improve self-correction performance, while lower repetition frequencies cause deviations in absorption line width and intensity. Practical applications must balance measurement bandwidth, which is constrained by the repetition frequency difference.
{"title":"Self-Correction in Free-Running Dual-Comb Spectroscopy With Varying Interferogram Refresh Rates","authors":"Xiangze Ma;Wei Long;Jie Cheng;Yujia Ji;Teng Huang;Dijun Chen","doi":"10.1109/JPHOT.2025.3534022","DOIUrl":"https://doi.org/10.1109/JPHOT.2025.3534022","url":null,"abstract":"The dual-comb spectrometer has emerged as a preferred instrument in multiheterodyne spectroscopy due to its high-resolution and fast-scanning capabilities. Conventional dual-comb spectroscopy (DCS) requires locking or reference systems, increasing both system complexity and cost, and limiting its commercial feasibility. Self-correction offers a promising alternative, though it demands a high refresh rate for interferograms (IGMs), corresponding to the repetition frequency difference, to counter system noise. This study examined the practical effects of self-correction at various refresh rates by measuring <inline-formula><tex-math>$rm H^{13}C^{14}N$</tex-math></inline-formula> absorption. The results indicate that higher repetition frequency differences improve self-correction performance, while lower repetition frequencies cause deviations in absorption line width and intensity. Practical applications must balance measurement bandwidth, which is constrained by the repetition frequency difference.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"17 1","pages":"1-5"},"PeriodicalIF":2.1,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10854615","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143379521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We demonstrate Mach-Zehnder interferometer-based (MZI) athermal photonic devices using the structural compensation method. Unlike previous structural compensation studies that were applied on the thermal sensitive materials such as silicon, this work is implemented in tantalum pentoxide (Ta2O5) platform whose thermo-optic coefficient is low. This allows us to achieve ultra-athermalized filters by combining the structural compensation method and the material's own thermo-optic properties. Two types of devices are proposed: the asymmetric Mach-Zehnder interferometer (AMZI) and the ring-coupled Mach-Zehnder interferometer (RMZI). The temperature-dependent wavelength shift (TDWS) of the AMZI device is only 1.98 pm/K around 1550 nm which is 4.6 times smaller than a regular MZI. The TDWS remains below 2.23 pm/K across a broad bandwidth from 1480 nm to 1580 nm. By breaking the linear dependence between the wavelength shift and the temperature change, the maximum resonance drift can be restricted by using a ring-coupled MZI. Owning to Fano effect, the transmission spectrum of the RMZI device exhibits an oscillating behavior when facing temperature changes. This work proves the effectiveness of structural compensation method on an already low thermo-optic photonic platform, paving the way towards realization of ultra-athermal integrated optical filters in a low-loss and CMOS-compatible platform.
{"title":"Athermal Tantalum Pentoxide Mach-Zehnder Interferometers Based on Structural Compensation Method","authors":"Mingjian You;Zhenyu Liu;Weiren Cheng;Xingyu Tang;Ning Ding;Zhengqi Li;Min Wang;Li Shen;Qiancheng Zhao","doi":"10.1109/JPHOT.2025.3534244","DOIUrl":"https://doi.org/10.1109/JPHOT.2025.3534244","url":null,"abstract":"We demonstrate Mach-Zehnder interferometer-based (MZI) athermal photonic devices using the structural compensation method. Unlike previous structural compensation studies that were applied on the thermal sensitive materials such as silicon, this work is implemented in tantalum pentoxide (Ta<sub>2</sub>O<sub>5</sub>) platform whose thermo-optic coefficient is low. This allows us to achieve ultra-athermalized filters by combining the structural compensation method and the material's own thermo-optic properties. Two types of devices are proposed: the asymmetric Mach-Zehnder interferometer (AMZI) and the ring-coupled Mach-Zehnder interferometer (RMZI). The temperature-dependent wavelength shift (TDWS) of the AMZI device is only 1.98 pm/K around 1550 nm which is 4.6 times smaller than a regular MZI. The TDWS remains below 2.23 pm/K across a broad bandwidth from 1480 nm to 1580 nm. By breaking the linear dependence between the wavelength shift and the temperature change, the maximum resonance drift can be restricted by using a ring-coupled MZI. Owning to Fano effect, the transmission spectrum of the RMZI device exhibits an oscillating behavior when facing temperature changes. This work proves the effectiveness of structural compensation method on an already low thermo-optic photonic platform, paving the way towards realization of ultra-athermal integrated optical filters in a low-loss and CMOS-compatible platform.","PeriodicalId":13204,"journal":{"name":"IEEE Photonics Journal","volume":"17 1","pages":"1-8"},"PeriodicalIF":2.1,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10854680","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143361151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-27DOI: 10.1109/JPHOT.2025.3534424
Sacha Grelet;Alejandro Martinez Jimenez;Patrick B. Montague;Adrian Podoleanu
Akinetic swept-sources are essential for high-speed optical coherence tomography (OCT) imaging. Time-stretched supercontinuum (TSSC) lasers have proven to be efficient for multi-MHz swept-sources. However, lack of low-noise broadband lasers and of large dispersion devices in the water low-absorption band at 1060 nm have limited the biomedical applications of TSSC lasers. In this letter, an approach to tune the wavelength around 1050 nm over 90 nm with low-noise at 10 MHz is presented. This is based on all-normal dispersion (ANDi) supercontinuum dynamics, and employs a long chirped fiber Bragg grating (CFBG) to time-stretch a broadband pulse with a duty cycle of 93% . Retinal images are demonstrated, with a sensitivity of 84 dB - approaching the shot noise limit. We believe this high-speed low-noise swept-source will greatly promote the development of OCT techniques for biomedical applications.
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