Andrea Pertoldi, Jakob M Hauge, Patrick Bowen Montague, Poul Varming
Frequency modulation of narrow-linewidth lasers can cause coherent backscattering in cladding-pumped fiber amplifiers. This detrimental effect can be observed in Tm-based fiber amplifiers and can be an additional limitation for power scaling applications. We investigate such instabilities in Tm- and Tm/Ho-doped fiber amplifiers for a wide range of design parameters (active fiber length, pumping scheme, dopant type) and operation regimes (laser frequency tuning rate, amplifier gain). For each amplifier configuration, the backward-propagating (BP) signal is found to peak at a specific laser frequency tuning rate, with an amplitude and a frequency that increase with increasing amplifier gain and fiber length.
{"title":"Coherent instabilities in thulium-based fiber amplifiers induced by laser frequency modulation.","authors":"Andrea Pertoldi, Jakob M Hauge, Patrick Bowen Montague, Poul Varming","doi":"10.1364/OL.539160","DOIUrl":"10.1364/OL.539160","url":null,"abstract":"<p><p>Frequency modulation of narrow-linewidth lasers can cause coherent backscattering in cladding-pumped fiber amplifiers. This detrimental effect can be observed in Tm-based fiber amplifiers and can be an additional limitation for power scaling applications. We investigate such instabilities in Tm- and Tm/Ho-doped fiber amplifiers for a wide range of design parameters (active fiber length, pumping scheme, dopant type) and operation regimes (laser frequency tuning rate, amplifier gain). For each amplifier configuration, the backward-propagating (BP) signal is found to peak at a specific laser frequency tuning rate, with an amplitude and a frequency that increase with increasing amplifier gain and fiber length.</p>","PeriodicalId":19540,"journal":{"name":"Optics letters","volume":"49 22","pages":"6361-6364"},"PeriodicalIF":3.1,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142639480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Spectral scanning, which utilizes the dispersive effect of light, is a simple and robust method for solid-state beam steering in light detection and ranging (LiDAR) applications. Powered by a tunable laser source, optical frequency-domain reflectometry (OFDR) is a high-precision measurement scheme that is inherently compatible with spectral scanning. Here, we propose a spectral-scanning LiDAR based on OFDR technology and demonstrate that, by connecting the measured spectral reflectivity and group delay of the targets with the dispersion equation, their cloud point data can be obtained. Moreover, compared to the spectral-scanning LiDAR based on the frequency-modulated continuous-wave (FMCW) ranging method, our proposed LiDAR scheme offers a more than tenfold improvement in range resolution with a large number of angular pixels. This enhancement enables high-resolution 3D imaging along both the angular and range axes.
{"title":"High range resolution spectral-scanning LiDAR based on optical frequency-domain reflectometry.","authors":"Degangao Kong, Cheng Chen, Jiajun Wan, Yongqiang Wen, Xiaolei Zhang, Sujun Yuan, Xiaoping Liu","doi":"10.1364/OL.534930","DOIUrl":"10.1364/OL.534930","url":null,"abstract":"<p><p>Spectral scanning, which utilizes the dispersive effect of light, is a simple and robust method for solid-state beam steering in light detection and ranging (LiDAR) applications. Powered by a tunable laser source, optical frequency-domain reflectometry (OFDR) is a high-precision measurement scheme that is inherently compatible with spectral scanning. Here, we propose a spectral-scanning LiDAR based on OFDR technology and demonstrate that, by connecting the measured spectral reflectivity and group delay of the targets with the dispersion equation, their cloud point data can be obtained. Moreover, compared to the spectral-scanning LiDAR based on the frequency-modulated continuous-wave (FMCW) ranging method, our proposed LiDAR scheme offers a more than tenfold improvement in range resolution with a large number of angular pixels. This enhancement enables high-resolution 3D imaging along both the angular and range axes.</p>","PeriodicalId":19540,"journal":{"name":"Optics letters","volume":"49 22","pages":"6565-6568"},"PeriodicalIF":3.1,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142639516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiaoke Yin, Shaokun Liu, Le He, Wenzhen Li, Yang Chen, Nengli Dai, Jinyan Li
The long fiber length required for the amplification of bismuth-doped fiber (BDF) has hindered its practical application. In this paper, we propose and demonstrate a feasible method to improve the active absorption of bismuth active centers (BACs) by optimizing the drawing conditions, achieving a high gain with a short fiber length. The bismuth-doped phosphosilicate fiber (BPSF) preform was fabricated by the modified chemical vapor deposition (MCVD) process and drawn into fiber under nine different conditions. The results indicate that the active absorption of BACs increases as the drawing temperature increases and the drawing speed decreases within these drawing parameters. Meanwhile, the corresponding gain per unit length is improved. Furthermore, a maximum gain of 31.6 dB at 1350 nm with the >20 dB gain wavelength range of 1311-1401 nm was achieved in a double-pass double-pump configuration, using only 45 m BPSF. Meanwhile, the -3 dB bandwidth was 1328-1370 nm. The gain per unit length is 0.7 dB/m, which, to the best of our knowledge, is the highest gain per unit length reported for the BPSF.
掺铋光纤（BDF）放大所需的光纤长度较长，这阻碍了其实际应用。在本文中，我们提出并演示了一种可行的方法，通过优化拉丝条件来提高铋活性中心（BAC）的活性吸收，从而在较短的光纤长度下实现高增益。我们采用改良化学气相沉积（MCVD）工艺制作了掺铋磷硅酸盐光纤（BPSF）预型件，并在九种不同条件下将其拉伸成光纤。结果表明，在这些拉丝参数范围内，随着拉丝温度的升高和拉丝速度的降低，BAC 的活性吸收增加。同时，单位长度的相应增益也得到了提高。此外，在双通双泵配置中，仅使用 45 m BPSF，就实现了 1350 nm 波长处 31.6 dB 的最大增益，增益大于 20 dB 的波长范围为 1311-1401 nm。同时，-3 dB 带宽为 1328-1370 nm。单位长度增益为 0.7 dB/m，据我们所知，这是目前所报道的 BPSF 单位长度最高增益。
{"title":"Realizing 0.7 dB/m gain in O + E band by promoting BACs-P formation in bismuth-doped phosphosilicate fiber with double-pass configuration.","authors":"Xiaoke Yin, Shaokun Liu, Le He, Wenzhen Li, Yang Chen, Nengli Dai, Jinyan Li","doi":"10.1364/OL.541880","DOIUrl":"10.1364/OL.541880","url":null,"abstract":"<p><p>The long fiber length required for the amplification of bismuth-doped fiber (BDF) has hindered its practical application. In this paper, we propose and demonstrate a feasible method to improve the active absorption of bismuth active centers (BACs) by optimizing the drawing conditions, achieving a high gain with a short fiber length. The bismuth-doped phosphosilicate fiber (BPSF) preform was fabricated by the modified chemical vapor deposition (MCVD) process and drawn into fiber under nine different conditions. The results indicate that the active absorption of BACs increases as the drawing temperature increases and the drawing speed decreases within these drawing parameters. Meanwhile, the corresponding gain per unit length is improved. Furthermore, a maximum gain of 31.6 dB at 1350 nm with the >20 dB gain wavelength range of 1311-1401 nm was achieved in a double-pass double-pump configuration, using only 45 m BPSF. Meanwhile, the -3 dB bandwidth was 1328-1370 nm. The gain per unit length is 0.7 dB/m, which, to the best of our knowledge, is the highest gain per unit length reported for the BPSF.</p>","PeriodicalId":19540,"journal":{"name":"Optics letters","volume":"49 22","pages":"6525-6528"},"PeriodicalIF":3.1,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142639550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yeasir Arafat, Abi Waqas, John Justice, Agnieszka Gocalinska, Fatih Atar, Eoin Russell, Brendan Roycroft, Darpan Mishra, Emanuele Pelucchi, Fatima Gunning, Brian Corbett
The short-wave infrared range is highly significant for spectroscopic sensing and upcoming optical communication applications. Integrating active and passive photonic components is essential to achieve compact optical solutions. In this paper, we show, for the first time to our knowledge, a wavelength-selective detection system based on the heterogeneous integration of two grating-coupled InGaAs photodetectors operating at the 2µm wave band, with a wavelength selectivity provided by a dual-channel Mach-Zehnder interferometer fabricated using a silicon-on-insulator (SOI) wafer. A full system responsivity of 0.1 A/W is measured together with >9.5 dB rejection ratio at two wavelengths. To our knowledge, we achieve the lowest measured dark current density (7.6 × 10-4 A/cm2 at -2 V) with micro-transfer printed integrated detectors.
{"title":"Silicon-on-insulator wavelength-selective filter with integrated detectors at the 2 µm wave band.","authors":"Yeasir Arafat, Abi Waqas, John Justice, Agnieszka Gocalinska, Fatih Atar, Eoin Russell, Brendan Roycroft, Darpan Mishra, Emanuele Pelucchi, Fatima Gunning, Brian Corbett","doi":"10.1364/OL.542147","DOIUrl":"10.1364/OL.542147","url":null,"abstract":"<p><p>The short-wave infrared range is highly significant for spectroscopic sensing and upcoming optical communication applications. Integrating active and passive photonic components is essential to achieve compact optical solutions. In this paper, we show, for the first time to our knowledge, a wavelength-selective detection system based on the heterogeneous integration of two grating-coupled InGaAs photodetectors operating at the 2µm wave band, with a wavelength selectivity provided by a dual-channel Mach-Zehnder interferometer fabricated using a silicon-on-insulator (SOI) wafer. A full system responsivity of 0.1 A/W is measured together with >9.5 dB rejection ratio at two wavelengths. To our knowledge, we achieve the lowest measured dark current density (7.6 × 10<sup>-4</sup> A/cm<sup>2</sup> at -2 V) with micro-transfer printed integrated detectors.</p>","PeriodicalId":19540,"journal":{"name":"Optics letters","volume":"49 22","pages":"6553-6556"},"PeriodicalIF":3.1,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142639554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1038/s41550-024-02409-2
Pedro Bernardinelli
A model for the formation of our Solar System proposes that its population of small bodies could have been formed after a stellar encounter between our Sun and another star early on in its history.
太阳系的一个形成模型提出，太阳系的小天体群可能是在其历史早期太阳与另一颗恒星相遇后形成的。
{"title":"Could the perfect stellar fly-by have shaped our Solar System?","authors":"Pedro Bernardinelli","doi":"10.1038/s41550-024-02409-2","DOIUrl":"10.1038/s41550-024-02409-2","url":null,"abstract":"A model for the formation of our Solar System proposes that its population of small bodies could have been formed after a stellar encounter between our Sun and another star early on in its history.","PeriodicalId":18778,"journal":{"name":"Nature Astronomy","volume":"8 11","pages":"1354-1355"},"PeriodicalIF":12.9,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1051/0004-6361/202348164
Bernhard Baumschlager, Sijing Shen, James W. Wadsley
Radiation from stars and active galactic nuclei (AGN) plays an important role in galaxy formation and evolution, and profoundly transforms the intergalactic, circumgalactic, and interstellar medium (IGM, CGM, and ISM). On-the-fly radiative transfer (RT) has started being incorporated in cosmological simulations, but the complex evolving radiation spectra are often crudely approximated with a small number of broad bands with piece-wise constant intensity and a fixed photo-ionisation cross-section. Such a treatment is unable to capture the changes to the spectrum as light is absorbed while it propagates through a medium with non-zero opacity. This can lead to large errors in photo-ionisation and heating rates. In this work we present a novel approach of discretising the radiation field at discrete photon energies, at the edges of the typically used photo-ionising bands, in order to capture the power-law slope of the radiation field. In combination with power-law approximations for the photo-ionisation cross-sections, this model allows us to self-consistently combine radiation from sources with different spectra and accurately follow the ionisation states of primordial and metal species through time. The method is implemented in GASOLINE2 in connection with TREVR2, a fast reverse ray tracing algorithm with 𝒪(Nactive log2N) scaling. We compare our new piece-wise power-law reconstruction to the piece-wise constant method in calculating the primordial chemistry photo-ionisation and heating rates under an evolving UV background (UVB) and stellar spectrum, and find that our method reduces errors significantly, by up to two orders of magnitude in the case of HeII ionisation. We apply our new spectral reconstruction method in RT post-processing of a cosmological zoom-in simulation, MUGS2 g1536, including radiation from stars and a live UVB, and find a significant increase in total neutral hydrogen (HI) mass in the ISM and the CGM due to shielding of the UVB and a low escape fraction of the stellar radiation. This demonstrates the importance of RT and an accurate spectral approximation in simulating the CGM-galaxy ecosystem.
{"title":"Spectral reconstruction for radiation hydrodynamic simulations of galaxy evolution","authors":"Bernhard Baumschlager, Sijing Shen, James W. Wadsley","doi":"10.1051/0004-6361/202348164","DOIUrl":"https://doi.org/10.1051/0004-6361/202348164","url":null,"abstract":"Radiation from stars and active galactic nuclei (AGN) plays an important role in galaxy formation and evolution, and profoundly transforms the intergalactic, circumgalactic, and interstellar medium (IGM, CGM, and ISM). On-the-fly radiative transfer (RT) has started being incorporated in cosmological simulations, but the complex evolving radiation spectra are often crudely approximated with a small number of broad bands with piece-wise constant intensity and a fixed photo-ionisation cross-section. Such a treatment is unable to capture the changes to the spectrum as light is absorbed while it propagates through a medium with non-zero opacity. This can lead to large errors in photo-ionisation and heating rates. In this work we present a novel approach of discretising the radiation field at discrete photon energies, at the edges of the typically used photo-ionising bands, in order to capture the power-law slope of the radiation field. In combination with power-law approximations for the photo-ionisation cross-sections, this model allows us to self-consistently combine radiation from sources with different spectra and accurately follow the ionisation states of primordial and metal species through time. The method is implemented in GASOLINE2 in connection with TREVR2, a fast reverse ray tracing algorithm with 𝒪(<i>N<i/><sub>active<sub/> log<sub>2<sub/> <i>N<i/>) scaling. We compare our new piece-wise power-law reconstruction to the piece-wise constant method in calculating the primordial chemistry photo-ionisation and heating rates under an evolving UV background (UVB) and stellar spectrum, and find that our method reduces errors significantly, by up to two orders of magnitude in the case of HeII ionisation. We apply our new spectral reconstruction method in RT post-processing of a cosmological zoom-in simulation, MUGS2 g1536, including radiation from stars and a live UVB, and find a significant increase in total neutral hydrogen (HI) mass in the ISM and the CGM due to shielding of the UVB and a low escape fraction of the stellar radiation. This demonstrates the importance of RT and an accurate spectral approximation in simulating the CGM-galaxy ecosystem.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"10 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142670265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1051/0004-6361/202451443
Miguel Araya
Context. Recently, the Nereides nebula was discovered through deep optical emission line observations and was classified as a supernova remnant (SNR) candidate, G107.7−5.1.Aims. Since very little is known about this SNR, we have looked at several archival datasets to better understand the environment and properties of the object.Methods. We present a detailed analysis of the gamma-ray emission detected by the Fermi Large Area Telescope in the region of the nebula. A model of the nonthermal emission is presented that allows us to derive the particle distribution responsible for the gamma rays. We also use molecular gas and atomic hydrogen observations to try to constrain the source age and distance.Results. An extended (∼2°) GeV source coincident with the location of the nebula is found. The nonthermal emission has a hard spectrum and is detected up to ∼100 GeV, confirming the SNR nature of this object. The GeV properties of G107.7−5.1 are similar to those of other SNRs such as G150.3 + 4.5, and it likely expands in a relatively low-density medium. The Nereides nebula is one more example of a growing population of dim SNRs detected at high energies. A simple leptonic model is able to account for the gamma-ray emission. Standard SNR evolutionary models constrain the age to be in the 10 − 50 kyr range, which is consistent with estimates of the maximum particle energy obtained from GeV observations. However, more detailed observations of the source should be carried out to better understand its properties.
{"title":"Nonthermal GeV emission from the Nereides nebula: Confirming the nature of the supernova remnant G107.7−5.1","authors":"Miguel Araya","doi":"10.1051/0004-6361/202451443","DOIUrl":"https://doi.org/10.1051/0004-6361/202451443","url":null,"abstract":"<i>Context.<i/> Recently, the Nereides nebula was discovered through deep optical emission line observations and was classified as a supernova remnant (SNR) candidate, G107.7−5.1.<i>Aims.<i/> Since very little is known about this SNR, we have looked at several archival datasets to better understand the environment and properties of the object.<i>Methods.<i/> We present a detailed analysis of the gamma-ray emission detected by the <i>Fermi<i/> Large Area Telescope in the region of the nebula. A model of the nonthermal emission is presented that allows us to derive the particle distribution responsible for the gamma rays. We also use molecular gas and atomic hydrogen observations to try to constrain the source age and distance.<i>Results.<i/> An extended (∼2°) GeV source coincident with the location of the nebula is found. The nonthermal emission has a hard spectrum and is detected up to ∼100 GeV, confirming the SNR nature of this object. The GeV properties of G107.7−5.1 are similar to those of other SNRs such as G150.3 + 4.5, and it likely expands in a relatively low-density medium. The Nereides nebula is one more example of a growing population of dim SNRs detected at high energies. A simple leptonic model is able to account for the gamma-ray emission. Standard SNR evolutionary models constrain the age to be in the 10 − 50 kyr range, which is consistent with estimates of the maximum particle energy obtained from GeV observations. However, more detailed observations of the source should be carried out to better understand its properties.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":"10 1","pages":""},"PeriodicalIF":6.5,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142670331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1038/s41377-024-01652-6
Dae-Myeong Geum, Jinha Lim, Junho Jang, Seungyeop Ahn, SeongKwang Kim, Joonsup Shim, Bong Ho Kim, Juhyuk Park, Woo Jin Baek, Jaeyong Jeong, SangHyeon Kim
This paper demonstrates the novel approach of sub-micron-thick InGaAs broadband photodetectors (PDs) designed for high-resolution imaging from the visible to short-wavelength infrared (SWIR) spectrum. Conventional approaches encounter challenges such as low resolution and crosstalk issues caused by a thick absorption layer (AL). Therefore, we propose a guided-mode resonance (GMR) structure to enhance the quantum efficiency (QE) of the InGaAs PDs in the SWIR region with only sub-micron-thick AL. The TiOx/Au-based GMR structure compensates for the reduced AL thickness, achieving a remarkably high QE (>70%) from 400 to 1700 nm with only a 0.98 μm AL InGaAs PD (defined as 1 μm AL PD). This represents a reduction in thickness by at least 2.5 times compared to previous results while maintaining a high QE. Furthermore, the rapid transit time is highly expected to result in decreased electrical crosstalk. The effectiveness of the GMR structure is evident in its ability to sustain QE even with a reduced AL thickness, simultaneously enhancing the transit time. This breakthrough offers a viable solution for high-resolution and low-noise broadband image sensors.
本文展示了亚微米厚 InGaAs 宽带光电探测器（PD）的新方法，该方法旨在实现从可见光到短波红外（SWIR）光谱的高分辨率成像。传统方法会遇到分辨率低和厚吸收层（AL）引起的串扰问题等挑战。因此，我们提出了一种导模共振（GMR）结构，以提高仅具有亚微米厚吸收层的 InGaAs PD 在 SWIR 区域的量子效率（QE）。基于 TiOx/Au 的 GMR 结构弥补了 AL 厚度的减少，在 400 纳米到 1700 纳米的范围内，仅用 0.98 μm AL InGaAs PD（定义为 1 μm AL PD）就实现了非常高的 QE（>70%）。与之前的结果相比，这意味着在保持高 QE 的同时，厚度至少减少了 2.5 倍。此外，快速传输时间有望减少电串扰。GMR 结构的有效性体现在，即使 AL 厚度减少，它仍能保持 QE，同时提高传输时间。这一突破为高分辨率和低噪声宽带图像传感器提供了可行的解决方案。
{"title":"Highly-efficient (>70%) and Wide-spectral (400-1700 nm) sub-micron-thick InGaAs photodiodes for future high-resolution image sensors.","authors":"Dae-Myeong Geum, Jinha Lim, Junho Jang, Seungyeop Ahn, SeongKwang Kim, Joonsup Shim, Bong Ho Kim, Juhyuk Park, Woo Jin Baek, Jaeyong Jeong, SangHyeon Kim","doi":"10.1038/s41377-024-01652-6","DOIUrl":"10.1038/s41377-024-01652-6","url":null,"abstract":"<p><p>This paper demonstrates the novel approach of sub-micron-thick InGaAs broadband photodetectors (PDs) designed for high-resolution imaging from the visible to short-wavelength infrared (SWIR) spectrum. Conventional approaches encounter challenges such as low resolution and crosstalk issues caused by a thick absorption layer (AL). Therefore, we propose a guided-mode resonance (GMR) structure to enhance the quantum efficiency (QE) of the InGaAs PDs in the SWIR region with only sub-micron-thick AL. The TiO<sub>x</sub>/Au-based GMR structure compensates for the reduced AL thickness, achieving a remarkably high QE (>70%) from 400 to 1700 nm with only a 0.98 μm AL InGaAs PD (defined as 1 μm AL PD). This represents a reduction in thickness by at least 2.5 times compared to previous results while maintaining a high QE. Furthermore, the rapid transit time is highly expected to result in decreased electrical crosstalk. The effectiveness of the GMR structure is evident in its ability to sustain QE even with a reduced AL thickness, simultaneously enhancing the transit time. This breakthrough offers a viable solution for high-resolution and low-noise broadband image sensors.</p>","PeriodicalId":18093,"journal":{"name":"Light, science & applications","volume":"13 1","pages":"311"},"PeriodicalIF":19.4,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11568205/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142639251","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chengzhen Bian, Bohan Sang, Xiongwei Yang, Chen Wang, Long Zhang, Yi Wei, Qiutong Zhang, Kaihui Wang, Wen Zhou, Jianjun Yu
We propose a multidimensional (MD) quadrature phase shift keying (QPSK) symbol modulation and demodulation scheme based on random sequence extraction, which overcomes the limitations of traditional QPSK signals in performing probabilistic shaping. Unlike probabilistic shaping (PS) and geometric shaping (GS), our approach does not require modifications to the existing digital signal processing (DSP) architecture; it only necessitates the addition of sequence modulation and demodulation modules. Additionally, the source entropy (SE) can be flexibly adjusted. An experimental verification was conducted in a 50 m, 150 GHz photonics-aided wireless communication system. The results show that, under the same net data rate, the random sequence extraction QPSK scheme can achieve a maximum optical power gain of 0.7 dB. These findings indicate that the random sequence extraction QPSK (SE-QPSK) scheme can effectively enhance system performance, providing a promising outlook for future wireless communication.
{"title":"Multidimensional QPSK symbol modulation scheme based on random sequence extraction for D-band photonics-aided wireless communication.","authors":"Chengzhen Bian, Bohan Sang, Xiongwei Yang, Chen Wang, Long Zhang, Yi Wei, Qiutong Zhang, Kaihui Wang, Wen Zhou, Jianjun Yu","doi":"10.1364/OL.542218","DOIUrl":"10.1364/OL.542218","url":null,"abstract":"<p><p>We propose a multidimensional (MD) quadrature phase shift keying (QPSK) symbol modulation and demodulation scheme based on random sequence extraction, which overcomes the limitations of traditional QPSK signals in performing probabilistic shaping. Unlike probabilistic shaping (PS) and geometric shaping (GS), our approach does not require modifications to the existing digital signal processing (DSP) architecture; it only necessitates the addition of sequence modulation and demodulation modules. Additionally, the source entropy (SE) can be flexibly adjusted. An experimental verification was conducted in a 50 m, 150 GHz photonics-aided wireless communication system. The results show that, under the same net data rate, the random sequence extraction QPSK scheme can achieve a maximum optical power gain of 0.7 dB. These findings indicate that the random sequence extraction QPSK (SE-QPSK) scheme can effectively enhance system performance, providing a promising outlook for future wireless communication.</p>","PeriodicalId":19540,"journal":{"name":"Optics letters","volume":"49 22","pages":"6425-6428"},"PeriodicalIF":3.1,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142639508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Quantum dots (QDs) exhibit excellent optical and chemical properties, making them advantageous for fluorescence sensing. However, gas sensor using QDs is often hampered by challenges such as gas diffusion and low concentration. This work describes the development of a nitrogen dioxide (NO2) fluorescence gas sensor that utilizes a QDs@Aerogels/SM composite nanofilm containing CdTe QDs modified by reduced glutathione (GSH), silica microspheres (SMs), and silica aerogel. The SM and porous aerogels create a uniform porous structure that enhances the distribution of QDs. Compared to the pure QDs film, the QDs@Aerogels/SM composite film exhibits enhanced fluorescence intensity. The porous structure promotes the adsorption of NO2, which improves the detection sensitivity. The QDs@Aerogels/SM composite film was applied in a portable gas sensor. The sensor demonstrates a good linear response to NO2 gas in the range of 0-10 ppm, with an ultra-low detection limit of 0.096 ppm and high selectivity. The uniform distribution of aerogel and SM enhances the stability of the composite nanofilm, and the fluorescence of the films remains virtually unchanged over a period of 60 days which ensures its optimal performance over extended periods of use. The fluorescent NO2 sensor demonstrated selective and sensitive quenching upon exposure to NO2, making it ideal for environmental monitoring and further applications.
{"title":"High-sensitivity NO<sub>2</sub> fluorescence sensor based on a QDs@Aerogels/SM composite nanofilm.","authors":"Heng Li, Yongxiao Chen, Wei Zhou, Guanjie Yang, Tian Xie, Qiuhua Li, Jianlin Huang, Cong Liu, Xiaobo Xing","doi":"10.1364/OL.529773","DOIUrl":"https://doi.org/10.1364/OL.529773","url":null,"abstract":"<p><p>Quantum dots (QDs) exhibit excellent optical and chemical properties, making them advantageous for fluorescence sensing. However, gas sensor using QDs is often hampered by challenges such as gas diffusion and low concentration. This work describes the development of a nitrogen dioxide (NO<sub>2</sub>) fluorescence gas sensor that utilizes a QDs@Aerogels/SM composite nanofilm containing CdTe QDs modified by reduced glutathione (GSH), silica microspheres (SMs), and silica aerogel. The SM and porous aerogels create a uniform porous structure that enhances the distribution of QDs. Compared to the pure QDs film, the QDs@Aerogels/SM composite film exhibits enhanced fluorescence intensity. The porous structure promotes the adsorption of NO<sub>2</sub>, which improves the detection sensitivity. The QDs@Aerogels/SM composite film was applied in a portable gas sensor. The sensor demonstrates a good linear response to NO<sub>2</sub> gas in the range of 0-10 ppm, with an ultra-low detection limit of 0.096 ppm and high selectivity. The uniform distribution of aerogel and SM enhances the stability of the composite nanofilm, and the fluorescence of the films remains virtually unchanged over a period of 60 days which ensures its optimal performance over extended periods of use. The fluorescent NO<sub>2</sub> sensor demonstrated selective and sensitive quenching upon exposure to NO<sub>2</sub>, making it ideal for environmental monitoring and further applications.</p>","PeriodicalId":19540,"journal":{"name":"Optics letters","volume":"49 22","pages":"6381-6384"},"PeriodicalIF":3.1,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142639520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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