Laser diodes with narrow linewidth are essential for optical communication, spectral analysis, and precision measurement. This study reinterprets the linewidth narrowing mechanism in external-cavity diode lasers (ECDLs) from a perspective that the noise-induced frequency fluctuations are suppressed by the rapidly varying phase in frequency domain introduced by the external cavity. We highlight the importance of the localized high slope in the rising edge of the feedback spectrum in forming stable narrow linewidth laser modes. Based upon this understanding, we introduce an alternative to traditional Lorentzian optical feedback. We demonstrated that asymmetric lineshapes, such as Fano, can serve as the optical feedback of ECDLs with enhanced performance. Theoretical analysis and numerical simulations reveal that Fano-based external cavity lasers, benefiting from a feedback spectrum with a steeper local slope than Lorentz-based cavities, can achieve superior linewidth narrowing under the same fabrication conditions. This study offers a novel approach for the design and application of narrow linewidth laser diodes.
{"title":"Enhancing External Cavity Laser Diode Performance Through Optimized Fano Spectrum Feedback Configuration","authors":"Hongbo Qiao;Yunxiang Sun;Zhibiao Hao;Changzheng Sun;Lai Wang;Bing Xiong;Jian Wang;Hongtao Li;Yanjun Han;Lin Gan;Yi Luo","doi":"10.1109/JSTQE.2025.3536449","DOIUrl":"https://doi.org/10.1109/JSTQE.2025.3536449","url":null,"abstract":"Laser diodes with narrow linewidth are essential for optical communication, spectral analysis, and precision measurement. This study reinterprets the linewidth narrowing mechanism in external-cavity diode lasers (ECDLs) from a perspective that the noise-induced frequency fluctuations are suppressed by the rapidly varying phase in frequency domain introduced by the external cavity. We highlight the importance of the localized high slope in the rising edge of the feedback spectrum in forming stable narrow linewidth laser modes. Based upon this understanding, we introduce an alternative to traditional Lorentzian optical feedback. We demonstrated that asymmetric lineshapes, such as Fano, can serve as the optical feedback of ECDLs with enhanced performance. Theoretical analysis and numerical simulations reveal that Fano-based external cavity lasers, benefiting from a feedback spectrum with a steeper local slope than Lorentz-based cavities, can achieve superior linewidth narrowing under the same fabrication conditions. This study offers a novel approach for the design and application of narrow linewidth laser diodes.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"31 5: Quantum Materials and Quantum Devices","pages":"1-7"},"PeriodicalIF":4.3,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143465729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-28DOI: 10.1109/JSTQE.2025.3535573
Mahmud Elahi Akhter;Ibraheem Muhammad Moosa;Lubaba Tazrian Rahman;Mohammad Atiqul Islam;Sharnali Islam;Khaleda Ali
In recent years, the design of chip-based photonic systems has significantly moved towards Artificial Intelligence-assisted data-driven methods instead of conventional intuition and simulation-based ones. The time-consuming nature of traditional chip-design methods, coupled with their insufficient flexibility to accommodate rapidly evolving integrated circuit requirements, contributes to this situation. In this work, we propose a novel generative model for the inverse design of nanophotonic power splitters. Our proposed model generates power splitters from arbitrary response spectra from 1.46 to 1.63 μm with a central wavelength of 1.55 μm. The model employs machine learning and a quadratic programming solver, which consists of a linear regressor and a mixed integer quadric programming solver. It is deterministic due to its generator being a quadratic programming solver. We empirically show that the generated structures have error margins within 10-4% and 2×10-4% for any given arbitrary response spectra. Furthermore, we also show that the model is capable of handling and generating Out-of-Distribution responses and their associated devices. Our code and dataset are available here.
{"title":"A Novel Generative Inverse Approach Towards Silicon-Based Nano-Photonic Power Splitter Design Generation","authors":"Mahmud Elahi Akhter;Ibraheem Muhammad Moosa;Lubaba Tazrian Rahman;Mohammad Atiqul Islam;Sharnali Islam;Khaleda Ali","doi":"10.1109/JSTQE.2025.3535573","DOIUrl":"https://doi.org/10.1109/JSTQE.2025.3535573","url":null,"abstract":"In recent years, the design of chip-based photonic systems has significantly moved towards Artificial Intelligence-assisted data-driven methods instead of conventional intuition and simulation-based ones. The time-consuming nature of traditional chip-design methods, coupled with their insufficient flexibility to accommodate rapidly evolving integrated circuit requirements, contributes to this situation. In this work, we propose a novel generative model for the inverse design of nanophotonic power splitters. Our proposed model generates power splitters from arbitrary response spectra from 1.46 to 1.63 μm with a central wavelength of 1.55 μm. The model employs machine learning and a quadratic programming solver, which consists of a linear regressor and a mixed integer quadric programming solver. It is deterministic due to its generator being a quadratic programming solver. We empirically show that the generated structures have error margins within 10-4% and 2×10-4% for any given arbitrary response spectra. Furthermore, we also show that the model is capable of handling and generating Out-of-Distribution responses and their associated devices. Our code and dataset are available here.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"31 3: AI/ML Integrated Opto-electronics","pages":"1-8"},"PeriodicalIF":4.3,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143446310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-27DOI: 10.1109/JSTQE.2025.3534636
Vivswan Shah;Nathan Youngblood
Real-world analog systems, such as photonic neural networks, intrinsically suffer from noise that can impede model convergence and accuracy for a variety of deep learning models. In the presence of noise, some activation functions behave erratically or even amplify the noise. Specifically, ReLU, an activation function used ubiquitously in digital deep learning systems, not only poses a challenge to implement in analog hardware but has also been shown to perform worse than continuously differentiable activation functions. In this paper, we demonstrate that GELU and SiLU enable robust propagation of gradients in analog hardware because they are continuously differentiable functions. To analyze this cause of activation differences in the presence of noise, we used functional interpolation between ReLU and GELU/SiLU to perform analysis and training of convolutional, linear, and transformer networks on simulated analog hardware with different interpolated activation functions. We find that in ReLU, errors in the gradient due to noise are amplified during backpropagation, leading to a significant reduction in model performance. However, we observe that error amplification decreases as we move toward GELU/SiLU, until it is non-existent at GELU/SiLU demonstrating that continuously differentiable activation functions are $sim 100times$ more noise-resistant than conventional rectified activations for inputs near zero. Our findings provide guidance in selecting the appropriate activations to realize reliable and performant photonic and other analog hardware accelerators in several domains of machine learning, such as computer vision, signal processing, and beyond.
{"title":"Leveraging Continuously Differentiable Activation for Learning in Analog and Quantized Noisy Environments","authors":"Vivswan Shah;Nathan Youngblood","doi":"10.1109/JSTQE.2025.3534636","DOIUrl":"https://doi.org/10.1109/JSTQE.2025.3534636","url":null,"abstract":"Real-world analog systems, such as photonic neural networks, intrinsically suffer from noise that can impede model convergence and accuracy for a variety of deep learning models. In the presence of noise, some activation functions behave erratically or even amplify the noise. Specifically, ReLU, an activation function used ubiquitously in digital deep learning systems, not only poses a challenge to implement in analog hardware but has also been shown to perform worse than continuously differentiable activation functions. In this paper, we demonstrate that GELU and SiLU enable robust propagation of gradients in analog hardware because they are continuously differentiable functions. To analyze this cause of activation differences in the presence of noise, we used functional interpolation between ReLU and GELU/SiLU to perform analysis and training of convolutional, linear, and transformer networks on simulated analog hardware with different interpolated activation functions. We find that in ReLU, errors in the gradient due to noise are amplified during backpropagation, leading to a significant reduction in model performance. However, we observe that error amplification decreases as we move toward GELU/SiLU, until it is non-existent at GELU/SiLU demonstrating that continuously differentiable activation functions are <inline-formula><tex-math>$sim 100times$</tex-math></inline-formula> more noise-resistant than conventional rectified activations for inputs near zero. Our findings provide guidance in selecting the appropriate activations to realize reliable and performant photonic and other analog hardware accelerators in several domains of machine learning, such as computer vision, signal processing, and beyond.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"31 3: AI/ML Integrated Opto-electronics","pages":"1-9"},"PeriodicalIF":4.3,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Studies on laboratory animals are a crucial step in a wide range of fundamental and applied scientific investigations. In addition to ensuring that research methods are chosen correctly, it is also necessary to use them properly in order to obtain the maximum amount of reliable information. In this study, we analyze and compare laser speckle contrast imaging (LSCI) data obtained simultaneously from the intact skull area and from the thinned skull area of the young laboratory rat (1.5-months-old), while additionally introducing a physiological challenge in the form of blood loss. We describe the experimental setup and materials used and also outline the signal processing approach. Finally, we present the results obtained and provide a discussion comparing our findings with studies conducted by other researchers, as well as addressing both the highlights and limitations of the study. In summary, the investigations conducted indicate that a cranial preparation is needed to record reliable LSCI data for cerebral perfusion, and it is also found that moderate blood loss does not reduce cerebral blood flow to the level of its autoregulation impairment.
{"title":"Effect of Thinned-Skull Cranial Window on Monitoring Cerebral Blood Flow Using Laser Speckle Contrast Imaging","authors":"Nadezhda Golubova;Ivan Ryzhkov;Konstantin Lapin;Evgeniya Seryogina;Andrey Dunaev;Viktor Dremin;Elena Potapova","doi":"10.1109/JSTQE.2025.3533950","DOIUrl":"https://doi.org/10.1109/JSTQE.2025.3533950","url":null,"abstract":"Studies on laboratory animals are a crucial step in a wide range of fundamental and applied scientific investigations. In addition to ensuring that research methods are chosen correctly, it is also necessary to use them properly in order to obtain the maximum amount of reliable information. In this study, we analyze and compare laser speckle contrast imaging (LSCI) data obtained simultaneously from the intact skull area and from the thinned skull area of the young laboratory rat (1.5-months-old), while additionally introducing a physiological challenge in the form of blood loss. We describe the experimental setup and materials used and also outline the signal processing approach. Finally, we present the results obtained and provide a discussion comparing our findings with studies conducted by other researchers, as well as addressing both the highlights and limitations of the study. In summary, the investigations conducted indicate that a cranial preparation is needed to record reliable LSCI data for cerebral perfusion, and it is also found that moderate blood loss does not reduce cerebral blood flow to the level of its autoregulation impairment.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"31 4: Adv. in Neurophoton. for Non-Inv. Brain Mon.","pages":"1-8"},"PeriodicalIF":4.3,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143184377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gadolinium-doped gallium nitride implanted with oxygen and carbon show carrier-mediated spin mechanisms at room temperature. As-grown Gd-doped GaN grown by metal-organic chemical vapor deposition using a tris(cyclopentadienyl) gadolinium precursor shows Ordinary Hall Effect and no ferromagnetism at room temperature. Upon O or C implantation in Gd-doped GaN, Anomalous Hall Effect that is indicative of carrier-mediated spin and ferromagnetism is observed. A good crystal quality is maintained even after implantation. O and C favor interstitial sites and occupy deep-level acceptor-type states in Gd-doped GaN. Room-temperature spin and ferromagnetism that is induced by gadolinium in Gd-doped GaN is activated by O and C that occupy interstitial sites. Carrier-mediated mechanism for spin functionalities shows potential for the control and manipulation of spin as a quantum state in gallium nitride. This makes GaGdN:O/C a potential semiconductor material base of interest for room temperature spintronics and quantum information science applications. In this paper, doping of O and C in Gd-doped GaN using ion implantation, structural characterization using X-ray diffraction, and spin-related measurement using Advanced Hall Effect are investigated, and corresponding discussions are made.
{"title":"Spin Mechanisms in Gd-Doped GaN Implanted With Oxygen/Carbon at Room Temperature","authors":"Vishal Saravade;Amirhossein Ghods;Chuanle Zhou;Ian Ferguson","doi":"10.1109/JSTQE.2025.3534663","DOIUrl":"https://doi.org/10.1109/JSTQE.2025.3534663","url":null,"abstract":"Gadolinium-doped gallium nitride implanted with oxygen and carbon show carrier-mediated spin mechanisms at room temperature. As-grown Gd-doped GaN grown by metal-organic chemical vapor deposition using a tris(cyclopentadienyl) gadolinium precursor shows Ordinary Hall Effect and no ferromagnetism at room temperature. Upon O or C implantation in Gd-doped GaN, Anomalous Hall Effect that is indicative of carrier-mediated spin and ferromagnetism is observed. A good crystal quality is maintained even after implantation. O and C favor interstitial sites and occupy deep-level acceptor-type states in Gd-doped GaN. Room-temperature spin and ferromagnetism that is induced by gadolinium in Gd-doped GaN is activated by O and C that occupy interstitial sites. Carrier-mediated mechanism for spin functionalities shows potential for the control and manipulation of spin as a quantum state in gallium nitride. This makes GaGdN:O/C a potential semiconductor material base of interest for room temperature spintronics and quantum information science applications. In this paper, doping of O and C in Gd-doped GaN using ion implantation, structural characterization using X-ray diffraction, and spin-related measurement using Advanced Hall Effect are investigated, and corresponding discussions are made.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"31 5: Quantum Materials and Quantum Devices","pages":"1-9"},"PeriodicalIF":4.3,"publicationDate":"2025-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-20DOI: 10.1109/JSTQE.2025.3531878
Jau Yang Wu;Chi-En Chen;Chao-Hsin Wu;Gong-Ru Lin
We have proposed a modified structure called the “charge focusing” design of a single-photon avalanche diode, based on our previous work using TSMC's 0.18 μm HV CMOS technology. We have demonstrated that this modified structure can improve the electric field distribution in the photon absorption layer, which previously resulted in worse jitter performance. This modification enhances carrier collection efficiency and detector timing resolution, leading to better performance in various applications where the pre-modified structure had been used. Furthermore, we propose that the modified structure can also be combined with the Separate Absorption and Charge Multiplication (SACM) structure to achieve high photon detection efficiency at infrared wavelengths, by adding a Germanium (Ge) epitaxy layer on top of the silicon layer. Our simulations show that the charge focusing design brings many advantages, most notably reducing the electric field at the edge of the Ge layer in the SACM structure, which is commonly used in silicon photonic and CMOS technologies.
{"title":"CMOS Design of Ge-on-Si Single-Photon Avalanche Diode With Ultralow Noise and Jitter","authors":"Jau Yang Wu;Chi-En Chen;Chao-Hsin Wu;Gong-Ru Lin","doi":"10.1109/JSTQE.2025.3531878","DOIUrl":"https://doi.org/10.1109/JSTQE.2025.3531878","url":null,"abstract":"We have proposed a modified structure called the “charge focusing” design of a single-photon avalanche diode, based on our previous work using TSMC's 0.18 μm HV CMOS technology. We have demonstrated that this modified structure can improve the electric field distribution in the photon absorption layer, which previously resulted in worse jitter performance. This modification enhances carrier collection efficiency and detector timing resolution, leading to better performance in various applications where the pre-modified structure had been used. Furthermore, we propose that the modified structure can also be combined with the Separate Absorption and Charge Multiplication (SACM) structure to achieve high photon detection efficiency at infrared wavelengths, by adding a Germanium (Ge) epitaxy layer on top of the silicon layer. Our simulations show that the charge focusing design brings many advantages, most notably reducing the electric field at the edge of the Ge layer in the SACM structure, which is commonly used in silicon photonic and CMOS technologies.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"31 5: Quantum Materials and Quantum Devices","pages":"1-7"},"PeriodicalIF":4.3,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143184205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A neuroimaging technique during surgery can further complement preoperative fMRI and electrical brain stimulation (EBS) to optimize the localization of eloquent areas during glioma resection and could improve dramatically the surgical procedure and patient care. Hyperspectral optical imaging is a non-invasive technique that is able to monitor hemodynamic and metabolic responses during neurosurgery. This technique can be used to complement the cortical functional mapping during neurosurgical procedures. However, a robust quantification of biomarkers of brain functionality is required to assist neurosurgeons. It is also essential to calibrate acquisition devices with robust optical phantoms to test instrument reliability. In this work, we explore the possibility to use a combined liquid blood phantom with cytochrome contained yeast to evaluate the reliability of hyperspectral imaging to measure oxygenation and metabolic changes. We also used hyperspectral imaging for identifying motor and sensory areas of human patients during neurosurgery. The results showed that a blood phantom and commercial yeast can be used to validate the measurement of hemodynamic and metabolic changes. This homogeneous phantom provides an excellent means to verify the reliability of intraoperative optical setups before moving on to clinical application. We showed that a commercial hyperspectral camera combined with a white light illumination could be used for identifying functional brain areas using hemodynamic and metabolic biomarkers. We also observed significant changes of the oxidative state of cytochrome-c-oxidase in periarterial tissue which seems to give an indication of the metabolism of the tissue during cerebral activity.
{"title":"Intraoperative Hyperspectral Imaging for Mapping Brain Motor and Sensory Functions With the Measurements of Changes in Hemoglobin Oxygenation and Oxidation of Cytochrome-C-Oxidase","authors":"Charly Caredda;Frédéric Lange;Ilias Tachtsidis;Thiébaud Picart;Jacques Guyotat;Bruno Montcel","doi":"10.1109/JSTQE.2025.3531556","DOIUrl":"https://doi.org/10.1109/JSTQE.2025.3531556","url":null,"abstract":"A neuroimaging technique during surgery can further complement preoperative fMRI and electrical brain stimulation (EBS) to optimize the localization of eloquent areas during glioma resection and could improve dramatically the surgical procedure and patient care. Hyperspectral optical imaging is a non-invasive technique that is able to monitor hemodynamic and metabolic responses during neurosurgery. This technique can be used to complement the cortical functional mapping during neurosurgical procedures. However, a robust quantification of biomarkers of brain functionality is required to assist neurosurgeons. It is also essential to calibrate acquisition devices with robust optical phantoms to test instrument reliability. In this work, we explore the possibility to use a combined liquid blood phantom with cytochrome contained yeast to evaluate the reliability of hyperspectral imaging to measure oxygenation and metabolic changes. We also used hyperspectral imaging for identifying motor and sensory areas of human patients during neurosurgery. The results showed that a blood phantom and commercial yeast can be used to validate the measurement of hemodynamic and metabolic changes. This homogeneous phantom provides an excellent means to verify the reliability of intraoperative optical setups before moving on to clinical application. We showed that a commercial hyperspectral camera combined with a white light illumination could be used for identifying functional brain areas using hemodynamic and metabolic biomarkers. We also observed significant changes of the oxidative state of cytochrome-c-oxidase in periarterial tissue which seems to give an indication of the metabolism of the tissue during cerebral activity.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"31 4: Adv. in Neurophoton. for Non-Inv. Brain Mon.","pages":"1-14"},"PeriodicalIF":4.3,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10845158","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143513003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 : 2025-01-15DOI: 10.1109/JSTQE.2025.3529620
Vijay;Joyee Ghosh;Vivek Venkataraman
We propose integrated photonic sources based on spontaneous four-wave mixing (SFWM) in dispersion engineered silicon nitride (SiN) nanowaveguides capable of generating spectrally-pure polarization-entangled photon-pairs bridging the visible-NIR and telecom bands. A simple silica-clad SiN waveguide design with height 640 nm and width in the range 860–960 nm can generate polarization-entangled photon pairs that simultaneously offers high heralded single photon purity of $>$99% and concurrence upto 0.99, with signal and idler lying in the range $sim$736–740 nm and $sim$1460–1560 nm, respectively, employing a pulsed pump (BW $gtrsim$0.25–3 THz) of wavelength near $sim$1-$mu$m. Slightly different waveguide height of 620 nm and corresponding waveguide widths in the range 1040–1180 nm, offering the same purity and concurrence standards, can also address various quantum memories demonstrated at the visible-NIR wavelengths of $sim$775–800 nm with a telecom band interface. Such CMOS-compatible on-chip sources of spectrally-pure polarization-entangled photon pairs can potentially be employed in a scalable manner for various optical quantum technologies.
{"title":"CMOS-Compatible Source Design for Visible-Telecom Photon-Pairs With Simultaneous Polarization-Entanglement and Spectral-Purity","authors":"Vijay;Joyee Ghosh;Vivek Venkataraman","doi":"10.1109/JSTQE.2025.3529620","DOIUrl":"https://doi.org/10.1109/JSTQE.2025.3529620","url":null,"abstract":"We propose integrated photonic sources based on spontaneous four-wave mixing (SFWM) in dispersion engineered silicon nitride (SiN) nanowaveguides capable of generating spectrally-pure polarization-entangled photon-pairs bridging the visible-NIR and telecom bands. A simple silica-clad SiN waveguide design with height 640 nm and width in the range 860–960 nm can generate polarization-entangled photon pairs that simultaneously offers high heralded single photon purity of <inline-formula><tex-math>$>$</tex-math></inline-formula>99% and concurrence upto 0.99, with signal and idler lying in the range <inline-formula><tex-math>$sim$</tex-math></inline-formula>736–740 nm and <inline-formula><tex-math>$sim$</tex-math></inline-formula>1460–1560 nm, respectively, employing a pulsed pump (BW <inline-formula><tex-math>$gtrsim$</tex-math></inline-formula>0.25–3 THz) of wavelength near <inline-formula><tex-math>$sim$</tex-math></inline-formula>1-<inline-formula><tex-math>$mu$</tex-math></inline-formula>m. Slightly different waveguide height of 620 nm and corresponding waveguide widths in the range 1040–1180 nm, offering the same purity and concurrence standards, can also address various quantum memories demonstrated at the visible-NIR wavelengths of <inline-formula><tex-math>$sim$</tex-math></inline-formula>775–800 nm with a telecom band interface. Such CMOS-compatible on-chip sources of spectrally-pure polarization-entangled photon pairs can potentially be employed in a scalable manner for various optical quantum technologies.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"31 5: Quantum Materials and Quantum Devices","pages":"1-11"},"PeriodicalIF":4.3,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143106056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-15DOI: 10.1109/JSTQE.2025.3529911
Chenjiang Qian;Viviana Villafañe;Pedro Soubelet;Andreas V. Stier;Jonathan J. Finley
We investigate the coupling between an ensemble of individual emitters and multiple photons in a high-$Q$ cavity at the mesoscopic excitation level. The master equation theory is used to calculate the emission spectrum of the cavity QED system. The increasing excitation level not only pumps the system to the high-energy multi-emitter-photon states, but also introduces the pump-induced dephasing that suppresses the coherent energy exchange (coupling) between photons and emitters. When the emitter lifetime exceeds a threshold, we observe the mesoscopic excitation level i.e., the system is pumped to high energy states whilst the coherent couplings between these states are not yet suppressed. The mesoscopic excitation enables the couplings between multi-emitter-photon states, and thereby, paves the way to building quantum photonic devices based on multiple photons and nonlinear effects.
{"title":"Couplings Between Photons and Ensemble of Emitters in a High-$Q$ Cavity at Mesoscopic Excitation Levels","authors":"Chenjiang Qian;Viviana Villafañe;Pedro Soubelet;Andreas V. Stier;Jonathan J. Finley","doi":"10.1109/JSTQE.2025.3529911","DOIUrl":"https://doi.org/10.1109/JSTQE.2025.3529911","url":null,"abstract":"We investigate the coupling between an ensemble of individual emitters and multiple photons in a high-<inline-formula><tex-math>$Q$</tex-math></inline-formula> cavity at the mesoscopic excitation level. The master equation theory is used to calculate the emission spectrum of the cavity QED system. The increasing excitation level not only pumps the system to the high-energy multi-emitter-photon states, but also introduces the pump-induced dephasing that suppresses the coherent energy exchange (coupling) between photons and emitters. When the emitter lifetime exceeds a threshold, we observe the mesoscopic excitation level i.e., the system is pumped to high energy states whilst the coherent couplings between these states are not yet suppressed. The mesoscopic excitation enables the couplings between multi-emitter-photon states, and thereby, paves the way to building quantum photonic devices based on multiple photons and nonlinear effects.","PeriodicalId":13094,"journal":{"name":"IEEE Journal of Selected Topics in Quantum Electronics","volume":"31 5: Quantum Materials and Quantum Devices","pages":"1-8"},"PeriodicalIF":4.3,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143106051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-15DOI: 10.1109/JSTQE.2025.3529834
Lixia Zheng;Shi Luo;Yongqi Han;Yanna Zheng;Jin Wu;Weifeng Sun
With the rapid advancement of three-dimensional laser ranging imaging technology and the continuous expansion of array scale, more demanding requirements such as stronger anti-interference capability, higher precision, and lower power consumption are imposed on the readout circuit. Nevertheless, with the expansion of the array scale, the transmission of high-frequency clock signals is affected by crosstalk, delay mismatch, and the like, which leads to the degradation of chip performance. To avoid the crosstalk and noise interference caused by the long-distance tracking of high-frequency clock signals in large-scale arrays and to suppress the deterioration of detection accuracy resulting from the initial phase error, a readout circuit based on the built-in clock is designed. Each oscillator is controlled by the voltage control signal generated by the external phase-locked loop of the pixel, considering both the circuit performance and power consumption. Secondly, an event-driven array TDC (time-to-digital converter) circuit is proposed based on the characteristics of single-photon detection application scenarios and the features of the built-in clock array TDC. Based on the trigger condition of the detected return light, the pixel TDC circuit is effectively activated, which can effectively conserve circuit power in sparse photon detection scenarios. Finally, the circuit is taped out based on the TSMC 0.18 μm CMOS process, and the measurement results verify that the proposed GRO(gated ring oscillator) shared array readout circuit operates normally and can achieve a time resolution of 102 ps and a range of 417 ns, with an average power consumption of 0.32 mW per pixel.
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