High-power, widely wavelength-tunable, single-frequency pulsed fiber master oscillator power amplifier at 2.8 μm
Zongxiao Fan, Wenshu Liu, Zhehao Wu, Shengyi Wang... and Yong Liu|Show fewer author(s)
We present a high-power mid-infrared single-frequency pulsed fiber laser (SFPFL) with a tunable wavelength range from 2712.3 to 2793.2 nm. The single-frequency operation is achieved through a compound cavity design that incorporates a germanium etalon and a diffraction grating, resulting in an exceptionally narrow seed linewidth of approximately 780 kHz. Employing a master oscillator power amplifier configuration, we attain a maximum average output power of 2.6 W at 2789.4 nm, with a pulse repetition rate of 173 kHz, a pulse energy of 15 μJ and a narrow linewidth of approximately 850 kHz. This achievement underscores the potential of the mid-infrared SFPFL system for applications requiring high coherence and high power, such as high-resolution molecular spectroscopy, precision chemical identification and nonlinear frequency conversion.We present a high-power mid-infrared single-frequency pulsed fiber laser (SFPFL) with a tunable wavelength range from 2712.3 to 2793.2 nm. The single-frequency operation is achieved through a compound cavity design that incorporates a germanium etalon and a diffraction grating, resulting in an exceptionally narrow seed linewidth of approximately 780 kHz. Employing a master oscillator power amplifier configuration, we attain a maximum average output power of 2.6 W at 2789.4 nm, with a pulse repetition rate of 173 kHz, a pulse energy of 15 μJ and a narrow linewidth of approximately 850 kHz. This achievement underscores the potential of the mid-infrared SFPFL system for applications requiring high coherence and high power, such as high-resolution molecular spectroscopy, precision chemical identification and nonlinear frequency conversion.
- May. 14, 2025
- High Power Laser Science and Engineering
- Vol. 13, Issue 2, 02000e26 (2025)
- DOI：10.1017/hpl.2025.13
Concept and experimental demonstration of physics-guided end-to-end learning for optical communication systems
Qiarong Xiao, Chen Ding, Tengji Xu, Chester Shu, and Chaoran Huang
Driven by advancements in artificial intelligence, end-to-end learning has become a key method for system optimization in various fields, including communications. However, applying learning algorithms such as backpropagation directly to communication systems is challenging due to their non-differentiable nature. Existing methods typically require developing a precise differentiable digital model of the physical system, which is computationally complex and can cause significant performance loss after deployment. In response, we propose a novel end-to-end learning framework called physics-guided learning. This approach performs the forward pass through the actual transmission channel while simplifying the channel model for the backward pass to a simple white-box model. Despite the simplicity, both experimental and simulation results show that our method significantly outperforms other learning approaches for digital pre-distortion applications in coherent optical fiber systems. It enhances training speed and accuracy, reducing the number of training iterations by more than 80%. It improves transmission quality and noise resilience and offers superior generalization to varying transmission link conditions such as link losses, modulation formats, and scenarios with different transmission distances and optical amplification. Furthermore, our new end-to-end learning framework shows promise for broader applications in optimizing future communication systems, paving the way for more flexible and intelligent network designs.Driven by advancements in artificial intelligence, end-to-end learning has become a key method for system optimization in various fields, including communications. However, applying learning algorithms such as backpropagation directly to communication systems is challenging due to their non-differentiable nature. Existing methods typically require developing a precise differentiable digital model of the physical system, which is computationally complex and can cause significant performance loss after deployment. In response, we propose a novel end-to-end learning framework called physics-guided learning. This approach performs the forward pass through the actual transmission channel while simplifying the channel model for the backward pass to a simple white-box model. Despite the simplicity, both experimental and simulation results show that our method significantly outperforms other learning approaches for digital pre-distortion applications in coherent optical fiber systems. It enhances training speed and accuracy, reducing the number of training iterations by more than 80%. It improves transmission quality and noise resilience and offers superior generalization to varying transmission link conditions such as link losses, modulation formats, and scenarios with different transmission distances and optical amplification. Furthermore, our new end-to-end learning framework shows promise for broader applications in optimizing future communication systems, paving the way for more flexible and intelligent network designs.
- May. 14, 2025
- Photonics Research
- Vol. 13, Issue 6, 1469 (2025)
- DOI：10.1364/PRJ.551798
Electron–phonon coupling enhanced by graphene/PZT heterostructure for infrared emission and optical information transmission
Kaixi Bi, Linyu Mei, Shuqi Han, Jialiang Chen... and Xiujian Chou|Show fewer author(s)
High-performance infrared emitters hold substantial importance in modern engineering and physics. Here, we introduce graphene/PZT (lead zirconate titanate) heterostructure as a new platform for the development of infrared source structure based on an electron–phonon coupling and emitting mechanism. A series of electrical characterizations including carrier mobility [11,361.55 cm2/(V·s)], pulse current (30 ms response time), and cycling stability (2000 cycles) modulated by polarized film was provided. Its maximum working temperature reaches ∼1041 K (∼768°C), and it was broken at 1173 K (∼900°C) within ∼1.2 s rise time and fall time. Based on Wien’s displacement law, the high temperature will lead to near–mid–far thermal infrared when the heterostructure is applied to external voltages, and obvious bright white light could be observed by the naked eye. The changing process has also been recorded by mobile phone. In subsequent infrared emitting applications, 11 V bias voltage was applied on the PZT/graphene structure to produce the temperature change of ∼299 to 445 K within ∼0.96 s rise time and ∼0.98 s fall time. To demonstrate its optical information transmission ability, we exhibited “N, U, C” letters by the time-frequency method at 3 mm×3 mm@20 m condition. Combining with spatial Morse code infrared units, alphabetic information could also be transmitted by infrared array images. Compared with the traditional infrared emitter, the electron–phonon enhancing mechanism and high-performance emission properties of the heterostructure demonstrated a novel and reliable platform for further infrared optical applications.High-performance infrared emitters hold substantial importance in modern engineering and physics. Here, we introduce graphene/PZT (lead zirconate titanate) heterostructure as a new platform for the development of infrared source structure based on an electron–phonon coupling and emitting mechanism. A series of electrical characterizations including carrier mobility [
- May. 14, 2025
- Photonics Research
- Vol. 13, Issue 6, 1459 (2025)
- DOI：10.1364/PRJ.544524
Solar-blind ultraviolet imaging with a diamond metalens
Wen-Jie Dou, Xun Yang, Cheng-Long Zheng, Hua-Ping Zang... and Chong-Xin Shan|Show fewer author(s)
Imaging in the solar blind ultraviolet (UV) region offers significant advantages, including minimal interference from sunlight, reduced background noise, low false-alarm rate, and high sensitivity, and thus has important applications in early warning or detection of fire, ozone depletion, dynamite explosions, missile launches, electric leakage, etc. However, traditional imaging systems in this spectrum are often hindered by the bulkiness and complexity of conventional optics, resulting in heavy and cumbersome setups. The advent of metasurfaces, which use a two-dimensional array of nano-antennas to manipulate light properties, provides a powerful solution for developing miniaturized and compact optical systems. In this study, diamond metalenses were designed and fabricated to enable ultracompact solar-blind UV imaging. To prove this concept, two representative functionalities, bright-field imaging and spiral phase contrast imaging, were demonstrated as examples. Leveraging diamond’s exceptional properties, such as its wide bandgap, high refractive index, remarkable chemical inertness, and high damage threshold, this work not only presents a simple and feasible approach to realize solar-blind imaging in an ultracompact form but also highlights diamond as a highly capable material for developing miniaturized, lightweight, and robust imaging systems.Imaging in the solar blind ultraviolet (UV) region offers significant advantages, including minimal interference from sunlight, reduced background noise, low false-alarm rate, and high sensitivity, and thus has important applications in early warning or detection of fire, ozone depletion, dynamite explosions, missile launches, electric leakage, etc. However, traditional imaging systems in this spectrum are often hindered by the bulkiness and complexity of conventional optics, resulting in heavy and cumbersome setups. The advent of metasurfaces, which use a two-dimensional array of nano-antennas to manipulate light properties, provides a powerful solution for developing miniaturized and compact optical systems. In this study, diamond metalenses were designed and fabricated to enable ultracompact solar-blind UV imaging. To prove this concept, two representative functionalities, bright-field imaging and spiral phase contrast imaging, were demonstrated as examples. Leveraging diamond’s exceptional properties, such as its wide bandgap, high refractive index, remarkable chemical inertness, and high damage threshold, this work not only presents a simple and feasible approach to realize solar-blind imaging in an ultracompact form but also highlights diamond as a highly capable material for developing miniaturized, lightweight, and robust imaging systems.
- May. 14, 2025
- Photonics Research
- Vol. 13, Issue 6, 1452 (2025)
- DOI：10.1364/PRJ.555036
Modularized control of broadband surface-enhanced infrared absorption spectroscopy realized in over-coupled metasurfaces
Shiqing Dong, Dan Yang, Qian Wang, Haiyang Hu... and Hai Lu|Show fewer author(s)
We propose a modular designed over-coupled (OC) metasurface for the broadband surface-enhanced infrared absorption spectroscopy (SEIRAS) by analyzing the combined properties in the far field and near field. The customized sensors can independently modify the coupling mode, the resonance frequency, and the coupling efficiency by adjusting the vertical and horizontal structures and hybrid dielectric layers of the metasurface, respectively. Based on the independent regulation of the sensor properties, the influence of the detuning properties, the level of OC coupling, and the coupling efficiency of the signal amplification can be clearly presented through the single variable-controlling approach. These design principles are universal for customized sensors and herald possibilities for machine-learning-aided surface-enhanced infrared absorption (SEIRA) biosensing.We propose a modular designed over-coupled (OC) metasurface for the broadband surface-enhanced infrared absorption spectroscopy (SEIRAS) by analyzing the combined properties in the far field and near field. The customized sensors can independently modify the coupling mode, the resonance frequency, and the coupling efficiency by adjusting the vertical and horizontal structures and hybrid dielectric layers of the metasurface, respectively. Based on the independent regulation of the sensor properties, the influence of the detuning properties, the level of OC coupling, and the coupling efficiency of the signal amplification can be clearly presented through the single variable-controlling approach. These design principles are universal for customized sensors and herald possibilities for machine-learning-aided surface-enhanced infrared absorption (SEIRA) biosensing.
- May. 14, 2025
- Chinese Optics Letters
- Vol. 23, Issue 5, 053602 (2025)
- DOI：10.3788/COL202523.053602
Tactile-assisted point cloud super-resolution
Haoran Shen, Puzheng Wang, Ming Lu, Chi Zhang... and Qin Wang|Show fewer author(s)
With the rapid advancement of three-dimensional (3D) scanners and 3D point cloud acquisition technology, the application of 3D point clouds has been increasingly expanding in various fields. However, due to the limitations of 3D sensors, the collected point clouds are often sparse and non-uniform. In this work, we introduce local tactile information into the point cloud super-resolution task to aid in enhancing the resolution of the point cloud using fine-grained local details. Specifically, the local tactile point cloud is denser and more accurate compared to the low-resolution point cloud. By leveraging tactile information, we can obtain better local features. Therefore, we propose a feature extraction module that can efficiently fuse visual information with dense local tactile information. This module leverages the features from both modalities to achieve improved super-resolution results. In addition, we introduce a point cloud super-resolution dataset that includes tactile information. Qualitative and quantitative experiments show that our work performs much better than existing similar works that do not include tactile information, both in terms of handling low-resolution inputs and revealing high-fidelity details.With the rapid advancement of three-dimensional (3D) scanners and 3D point cloud acquisition technology, the application of 3D point clouds has been increasingly expanding in various fields. However, due to the limitations of 3D sensors, the collected point clouds are often sparse and non-uniform. In this work, we introduce local tactile information into the point cloud super-resolution task to aid in enhancing the resolution of the point cloud using fine-grained local details. Specifically, the local tactile point cloud is denser and more accurate compared to the low-resolution point cloud. By leveraging tactile information, we can obtain better local features. Therefore, we propose a feature extraction module that can efficiently fuse visual information with dense local tactile information. This module leverages the features from both modalities to achieve improved super-resolution results. In addition, we introduce a point cloud super-resolution dataset that includes tactile information. Qualitative and quantitative experiments show that our work performs much better than existing similar works that do not include tactile information, both in terms of handling low-resolution inputs and revealing high-fidelity details.
- May. 14, 2025
- Chinese Optics Letters
- Vol. 23, Issue 5, 051102 (2025)
- DOI：10.3788/COL202523.051102
High-performance multimode fiber specklegram sensing with a multi-layer convolutional neural network based on digital aperture filtering
Ya Wen, Xing Zhao, Zhixiang Jiang, and Da Li
Fiber specklegram sensors are widely studied for their high sensitivity and compact design. However, as the number of modes in the fiber increased, the speckle sensitivity heightened along with the correlation diminished, lowering the sensing performance. In this paper, an innovative method is introduced based on digital aperture filtering (DAF) that adopts physical principle analysis, which reduces the collection aperture by computationally screening out the energy of higher-order modes within the speckle, therefore enhancing the correlation among speckles. Subsequently, a multi-layer convolutional neural network is designed to accurately and efficiently identify the measurands represented from the filtered speckles. By comparing the experimental results of the speckle demodulation method on different multimode fibers in light field direction sensing, the DAF method has shown outstanding performance in sensing accuracy, sensing range, stability, resolution, and generalizability, fully demonstrating its tremendous potential in the advancement of fiber sensing technology.Fiber specklegram sensors are widely studied for their high sensitivity and compact design. However, as the number of modes in the fiber increased, the speckle sensitivity heightened along with the correlation diminished, lowering the sensing performance. In this paper, an innovative method is introduced based on digital aperture filtering (DAF) that adopts physical principle analysis, which reduces the collection aperture by computationally screening out the energy of higher-order modes within the speckle, therefore enhancing the correlation among speckles. Subsequently, a multi-layer convolutional neural network is designed to accurately and efficiently identify the measurands represented from the filtered speckles. By comparing the experimental results of the speckle demodulation method on different multimode fibers in light field direction sensing, the DAF method has shown outstanding performance in sensing accuracy, sensing range, stability, resolution, and generalizability, fully demonstrating its tremendous potential in the advancement of fiber sensing technology.
- May. 14, 2025
- Chinese Optics Letters
- Vol. 23, Issue 5, 051201 (2025)
- DOI：10.3788/COL202523.051201
Wavelength- and structure-insensitive on-chip mode manipulation based on the Thouless pumping mechanism
Yingdi Pan, Lu Sun, Jingchi Li, Qiyao Sun... and Yikai Su|Show fewer author(s)
Coupled-waveguide devices are essential in photonic integrated circuits for coupling, polarization handling, and mode manipulation. However, the performance of these devices usually suffers from high wavelength and structure sensitivity, which makes it challenging to realize broadband and reliable on-chip optical functions. Recently, topological pumping of edge states has emerged as a promising solution for implementing robust optical couplings. In this paper, we propose and experimentally demonstrate broadband on-chip mode manipulation with very large fabrication tolerance based on the Rice–Mele modeled silicon waveguide arrays. The Thouless pumping mechanism is employed in the design to implement broadband and robust mode conversion and multiplexing. The experimental results prove that various mode-order conversions with low insertion losses and intermodal crosstalk can be achieved over a broad bandwidth of 80 nm ranging from 1500 to 1580 nm. Thanks to such a topological design, the device has a remarkable fabrication tolerance of ±70 nm for the structural deviations in waveguide width and gap distance, which is, to the best of our knowledge, the highest among the coupled-waveguide mode-handling devices reported so far. As a proof-of-concept experiment, we cascade the topological mode-order converters to form a four-channel mode-division multiplexer and demonstrate the transmission of a 200-Gb/s 16-quadrature amplitude modulation signal for each mode channel, with the bit error rates below the 7% forward error correction threshold of 3.8 × 10 - 3. We reveal the possibility of developing new classes of broadband and fabrication-tolerant coupled-waveguide devices with topological photonic approaches, which may find applications in many fields, including optical interconnects, quantum communications, and optical computing.Coupled-waveguide devices are essential in photonic integrated circuits for coupling, polarization handling, and mode manipulation. However, the performance of these devices usually suffers from high wavelength and structure sensitivity, which makes it challenging to realize broadband and reliable on-chip optical functions. Recently, topological pumping of edge states has emerged as a promising solution for implementing robust optical couplings. In this paper, we propose and experimentally demonstrate broadband on-chip mode manipulation with very large fabrication tolerance based on the Rice–Mele modeled silicon waveguide arrays. The Thouless pumping mechanism is employed in the design to implement broadband and robust mode conversion and multiplexing. The experimental results prove that various mode-order conversions with low insertion losses and intermodal crosstalk can be achieved over a broad bandwidth of 80 nm ranging from 1500 to 1580 nm. Thanks to such a topological design, the device has a remarkable fabrication tolerance of ±70 nm for the structural deviations in waveguide width and gap distance, which is, to the best of our knowledge, the highest among the coupled-waveguide mode-handling devices reported so far. As a proof-of-concept experiment, we cascade the topological mode-order converters to form a four-channel mode-division multiplexer and demonstrate the transmission of a 200-Gb/s 16-quadrature amplitude modulation signal for each mode channel, with the bit error rates below the 7% forward error correction threshold of 3.8 × 10 - 3. We reveal the possibility of developing new classes of broadband and fabrication-tolerant coupled-waveguide devices with topological photonic approaches, which may find applications in many fields, including optical interconnects, quantum communications, and optical computing.
- May. 12, 2025
- Advanced Photonics Nexus
- Vol. 4, Issue 3, 036012 (2025)
- DOI：10.1117/1.APN.4.3.036012
Mapping ultrafast timing jitter in dispersion-managed 89 GHz frequency microcombs via self-heterodyne linear interferometry
Wenting Wang, Wenzheng Liu, Hao Liu, Tristan Melton... and Chee Wei Wong|Show fewer author(s)
Laser frequency microcombs provide a series of equidistant, coherent frequency markers across a broad spectrum, enabling advancements in laser spectroscopy, dense optical communications, precision distance metrology, and astronomy. Here, we design and fabricate silicon nitride, dispersion-managed microresonators that effectively suppress avoided-mode crossings and achieve close-to-zero averaged dispersion. Both the stochastic noise and mode-locking dynamics of the resonator are numerically and experimentally investigated. First, we experimentally demonstrate thermally stabilized microcomb formation in the microresonator across different mode-locked states, showing negligible center frequency shifts and a broad frequency bandwidth. Next, we characterize the femtosecond timing jitter of the microcombs, supported by precise metrology of the timing phase and relative intensity noise. For the single-soliton state, we report a relative intensity noise of -153.2 dB / Hz, close to the shot-noise limit, and a quantum-noise–limited timing jitter power spectral density of 0.4 as2 / Hz at a 100 kHz offset frequency, measured using a self-heterodyne linear interferometer. In addition, we achieve an integrated timing jitter of 1.7 fs ± 0.07 fs, measured from 10 kHz to 1 MHz. Measuring and understanding these fundamental noise parameters in high clock rate frequency microcombs is critical for advancing soliton physics and enabling new applications in precision metrology.Laser frequency microcombs provide a series of equidistant, coherent frequency markers across a broad spectrum, enabling advancements in laser spectroscopy, dense optical communications, precision distance metrology, and astronomy. Here, we design and fabricate silicon nitride, dispersion-managed microresonators that effectively suppress avoided-mode crossings and achieve close-to-zero averaged dispersion. Both the stochastic noise and mode-locking dynamics of the resonator are numerically and experimentally investigated. First, we experimentally demonstrate thermally stabilized microcomb formation in the microresonator across different mode-locked states, showing negligible center frequency shifts and a broad frequency bandwidth. Next, we characterize the femtosecond timing jitter of the microcombs, supported by precise metrology of the timing phase and relative intensity noise. For the single-soliton state, we report a relative intensity noise of -153.2 dB / Hz, close to the shot-noise limit, and a quantum-noise–limited timing jitter power spectral density of 0.4 as2 / Hz at a 100 kHz offset frequency, measured using a self-heterodyne linear interferometer. In addition, we achieve an integrated timing jitter of 1.7 fs ± 0.07 fs, measured from 10 kHz to 1 MHz. Measuring and understanding these fundamental noise parameters in high clock rate frequency microcombs is critical for advancing soliton physics and enabling new applications in precision metrology.
- May. 12, 2025
- Advanced Photonics Nexus
- Vol. 4, Issue 3, 036011 (2025)
- DOI：10.1117/1.APN.4.3.036011
Recent advances in tin perovskites and their applications
Feng Yang, Yu Tong, Kun Wang, Yali Chen... and Hongqiang Wang|Show fewer author(s)
Lead halide perovskites have started a new era for solar cells. However, the toxicity of lead poses a challenge for their practical applications. Replacing lead with tin provides a feasible way to reduce the toxicity of lead perovskites and can further promote the applications of perovskites. Due to their reduced toxicity with advantageous optical and electronic properties compared to their lead counterparts, tin (II) perovskites (TiPes) have attracted significant interest in recent years, not only for pursuing high-performance solar cells but also in other application fields. We aim to provide a comprehensive overview of recent advances in TiPes, covering fundamental crystal structure, optoelectronic properties, fabrication methods, and applications. A detailed comparison with lead perovskites is included, emphasizing TiPes’ unique strengths while presenting their application challenges. Finally, potential solutions to the challenges are proposed, along with a vision for their future development and potential.Lead halide perovskites have started a new era for solar cells. However, the toxicity of lead poses a challenge for their practical applications. Replacing lead with tin provides a feasible way to reduce the toxicity of lead perovskites and can further promote the applications of perovskites. Due to their reduced toxicity with advantageous optical and electronic properties compared to their lead counterparts, tin (II) perovskites (TiPes) have attracted significant interest in recent years, not only for pursuing high-performance solar cells but also in other application fields. We aim to provide a comprehensive overview of recent advances in TiPes, covering fundamental crystal structure, optoelectronic properties, fabrication methods, and applications. A detailed comparison with lead perovskites is included, emphasizing TiPes’ unique strengths while presenting their application challenges. Finally, potential solutions to the challenges are proposed, along with a vision for their future development and potential.
- May. 12, 2025
- Advanced Photonics
- Vol. 7, Issue 3, 034003 (2025)
- DOI：10.1117/1.AP.7.3.034003
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Call for Papers
Editor (s): Yuanjie Yang, Yangjian Cai, Qiwen Zhan
Innovative Optical Sensor Systems (2025)
Submission Open:15 January 2025; Submission Deadline: 30 April 2025
Editor (s): Nunzio Cennamo, Olivier Soppera, Giuseppe D’Aguanno, Yang Zhao
Emerging Coding Method for Computational Imaging (2025)
Submission Open:1 April 2025; Submission Deadline: 1 August 2025
Editor (s): Xin Yuan, David Brady, Enrique Tajahuerce, Jinli Suo... Liang Gao and Ni Chen|Show fewer author(s)
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