Journals >Chinese Optics Letters
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2022
Volume: 20 Issue 4
17 Article(s)
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Research Articles
Fiber Optics and Optical Communications
Ultra-small interferometric fiber optic gyroscope with an integrated optical chip
Kejun Shang, Ming Lei, Haowei Li, Tianqi Zhang, Xiaozhi Yu, Qiang Xiang, Yonglin Na, and Lizhe Zhang
This study proposes a novel interferometric fiber optic gyroscope (IFOG) based on an integrated optical chip, application-specific integrated circuit, and small-diameter sensing coil. The overall size and weight of the prototype are 30 mm×30 mm×30 mm and 68 g, respectively, making it the smallest closed-loop IFOG, to the best of our knowledge. A static experiment shows that the bias stability of the integrated IFOG is very close to the theoretical accuracy limit determined by the fiber coil and can satisfy the requirements of near-navigation-grade compact inertial navigation systems.This study proposes a novel interferometric fiber optic gyroscope (IFOG) based on an integrated optical chip, application-specific integrated circuit, and small-diameter sensing coil. The overall size and weight of the prototype are
Chinese Optics Letters
- Publication Date: Feb. 16, 2022
- Vol. 20, Issue 4, 040601 (2022)
Highly efficient and stable coupling of kilowatt-level continuous wave laser into hollow-core fibers
Yulong Cui, Wei Huang, Zhiyue Zhou, Hao Li, Meng Wang, Zilun Chen, and Zefeng Wang
Fiber gas lasers based on gas-filled hollow-core fibers (HCFs) perfectly combine the advantages of fiber lasers and gas lasers and have obtained fast development in the past years. However, stable and efficient coupling of high-power pump lasers into the HCFs is one of the key problems to be solved. In this paper, we study the coupling of high-power continuous wave fiber lasers into anti-resonant HCFs through an end-cap. By optimizing the splicing parameters, a maximum laser power of 1167 W was injected into the 1-m-long HCFs, and 1021 W was obtained at the output end, giving a total transmission efficiency of ∼87.5%. A more than 1 h test showed the stability of such a coupling method. Meanwhile, the laser beam quality was well maintained. This work opens new opportunities for stable and highly efficient coupling of high-power lasers into HCFs, which is significant for its applications in many other fields besides high-power fiber gas lasers, such as high-power laser delivering.Fiber gas lasers based on gas-filled hollow-core fibers (HCFs) perfectly combine the advantages of fiber lasers and gas lasers and have obtained fast development in the past years. However, stable and efficient coupling of high-power pump lasers into the HCFs is one of the key problems to be solved. In this paper, we study the coupling of high-power continuous wave fiber lasers into anti-resonant HCFs through an end-cap. By optimizing the splicing parameters, a maximum laser power of 1167 W was injected into the 1-m-long HCFs, and 1021 W was obtained at the output end, giving a total transmission efficiency of
Chinese Optics Letters
- Publication Date: Feb. 14, 2022
- Vol. 20, Issue 4, 040602 (2022)
Michelson interferometer composite cavity fiber laser sensor with radio frequency interrogation
Xu Wang, Enlai Wang, and Fang Wang
A Michelson interferometer (MI) composite cavity fiber laser sensing system based on radio frequency (RF) interrogation is proposed and experimentally demonstrated. The system down-converts the traditional MI light frequency detection to RF detection, which improves the stability of the system. The optic fiber MI is placed in the laser resonator to form a composite cavity structure, which greatly improves the sensitivity of beat frequency signal demodulation.A Michelson interferometer (MI) composite cavity fiber laser sensing system based on radio frequency (RF) interrogation is proposed and experimentally demonstrated. The system down-converts the traditional MI light frequency detection to RF detection, which improves the stability of the system. The optic fiber MI is placed in the laser resonator to form a composite cavity structure, which greatly improves the sensitivity of beat frequency signal demodulation..
Chinese Optics Letters
- Publication Date: Feb. 16, 2022
- Vol. 20, Issue 4, 040603 (2022)
Imaging Systems and Image Processing
Deep learning-based scattering removal of light field imaging | Editors' Pick
Weihao Wang, Xing Zhao, Zhixiang Jiang, and Ya Wen
Light field imaging has shown significance in research fields for its high-temporal-resolution 3D imaging ability. However, in scenes of light field imaging through scattering, such as biological imaging in vivo and imaging in fog, the quality of 3D reconstruction will be severely reduced due to the scattering of the light field information. In this paper, we propose a deep learning-based method of scattering removal of light field imaging. In this method, a neural network, trained by simulation samples that are generated by light field imaging forward models with and without scattering, is utilized to remove the effect of scattering on light fields captured experimentally. With the deblurred light field and the scattering-free forward model, 3D reconstruction with high resolution and high contrast can be realized. We demonstrate the proposed method by using it to realize high-quality 3D reconstruction through a single scattering layer experimentally.Light field imaging has shown significance in research fields for its high-temporal-resolution 3D imaging ability. However, in scenes of light field imaging through scattering, such as biological imaging in vivo and imaging in fog, the quality of 3D reconstruction will be severely reduced due to the scattering of the light field information. In this paper, we propose a deep learning-based method of scattering removal of light field imaging. In this method, a neural network, trained by simulation samples that are generated by light field imaging forward models with and without scattering, is utilized to remove the effect of scattering on light fields captured experimentally. With the deblurred light field and the scattering-free forward model, 3D reconstruction with high resolution and high contrast can be realized. We demonstrate the proposed method by using it to realize high-quality 3D reconstruction through a single scattering layer experimentally..
Chinese Optics Letters
- Publication Date: Feb. 16, 2022
- Vol. 20, Issue 4, 041101 (2022)
Integrated Optics
Silicon photonics integrated dynamic polarization controller
Xuyang Wang, Yanxiang Jia, Xubo Guo, Jianqiang Liu, Shaofeng Wang, Wenyuan Liu, Fangyuan Sun, Jun Zou, and Yongmin Li
We designed and demonstrated experimentally a silicon photonics integrated dynamic polarization controller. The overall size of the dynamic polarization controller on chip is 2.830 mm×0.210 mm×1 mm. The modulation bandwidth is 30 kHz. By using a variable step simulated annealing approach, we achieve a dynamic polarization extinction ratio greater than 25 dB. A numerical simulation method was used to optimize the relevant parameters of the dynamic polarization controller. It is expected that the dynamic polarization controller can be utilized in fiber communication systems or silicon photonics integrated quantum communication systems to minimize the size and decrease the cost further.We designed and demonstrated experimentally a silicon photonics integrated dynamic polarization controller. The overall size of the dynamic polarization controller on chip is
Chinese Optics Letters
- Publication Date: Feb. 16, 2022
- Vol. 20, Issue 4, 041301 (2022)
Lasers, Optical Amplifiers, and Laser Optics
Highly integrated photonic crystal bandedge lasers monolithically grown on Si substrates | On the Cover
Yaoran Huang, Taojie Zhou, Mingchu Tang, Guohong Xiang, Haochuan Li, Mickael Martin, Thierry Baron, Siming Chen, Huiyun Liu, and Zhaoyu Zhang
Monolithic integration of III-V lasers with small footprint, good coherence, and low power consumption based on a CMOS-compatible Si substrate have been known as an efficient route towards high-density optical interconnects in the photonic integrated circuits. However, the material dissimilarities between Si and III-V materials limit the performance of monolithic microlasers. Here, under the pumping condition of a continuous-wave 632.8 nm He–Ne gas laser at room temperature, we achieved an InAs/GaAs quantum dot photonic crystal bandedge laser, which is directly grown on an on-axis Si (001) substrate, which provides a feasible route towards a low-cost and large-scale integration method for light sources on the Si platform.Monolithic integration of III-V lasers with small footprint, good coherence, and low power consumption based on a CMOS-compatible Si substrate have been known as an efficient route towards high-density optical interconnects in the photonic integrated circuits. However, the material dissimilarities between Si and III-V materials limit the performance of monolithic microlasers. Here, under the pumping condition of a continuous-wave 632.8 nm He–Ne gas laser at room temperature, we achieved an InAs/GaAs quantum dot photonic crystal bandedge laser, which is directly grown on an on-axis Si (001) substrate, which provides a feasible route towards a low-cost and large-scale integration method for light sources on the Si platform..
Chinese Optics Letters
- Publication Date: Feb. 16, 2022
- Vol. 20, Issue 4, 041401 (2022)
Single-frequency Er:YAG ceramic pulsed laser with frequency stability close to 100 kHz
Chaoyong Chen, Chunqing Gao, Huixing Dai, and Qing Wang
A single-frequency 1645 nm pulsed laser with frequency stability close to 100 kHz was demonstrated. The laser oscillator is injection-seeded by a single-frequency narrow linewidth Er:Y3Al5O12 (Er:YAG) nonplanar ring oscillator and frequency stabilized by the modified Pound–Drever–Hall method. The pulse repetition rate can be set from 100 to 500 Hz with the frequency stability from 82.72 kHz to 134.44 kHz and pulse energy from 9.84 mJ to 19.55 mJ. To our knowledge, this is the best frequency stability of a single-frequency pulsed laser with injection-seeding.A single-frequency 1645 nm pulsed laser with frequency stability close to 100 kHz was demonstrated. The laser oscillator is injection-seeded by a single-frequency narrow linewidth
Chinese Optics Letters
- Publication Date: Feb. 11, 2022
- Vol. 20, Issue 4, 041402 (2022)
Wavelength-tunable mode-locked Yb-doped fiber laser based on nonlinear Kerr beam clean-up effect
Shanchao Ma, Baofu Zhang, Qiurun He, Jing Guo, and Zhongxing Jiao
We demonstrate a novel approach to achieve wavelength-tunable ultrashort pulses from an all-fiber mode-locked laser with a saturable absorber based on the nonlinear Kerr beam clean-up effect. This saturable absorber was formed by a single-mode fiber spliced to a graded-index multimode fiber, and its tunable band-pass filter effect is described by a numerical model. By adjusting the bending condition of the graded-index multimode fiber, the laser could produce dissipative soliton pulses with their central wavelength tunable from 1040 nm to 1063 nm. The pulse duration of the output laser could be compressed externally to 791 fs, and the signal to noise ratio of its radio frequency spectrum was measured to be 75.5 dB.We demonstrate a novel approach to achieve wavelength-tunable ultrashort pulses from an all-fiber mode-locked laser with a saturable absorber based on the nonlinear Kerr beam clean-up effect. This saturable absorber was formed by a single-mode fiber spliced to a graded-index multimode fiber, and its tunable band-pass filter effect is described by a numerical model. By adjusting the bending condition of the graded-index multimode fiber, the laser could produce dissipative soliton pulses with their central wavelength tunable from 1040 nm to 1063 nm. The pulse duration of the output laser could be compressed externally to 791 fs, and the signal to noise ratio of its radio frequency spectrum was measured to be 75.5 dB..
Chinese Optics Letters
- Publication Date: Feb. 11, 2022
- Vol. 20, Issue 4, 041403 (2022)
Micro-spot-welding of copper sheets with an IR vortex beam
Chenyang Wang, Feng Wang, Yingxiong Qin, Fangwei Wang, and Xiao Yuan
Copper welding with an infrared (IR) Gaussian laser beam usually shows obvious instability, spatters, and worse surface morphology due to the Gaussian distribution, temperature-dependent IR absorption, and high thermal conductivity in copper. In this paper, the IR quasi-continuous-wave Gaussian beam was converted into a vortex ring beam with a phase-plate and then applied to the micro-spot-welding of copper sheets. The welding with the vortex beam demonstrated a significantly improved welding performance, smoother surface morphology, and higher welding stability. Besides, no spatters appeared in the welding process.Copper welding with an infrared (IR) Gaussian laser beam usually shows obvious instability, spatters, and worse surface morphology due to the Gaussian distribution, temperature-dependent IR absorption, and high thermal conductivity in copper. In this paper, the IR quasi-continuous-wave Gaussian beam was converted into a vortex ring beam with a phase-plate and then applied to the micro-spot-welding of copper sheets. The welding with the vortex beam demonstrated a significantly improved welding performance, smoother surface morphology, and higher welding stability. Besides, no spatters appeared in the welding process..
Chinese Optics Letters
- Publication Date: Mar. 09, 2022
- Vol. 20, Issue 4, 041404 (2022)
Direct generation of a stable multi-beam pulsed 355 nm UV laser based on a micro-lens array
Jiao Wei, Pixian Jin, Xuechen Cao, Jing Su, Huadong Lu, and Kunchi Peng
Multi-beam laser processing is a very popular method to improve processing efficiency. For this purpose, a compact and stable multi-beam pulsed 355 nm ultraviolet (UV) laser based on a micro-lens array (MLA) is presented in this Letter. It is worth noting that the MLA is employed to act as the spatial splitter as well as the coupling lens. With assistance of the MLA, the 1064 nm laser and 532 nm laser are divided into four sub-beams and focused at different areas of the third-harmonic generation (THG) crystal. As a result, the multi-beam pulsed 355 nm UV laser is successfully generated inside the THG crystal. The measured pulse widths of four sub-beams are shorter than 9 ns. Especially, the generated four sub-beams have good long-term power stability benefitting from the employed MLA. We believe that the generated stable multi-beam 355 nm UV laser can meet the requirement of high-efficiency laser processing, and the presented method can also pave the way to generate stable and long-lived multi-beam UV lasers.Multi-beam laser processing is a very popular method to improve processing efficiency. For this purpose, a compact and stable multi-beam pulsed 355 nm ultraviolet (UV) laser based on a micro-lens array (MLA) is presented in this Letter. It is worth noting that the MLA is employed to act as the spatial splitter as well as the coupling lens. With assistance of the MLA, the 1064 nm laser and 532 nm laser are divided into four sub-beams and focused at different areas of the third-harmonic generation (THG) crystal. As a result, the multi-beam pulsed 355 nm UV laser is successfully generated inside the THG crystal. The measured pulse widths of four sub-beams are shorter than 9 ns. Especially, the generated four sub-beams have good long-term power stability benefitting from the employed MLA. We believe that the generated stable multi-beam 355 nm UV laser can meet the requirement of high-efficiency laser processing, and the presented method can also pave the way to generate stable and long-lived multi-beam UV lasers..
Chinese Optics Letters
- Publication Date: Mar. 09, 2022
- Vol. 20, Issue 4, 041405 (2022)
Light-matter Interaction
Femtosecond-laser-induced backward transfer of fluorinated ethylene propylene for fabrication of “lotus effect” surfaces
Kongyu Lou, Jing Qian, Xiaohan Yu, Zhaoyuan Xia, Danyang Shen, Guande Wang, and Quan-Zhong Zhao
“Lotus effect” glass surfaces with fluorinated ethylene propylene were successfully fabricated by using a femtosecond laser-induced backward transfer (LIBT) method. By space-selectively modifying both the surface morphology and surface chemistry in a single step, LIBT provides a convenient and flexible route to fabricate superhydrophobic surfaces with ultralow adhesion. A systematic mechanism responsible for the anisotropic wetting behaviors and adhesion modulation was proposed with a combination of the Cassie and Wenzel models. X-ray photoelectron spectroscopy revealed that oxidation and defluorination were induced by laser radiation. LIBT is proved to be a promising method for programmable manipulations of functional surfaces with diverse wettability.“Lotus effect” glass surfaces with fluorinated ethylene propylene were successfully fabricated by using a femtosecond laser-induced backward transfer (LIBT) method. By space-selectively modifying both the surface morphology and surface chemistry in a single step, LIBT provides a convenient and flexible route to fabricate superhydrophobic surfaces with ultralow adhesion. A systematic mechanism responsible for the anisotropic wetting behaviors and adhesion modulation was proposed with a combination of the Cassie and Wenzel models. X-ray photoelectron spectroscopy revealed that oxidation and defluorination were induced by laser radiation. LIBT is proved to be a promising method for programmable manipulations of functional surfaces with diverse wettability..
Chinese Optics Letters
- Publication Date: Feb. 18, 2022
- Vol. 20, Issue 4, 043801 (2022)
Nanophotonics, Metamaterials, and Plasmonics
Manipulation of polarization conversion and multiplexing via all-silicon phase-modulated metasurfaces
Zhen Yue, Jitao Li, Chenglong Zheng, Jie Li, Mingyang Chen, Xuanruo Hao, Hang Xu, Qi Wang, Yating Zhang, and Jianquan Yao
Phase-modulated metasurfaces that can implement the independent manipulation of co- and cross-polarized output waves under circularly polarized (CP) incidence have been proposed. With this, we introduce one particular metasurface composed of meta-atoms with a phase difference of 2π/3 to generate specific elliptically polarized waves under various polarized incidences. Furthermore, a metasurface composed of these above meta-atoms and the meta-atoms with a phase difference of π/3 arranged in a certain rule can realize polarization conversion function between linearly polarized and CP states. The designs shed new light on multifarious optical devices and may further promote the development of metasurface polarization optics.Phase-modulated metasurfaces that can implement the independent manipulation of co- and cross-polarized output waves under circularly polarized (CP) incidence have been proposed. With this, we introduce one particular metasurface composed of meta-atoms with a phase difference of
Chinese Optics Letters
- Publication Date: Feb. 15, 2022
- Vol. 20, Issue 4, 043601 (2022)
Nonlinear Optics
Narrow-linewidth BaGa4Se7 optical parametric oscillator
Jintian Bian, Hui Kong, Qing Ye, Jiyong Yao, Lei Guo, and Xiaoquan Sun
The linewidth of the BaGa4Se7 (BGSe) optical parametric oscillator (OPO) was narrowed for the first time, to the best of our knowledge, by inserting a Fabry–Perot (FP) etalon into an L-shaped cavity. When a 15 mm long BGSe (56.3°, 0°) was pumped by a 1064 nm laser, the peak wavelength was ∼3529 nm, and the linewidth was 4.53 nm (3.64 cm-1) under type I phase matching. After inserting a 350 µm thick FP etalon, the linewidth was decreased to 1.27–2.05 nm. When the tilt angle of the etalon was 2.34°, the linewidth was 2.05 nm (1.65 cm-1), and the peak wavelength was still ∼3529 nm. When the tilt angle of the etalon was 3.90°, the peak wavelength was 3534.9 nm, and the linewidth was 1.27 nm (1.02 cm-1), which was the narrowest linewidth of a BGSe OPO, to the best of our knowledge. The beam quality was also improved after inserting the FP etalon.The linewidth of the
Chinese Optics Letters
- Publication Date: Feb. 14, 2022
- Vol. 20, Issue 4, 041901 (2022)
Magnetic-field-induced deflection of nonlocal light bullets in a Rydberg atomic gas
Xiujia Dong, Yao Ding, Zhengyang Bai, and Guoxiang Huang
Light bullets (LBs) are localized nonlinear waves propagating in high spatial dimensions. Finding stable LBs and realizing their control are desirable due to the interesting physics and potential applications. Here, we show that nonlocal LBs generated in a cold Rydberg atomic gas via the balance among the dispersion, diffraction, and giant nonlocal Kerr nonlinearity contributed by long-range Rydberg-Rydberg interaction can be actively manipulated by using a weak gradient magnetic field. Nonlocal LBs are generated by a balance among dispersion, diffraction, and large nonlocal Kerr nonlinearities contributed by long-range Rydberg-Rydberg interactions. Here, we find that active manipulation can be achieved by weak gradient magnetic fields in cold Rydberg atomic gases. Especially, the LBs may undergo significant Stern–Gerlach deflections, and their motion trajectories can be controlled by adjusting the magnetic-field gradient. The results reported here are helpful not only for understanding unique properties of LBs in nonlocal optical media but also for finding ways for precision measurements of magnetic fields.Light bullets (LBs) are localized nonlinear waves propagating in high spatial dimensions. Finding stable LBs and realizing their control are desirable due to the interesting physics and potential applications. Here, we show that nonlocal LBs generated in a cold Rydberg atomic gas via the balance among the dispersion, diffraction, and giant nonlocal Kerr nonlinearity contributed by long-range Rydberg-Rydberg interaction can be actively manipulated by using a weak gradient magnetic field. Nonlocal LBs are generated by a balance among dispersion, diffraction, and large nonlocal Kerr nonlinearities contributed by long-range Rydberg-Rydberg interactions. Here, we find that active manipulation can be achieved by weak gradient magnetic fields in cold Rydberg atomic gases. Especially, the LBs may undergo significant Stern–Gerlach deflections, and their motion trajectories can be controlled by adjusting the magnetic-field gradient. The results reported here are helpful not only for understanding unique properties of LBs in nonlocal optical media but also for finding ways for precision measurements of magnetic fields..
Chinese Optics Letters
- Publication Date: Feb. 28, 2022
- Vol. 20, Issue 4, 041902 (2022)
Optical Design and Fabrication
Plasmon hybridization induced by quasi bound state in the continuum of graphene metasurfaces oriented for high-accuracy polarization-insensitive two-dimensional sensors
Xiuyu Wang, Jihong Xin, Qun Ren, Haocheng Cai, Jiaqi Han, Chengyi Tian, Pengcheng Zhang, Lijie Jiang, Zhihao Lan, Jianwei You, and Wei E. I. Sha
Plasmonics could provide compact and powerful solutions for manipulating light in deep-subwavelength dimensions, which is promising for a great range of nanophotonic technologies such as plasmonic rulers and sensors. However, the effective area of enhanced localized field induced by surface plasmon polaritons is typically restricted to the structural boundaries. In this work, we propose a method to generate high quality-factor extended electromagnetic fields via hybridizing the super-radiant state and the quasi bound state in the continuum of graphene metasurfaces. The coupling interaction involved operates as a three-level system with multiple sharp resonances immune to the polarization, which holds great promise for developing nanodevices with high sensing capacity in two dimensions.Plasmonics could provide compact and powerful solutions for manipulating light in deep-subwavelength dimensions, which is promising for a great range of nanophotonic technologies such as plasmonic rulers and sensors. However, the effective area of enhanced localized field induced by surface plasmon polaritons is typically restricted to the structural boundaries. In this work, we propose a method to generate high quality-factor extended electromagnetic fields via hybridizing the super-radiant state and the quasi bound state in the continuum of graphene metasurfaces. The coupling interaction involved operates as a three-level system with multiple sharp resonances immune to the polarization, which holds great promise for developing nanodevices with high sensing capacity in two dimensions..
Chinese Optics Letters
- Publication Date: Mar. 10, 2022
- Vol. 20, Issue 4, 042201 (2022)
Optoelectronics
Nonlinear coded nonuniform superposition QAM by trellis-coding for MISO system in visible light communication
Zengyi Xu, Wenqing Niu, Jianyang Shi, and Nan Chi
In this paper, we propose a 36-quadrature amplitude modulation (QAM) superposition modulation technique that is featured with uneven symbol probability by nonlinear precoding, named nonlinear coded nonuniform superposition (NCNS) QAM. Its aim is to alleviate the nonlinearity effect caused by high instantaneous power in multi-input single-output (MISO) visible light communication (VLC) system, with an uneven probabilistic-shaped constellation. The transmitter includes two LEDs to send signals independently, and the receiver uses a photo detector to receive the superposed QAM signal. The experiment results show that NCNS has a better robustness against nonlinearity than pulse amplitude modulation 4, approximately gaining a 16% increase in maximum usable peak-to-peak voltage and a 33% enlargement in dynamic range area. It is a simple but effective approach to solve the bandwidth limits related to signal power and hopefully be applied in large power VLC systems such as underwater VLC, or to improve the robustness against power fluctuation.In this paper, we propose a 36-quadrature amplitude modulation (QAM) superposition modulation technique that is featured with uneven symbol probability by nonlinear precoding, named nonlinear coded nonuniform superposition (NCNS) QAM. Its aim is to alleviate the nonlinearity effect caused by high instantaneous power in multi-input single-output (MISO) visible light communication (VLC) system, with an uneven probabilistic-shaped constellation. The transmitter includes two LEDs to send signals independently, and the receiver uses a photo detector to receive the superposed QAM signal. The experiment results show that NCNS has a better robustness against nonlinearity than pulse amplitude modulation 4, approximately gaining a 16% increase in maximum usable peak-to-peak voltage and a 33% enlargement in dynamic range area. It is a simple but effective approach to solve the bandwidth limits related to signal power and hopefully be applied in large power VLC systems such as underwater VLC, or to improve the robustness against power fluctuation..
Chinese Optics Letters
- Publication Date: Feb. 18, 2022
- Vol. 20, Issue 4, 042501 (2022)
Ultrafast Optics and Attosecond/High-field Physics
Spintronic terahertz emitter with integrated electromagnetic control
Yunqing Jiang, Xiaoqiang Zhang, Yongshan Liu, Pierre Vallobra, Sylvain Eimer, Fan Zhang, Yinchang Du, Fengguang Liu, Yong Xu, and Weisheng Zhao
Spintronic thin films are considered as one of the promising terahertz (THz) source candidates, owing to their high performance and low cost. Much effort has been made to achieve spintronic THz sources with broadband and high conversion efficiency. However, the development of spintronic THz emitters with good compatibility, low cost, and miniaturized technology still faces many challenges. Therefore, it is urgent to extend commercial and portable spintronic THz emitters to satisfy many practical applications. Herein, we design a new generation of spintronic THz emitters composed of an alternating electromagnet and a miniaturized electronic controller. Not only can this new type of spintronic THz emitter largely simplify the ancillary equipment for spintronic sources, it also has a twice larger THz signal compared to the traditional THz time-domain spectroscopy systems with a mechanical chopper. Experimental results and theoretical calculations for electromagnetic coils show that our design can stably generate THz signals that are independent of the frequency and magnetic field of alternating signals. As the spin thin film is optimized, a magnetic field as low as 75 G satisfies the requirement for high performance THz emission. Hence, not only is the efficiency of the pump power enhanced, but also the driving current in the electromagnet is decreased. We believe that it has a wide range of applications and profound implications in THz technology based on spintronic emitters in the future.Spintronic thin films are considered as one of the promising terahertz (THz) source candidates, owing to their high performance and low cost. Much effort has been made to achieve spintronic THz sources with broadband and high conversion efficiency. However, the development of spintronic THz emitters with good compatibility, low cost, and miniaturized technology still faces many challenges. Therefore, it is urgent to extend commercial and portable spintronic THz emitters to satisfy many practical applications. Herein, we design a new generation of spintronic THz emitters composed of an alternating electromagnet and a miniaturized electronic controller. Not only can this new type of spintronic THz emitter largely simplify the ancillary equipment for spintronic sources, it also has a twice larger THz signal compared to the traditional THz time-domain spectroscopy systems with a mechanical chopper. Experimental results and theoretical calculations for electromagnetic coils show that our design can stably generate THz signals that are independent of the frequency and magnetic field of alternating signals. As the spin thin film is optimized, a magnetic field as low as 75 G satisfies the requirement for high performance THz emission. Hence, not only is the efficiency of the pump power enhanced, but also the driving current in the electromagnet is decreased. We believe that it has a wide range of applications and profound implications in THz technology based on spintronic emitters in the future..
Chinese Optics Letters
- Publication Date: Mar. 09, 2022
- Vol. 20, Issue 4, 043201 (2022)
About the Cover
Monolithic integration of III-V lasers with small footprint, good coherence and low power consumption based on CMOS-compatible Si substrate has been known as an ef?cient route towards high-density optical interconnects in the photonic integrated circuits. However, the material dissimilarities between Si and III-V materials limit the performance of monolithic microlasers. Here, under the pumping condition of continuous-wave 632.8nm He-Ne gas laser at room-temperature, we achieved InAs/GaAs quantum dot photonic crystal band-edge laser, with the crystal directly grown on on-axis Si (001) substrate. This provides a feasible route towards a low-cost and large-scale integration method for light sources on the Si platform.
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