We investigate the resonance fluorescence spectrum of an atomic three-level ladder system driven by two laser fields. We show that such a system emulates to a large degree a V-type atom with parallel dipole moments-th...We investigate the resonance fluorescence spectrum of an atomic three-level ladder system driven by two laser fields. We show that such a system emulates to a large degree a V-type atom with parallel dipole moments-the latter being a system that exhibits spontaneously generated coherence and can display ultrasharp spectral lines. We find a suitable energy scheme in a SSRb atom and experimentally observe the narrowing of the central peak in a rubidium atomic beam. The corresponding spectrum can convindngiy demonstrate the existence of spontaneously generated coherence.展开更多
We present a quantum-theoretical treatment of cavity linewidth narrowing with intracavity electromagnetically in- duced transparency （EIT）. By means of intracavity EIT, the photons in the cavity are in the form of c...We present a quantum-theoretical treatment of cavity linewidth narrowing with intracavity electromagnetically in- duced transparency （EIT）. By means of intracavity EIT, the photons in the cavity are in the form of cavity polaritons： bright-state polariton and dark-state polariton. Strong coupling of the bright-state polariton to the excited state induces an effect known as vacuum Rabi splitting, whereas the dark-state polariton decoupled from the excited state induces a narrow cavity transmission window. Our analysis would provide a quantum theory of linewidth narrowing with a quantum field pulse.展开更多
This study analyzes the linewidth narrowing characteristics of free-space-running Brillouin lasers and investigates the approaches to achieve linewidth compression and power enhancement simultaneously.The results show...This study analyzes the linewidth narrowing characteristics of free-space-running Brillouin lasers and investigates the approaches to achieve linewidth compression and power enhancement simultaneously.The results show that the Stokes linewidth behavior in a free-space-running Brillouin laser cavity is determined by the phase diffusion of the pump and the technical noise of the system.Experimentally,a Stokes light output with a power of 22.5 W and a linewidth of 3.2 kHz was obtained at a coupling mirror reflectivity of 96%,which is nearly 2.5 times compressed compared with the linewidth of the pump(7.36 kHz).In addition,the theorical analysis shows that at a pump power of 60Wand a coupling mirror reflectivity of 96%,a Stokes output with a linewidth of 1.6 kHz and up to 80%optical conversion efficiency can be achieved by reducing the insertion loss of the intracavity.This study provides a promising technical route to achieve high-power ultra-narrow linewidth special wavelength laser radiations.展开更多
Two Nd：YAG lasers operating at 1064 nm are separately servo-locked to two vertically mounted ultra-stable cavities. The optical heterodyne beat between two cavity-stabilized lasers shows that the linewidth of each la...Two Nd：YAG lasers operating at 1064 nm are separately servo-locked to two vertically mounted ultra-stable cavities. The optical heterodyne beat between two cavity-stabilized lasers shows that the linewidth of each laser reaches 2 Hz and the average frequency drift reduces to less than 1 Hz/s.展开更多
Interference filter-stabilized external cavity diode lasers （ECDLs） have properties of simple configurations, high sta- bilities, and narrow linewidths. However, the interference filter used in common ECDL designs r...Interference filter-stabilized external cavity diode lasers （ECDLs） have properties of simple configurations, high sta- bilities, and narrow linewidths. However, the interference filter used in common ECDL designs requires an ultra-narrow bandwidth （about 0.3 nm） to achieve mode selection, that is considerably expensive and not yet available for a wide range of wavelengths. In this paper, a robust ECDL using an available broad bandwidth （about 4 nm） interference filter as the wavelength discriminator is constructed and tested. The ECDL demonstrated a narrow Lorentzian fitted linewidth of 95 kHz and a spectral purity of 2.9 MHz. The long-term frequency stability of the ECDL reaches 5.59 x 10 12.展开更多
Narrow linewidth light source is a prerequisite for high-performance coherent optical communication and sensing.Waveguide-based external cavity narrow linewidth semiconductor lasers(WEC-NLSLs)have become a competitive...Narrow linewidth light source is a prerequisite for high-performance coherent optical communication and sensing.Waveguide-based external cavity narrow linewidth semiconductor lasers(WEC-NLSLs)have become a competitive and attractive candidate for many coherent applications due to their small size,volume,low energy consumption,low cost and the ability to integrate with other optical components.In this paper,we present an overview of WEC-NLSLs from their required technologies to the state-of-the-art progress.Moreover,we highlight the common problems occurring to current WEC-NLSLs and show the possible approaches to resolving the issues.Finally,we present the possible development directions for the next phase and hope this review will be beneficial to the advancements of WEC-NLSLs.展开更多
A 60-mW solid-state deep ultraviolet(DUV)laser at 193 nm with narrow linewidth is obtained with two stages of sum frequency generation in LBO crystals.The pump lasers,at 258 and 1553 nm,are derived from a homemade Yb-...A 60-mW solid-state deep ultraviolet(DUV)laser at 193 nm with narrow linewidth is obtained with two stages of sum frequency generation in LBO crystals.The pump lasers,at 258 and 1553 nm,are derived from a homemade Yb-hybrid laser employing fourth-harmonic generation and Er-doped fiber laser,respectively.The Yb-hybrid laser,finally,is power scaling by a 2 mm×2 mm×30 mm Yb:YAG bulk crystal.Accompanied by the generated 220-mW DUV laser at 221 nm,the 193-nm laser delivers an average power of 60 mW with a pulse duration of 4.6 ns,a repetition rate of 6 kHz,and a linewidth of∼640 MHz.To the best of our knowledge,this is the highest power of 193-and 221-nm laser generated by an LBO crystal ever reported as well as the narrowest linewidth of 193-nm laser by it.Remarkably,the conversion efficiency reaches 27%for 221 to 193 nm and 3%for 258 to 193 nm,which are the highest efficiency values reported to date.We demonstrate the huge potential of LBO crystals for producing hundreds of milliwatt or even watt level 193-nm laser,which also paves a brand-new way to generate other DUV laser wavelengths.展开更多
Quantum cascade lasers(QCLs) have broad application potentials in infrared countermeasure system,free-space optical communication and trace gas detection.Compared with traditional Fabry-Pérot(FP) cavity and exter...Quantum cascade lasers(QCLs) have broad application potentials in infrared countermeasure system,free-space optical communication and trace gas detection.Compared with traditional Fabry-Pérot(FP) cavity and external cavity,distributed feedback quantum cascade lasers(DFB-QCLs) can obtain narrower laser linewidth and higher integration.In this paper,the structure design,numerical simulation and optimization of the Bragg grating of DFB-QCLs are carried out to obtain the transmission spectrum with central wavelength at 4.6 μm.We analyze the relationship among the structure parameters,the central wavelength shift and transmission efficiency using coupled-wave theory and finite-difference time-domain(FDTD) method.It is shown that the increase in the number of grating periods enhances the capabilities of mode selectivity,while the grating length of a single period adjustment directly determines the Bragg wavelength.Additionally,variations in etching depth and duty cycle lead to blue and red shifts in the central wavelength,respectively.Based on the numerical simulation results,the optimized design parameters for the upper buffer layer and the upper cladding grating are proposed,which gives an optional scheme for component fabrication and performance improvement in the future.展开更多
Ultra-high spectral purity lasers are of considerable research interests in numerous fields such as coherent optical communication,microwave photonics,distributed optical fiber sensing,gravitational wave detection,opt...Ultra-high spectral purity lasers are of considerable research interests in numerous fields such as coherent optical communication,microwave photonics,distributed optical fiber sensing,gravitational wave detection,optical clock,and so on.Herein,to deeply purify laser spectrum with compact size under normal condition,we propose a novel and practical idea to effectively suppress the spontaneous radiation of the laser cavity through weak external distributed perturbation.Subsequently,a laser configuration consisting of a main lasing cavity and an external distributed feedback cavity is proposed.The feedback signal with continuous spatio-temporal phase transition controlled by a distributed feedback structure is injected into the main cavity,which can deeply suppress the coupling rate from the spontaneous radiation to the stimulated emission and extremely purify the laser spectrum.Eventually,an ultra-narrow linewidth on-chip laser system with a side mode suppression ratio greater than 80 dB,an output linewidth of 10 Hz,and a relative intensity noise less than-150 dB/Hz is successfully obtained under normal conditions.The proposed concept in this work provides a new perspective for extreme regulation of laser parameters by using weak external distributed perturbation,which can be valid for various gain-type lasers with wide wavelength bands.展开更多
This paper investigates the influences of a semiconductor laser with narrow linewidth on a fibre-optic distributed disturbance sensor based on Mach-Zehnder interferometer. It establishes an effective numerical model t...This paper investigates the influences of a semiconductor laser with narrow linewidth on a fibre-optic distributed disturbance sensor based on Mach-Zehnder interferometer. It establishes an effective numerical model to describe the noises and linewidth of a semiconductor laser, taking into account their correlations. Simulation shows that frequency noise has great influences on location errors and their relationship is numerically investigated. Accordingly, there is need to determine the linewidth of the laser less than a threshold and obtain the least location errors. Furthermore, experiments are performed by a sensor prototype using three semiconductor lasers with different linewidths, respectively, with polarization maintaining optical fibres and couplers to eliminate the polarization induced noises and fading. The agreement of simulation with experimental results means that the proposed numerical model can make a comprehensive description of the noise behaviour of a semiconductor laser. The conclusion is useful for choosing a laser source for fibre-optic distributed disturbance sensor to achieve optimized location accuracy. What is more, the proposed numerical model can be widely used for analysing influences of semiconductor lasers on other sensing, communication and optical signal processing systems.展开更多
A laser at 578 nm is phase-locked to an optical frequency comb（OFC） which is optically referenced to a subhertzlinewidth laser at 1064 nm. Coherence is transferred from 1064 nm to 578 nm via the OFC. By comparing wi...A laser at 578 nm is phase-locked to an optical frequency comb（OFC） which is optically referenced to a subhertzlinewidth laser at 1064 nm. Coherence is transferred from 1064 nm to 578 nm via the OFC. By comparing with a cavitystabilized laser at 578 nm, the absolute linewidth of 1.1 Hz and the fractional frequency instability of 1.3 × 10^-15 at an averaging time of 1 s for each laser at 578 nm have been determined, which is limited by the performance of the reference laser for the OFC.展开更多
A widely-wavelength-tunable Brillouin fiber laser(BFL)with improved optical signal-to-noise ratio(OSNR)based on parity-time(PT)symmetric and saturable absorption(SA)effect is present.This novel BFL realizes PT symmetr...A widely-wavelength-tunable Brillouin fiber laser(BFL)with improved optical signal-to-noise ratio(OSNR)based on parity-time(PT)symmetric and saturable absorption(SA)effect is present.This novel BFL realizes PT symmetry and SA effect through polarization-maintaining erbium-doped fiber(PM-EDF)Sagnac loop,which is composed of a PM-EDF,a coupler and two polarization controllers(PCs).By using the inherent birefringence characteristic of PM-EDF,two feedback loops in orthogonal polarization state are formed when the Strokes signal in injected.One of these loops provides gain in the clockwise direction with in the Sagnac loop,while the other loop generates loss in the counterclockwise direction.By adjusting the PCs to control the polarization state of the PM-EDF,a single-longitudinal-mode(SLM)BFL can be achieved,as the PT symmetry is broken when the SA participating stimulated Brillouin scattering(SBS)gain and loss are well-matched and the gain surpasses the coupling coefficient.Compared to previous BFLs,the proposed BFL has a more streamlined structure and a wider wavelength tunable range,at the same time,it is not being limited by the bandwidth of the erbium-doped fiber amplifier while still maintaining narrow linewidth SLM output.Additionally,thanks to SA effect of the PM-EDF,the PT symmetric SBS gain contract is enhanced,resulting in a higher optical signal-to-noise(OSNR).The experimental results show that the laser has a wide tunable range of 1526.088 nm to 1565.498 nm,an improved OSNR of 77 dB,and a fine linewidth as small as 140.5 Hz.展开更多
We have studied the probe gain via a double-Λ atomic system with a pair of closely lying lower levels in the presence of two probe and two coherent pump fields. The inversionless gain can be realized by using nondege...We have studied the probe gain via a double-Λ atomic system with a pair of closely lying lower levels in the presence of two probe and two coherent pump fields. The inversionless gain can be realized by using nondegenerate four-wave mixing under the condition of spontaneously generated coherence（SGC） owing to near-degenerate lower levels. Note that by using SGC, two probe fields can be amplified with more remarkable amplitudes, and the gain spectra of an extremely narrow linewidth can be obtained. Last but not least, our results show that the probe gain is quite sensitive to relative phases due to the SGC presence which allows one to modulate the gain spectra periodically by phase modulation, and can also be influenced by all laser field intensities and frequencies, and the angles between dipole elements.展开更多
In this paper, an injection-seeded nanosecond optical parametric generation (OPG) using BBO crystal, which combines relatively low thresholds with a simple and compact configuration, was demonstrated. By seeding exter...In this paper, an injection-seeded nanosecond optical parametric generation (OPG) using BBO crystal, which combines relatively low thresholds with a simple and compact configuration, was demonstrated. By seeding externally with distributed feedback (DFB) diode laser at 1313 nm wavelength, pumped by 355 nm laser pulse, the maximum blue laser output power of 1.36 W at a rate of 100 Hz and with linewidth less than 0.13 nm were obtained, and the maximum optical to optical conversion efficiency was to 21.2%.展开更多
Ytterbium ion(Yb^(3+))-doped lasers are widely used in precision machining and precision measurement fields because of their high efficiency and high power,which are primarily based on solid-state lasers and fiber las...Ytterbium ion(Yb^(3+))-doped lasers are widely used in precision machining and precision measurement fields because of their high efficiency and high power,which are primarily based on solid-state lasers and fiber lasers.Here,we demonstrate an on-chip Yb^(3+)-doped thin-film lithium niobate(Yb:TFLN)Fabry-Perot microcavity laser.We achieve single-frequency laser operation at 1030 and 1060 nm with a side-mode suppression ratio above 30 dB,an emission linewidth below 40 pm,and an output power up to 1.5 mW at 1060 nm and 0.3 mW at 1030 nm.In addition,using the electro-optic effect of lithium niobate,we achieve a laser tuning efficiency of 4 pm/V.This work opens the path to on-chip high-power and mode-locked ultrafast laser output.展开更多
Stimulated Brillouin scattering(SBS)-induced mode distortion(MD)in high power narrow linewidth fiber amplifiers has been implemented,and the origin has been investigated from the aspect of the evolution of the optical...Stimulated Brillouin scattering(SBS)-induced mode distortion(MD)in high power narrow linewidth fiber amplifiers has been implemented,and the origin has been investigated from the aspect of the evolution of the optical spectrum,spatial beam profiles,and temporal-frequency domain characteristics.展开更多
In this manuscript, we demonstrate high-power, narrow-linewidth linearly polarized fiber laser with excellent beam quality through compact one-stage amplification scheme. By employing a single-mode–multimode–single-...In this manuscript, we demonstrate high-power, narrow-linewidth linearly polarized fiber laser with excellent beam quality through compact one-stage amplification scheme. By employing a single-mode–multimode–single-mode structure seed laser, a linearly polarized Yb-doped fiber laser with narrow linewidth and high output power is achieved.This laser, when used as a master oscillator, can be capable of suppressing the ASE in the process of power amplification.Thus, only one-stage amplification structure is used to scale up the laser power, and linearly polarized output with a polarization extinction ration of 14 d B, a narrow linewidth of 0.3 nm and an output power of 1018 W are achieved.Moreover, due to the good beam quality of seed laser and the well-designed amplifier stage, the beam quality of the output laser is near-diffraction-limited with M_x^2 ~1.18 and M_y^2 ~ 1.24 at the maximum power, and without mode instability occurring.展开更多
In this work,an all-fiberized and narrow-linewidth fiber amplifier with record output power and near-diffraction-limited beam quality is presented.Up to 6.12 kW fiber laser with the conversion efficiency of approximat...In this work,an all-fiberized and narrow-linewidth fiber amplifier with record output power and near-diffraction-limited beam quality is presented.Up to 6.12 kW fiber laser with the conversion efficiency of approximately 78.8%is achieved through the fiber amplifier based on a conventional step-index active fiber.At the maximum output power,the 3 dB spectral linewidth is approximately 0.86 nm and the beam quality factor is M_(x)^(2)=1.43,M_(y)^(2)=1.36.We have also measured and compared the output properties of the fiber amplifier employing different pumping schemes.Notably,the practical power limit of the fiber amplifier could be estimated through the maximum output powers of the fiber amplifier employing unidirectional pumping schemes.Overall,this work could provide a good reference for the optimal design and potential exploration of high-power narrow-linewidth fiber laser systems.展开更多
The linewidth of the BaGa_(4)Se_(7)(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 BG...The linewidth of the BaGa_(4)Se_(7)(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 350μm 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.展开更多
In this research,the highly efficient external cavity feedback technology based on volume Bragg grating(VBG)is studied.By using the structure of a fast axis collimating lens,the beam transformation system,a slow axis ...In this research,the highly efficient external cavity feedback technology based on volume Bragg grating(VBG)is studied.By using the structure of a fast axis collimating lens,the beam transformation system,a slow axis collimating lens,and VBG,the divergence angle of the fast and slow axes of the diode laser incident on the VBG is reduced effectively,and the feedback efficiency of the external cavity is improved.Combined with beam combining technology,fiber coupling technology,and precision temperature control technology,a high-power and narrow-linewidth diode laser pump source of kilowatt class is realized for alkali metal vapor laser pumping.The core diameter of the optical fiber is 1000μm,the numerical aperture is 0.22,the output power from the fiber is 1013 W,the fiber coupling efficiency exceeds 89%,and the external cavity efficiency exceeds 91%.The central wavelength is 852.052 nm(in air),which is tunable from 851.956 nm to 852.152 nm,and the spectral linewidth is 0.167 nm.Research results can be used for cesium alkali metal vapor laser pumping.展开更多
基金Project supported by the National Basic Research Program of China (Grant No. 2011CB921603)the National Natural Science Foundation of China (Grant Nos. 11074097,10904048,10974071,and 11004080)
文摘We investigate the resonance fluorescence spectrum of an atomic three-level ladder system driven by two laser fields. We show that such a system emulates to a large degree a V-type atom with parallel dipole moments-the latter being a system that exhibits spontaneously generated coherence and can display ultrasharp spectral lines. We find a suitable energy scheme in a SSRb atom and experimentally observe the narrowing of the central peak in a rubidium atomic beam. The corresponding spectrum can convindngiy demonstrate the existence of spontaneously generated coherence.
基金supported by the National Natural Science Foundation of China(Grants Nos.11204080,11274112,91321101,and 61275215)the Fundamental Research Fund for the Central Universities of China(Grants No.WM1313003)
文摘We present a quantum-theoretical treatment of cavity linewidth narrowing with intracavity electromagnetically in- duced transparency （EIT）. By means of intracavity EIT, the photons in the cavity are in the form of cavity polaritons： bright-state polariton and dark-state polariton. Strong coupling of the bright-state polariton to the excited state induces an effect known as vacuum Rabi splitting, whereas the dark-state polariton decoupled from the excited state induces a narrow cavity transmission window. Our analysis would provide a quantum theory of linewidth narrowing with a quantum field pulse.
基金the National Natural Science Foundation of China(No.61927815)the Natural Science Foundation of Tianjin City(Nos.22JCYBJC01100 and 20JCZDJC00430)+4 种基金the Shijiazhuang Overseas Talents Introduction Project(No.20230004)the Program of State Key Laboratory of Quantum Optics and Quantum Optics Devices(No.KF202201)Funds for Basic Scientific Research of Hebei University of Technology(No.JBKYTD2201)D.J.acknowledges the support from the Postgraduate Innovation Ability Training Program of Hebei Province(No.CXZZBS2021030)R.P.M.acknowledges the support from the Asian Office of Aerospace Research and Development(AOARD).
文摘This study analyzes the linewidth narrowing characteristics of free-space-running Brillouin lasers and investigates the approaches to achieve linewidth compression and power enhancement simultaneously.The results show that the Stokes linewidth behavior in a free-space-running Brillouin laser cavity is determined by the phase diffusion of the pump and the technical noise of the system.Experimentally,a Stokes light output with a power of 22.5 W and a linewidth of 3.2 kHz was obtained at a coupling mirror reflectivity of 96%,which is nearly 2.5 times compressed compared with the linewidth of the pump(7.36 kHz).In addition,the theorical analysis shows that at a pump power of 60Wand a coupling mirror reflectivity of 96%,a Stokes output with a linewidth of 1.6 kHz and up to 80%optical conversion efficiency can be achieved by reducing the insertion loss of the intracavity.This study provides a promising technical route to achieve high-power ultra-narrow linewidth special wavelength laser radiations.
基金Project supported by the National Natural Science Foundation of China (Grant No 60490280)the State Key Development for Basic Research Program of China (Grant Nos 2006CB806005 and 2006CB921104)+2 种基金the Science and Technology Commission of Shanghai Municipality, China (Grant Nos 06JC14026 and 07JC14019)Shanghai Pujiang Talent Program, China (Grant No 07PJ14038)the Program for Changjiang Scholars and Innovative Research Teams, China
文摘Two Nd：YAG lasers operating at 1064 nm are separately servo-locked to two vertically mounted ultra-stable cavities. The optical heterodyne beat between two cavity-stabilized lasers shows that the linewidth of each laser reaches 2 Hz and the average frequency drift reduces to less than 1 Hz/s.
基金Project supported by the Foundation of Based Technology of China(Grant No.YXBGD20151JL01)the National Natural Science Foundation of China(Grant Nos.61376049,61604007,11674016,61378058,61575008,and 61574011)+1 种基金the Natural Science Foundation of Beijing City,China(Grant Nos.4172009 and4152003)the Beijing Municipal Commission of Education of China(Grant Nos.PXM2017 014204 500034 and PXM2016 014204 500018)
文摘Interference filter-stabilized external cavity diode lasers （ECDLs） have properties of simple configurations, high sta- bilities, and narrow linewidths. However, the interference filter used in common ECDL designs requires an ultra-narrow bandwidth （about 0.3 nm） to achieve mode selection, that is considerably expensive and not yet available for a wide range of wavelengths. In this paper, a robust ECDL using an available broad bandwidth （about 4 nm） interference filter as the wavelength discriminator is constructed and tested. The ECDL demonstrated a narrow Lorentzian fitted linewidth of 95 kHz and a spectral purity of 2.9 MHz. The long-term frequency stability of the ECDL reaches 5.59 x 10 12.
基金Jiangsu Province Key R&D Program(Industry Prospect and Common Key Technologies)(No.BE2014083)Jiangxi Natural Science Foundation Project(No.2019ACBL20054)。
文摘Narrow linewidth light source is a prerequisite for high-performance coherent optical communication and sensing.Waveguide-based external cavity narrow linewidth semiconductor lasers(WEC-NLSLs)have become a competitive and attractive candidate for many coherent applications due to their small size,volume,low energy consumption,low cost and the ability to integrate with other optical components.In this paper,we present an overview of WEC-NLSLs from their required technologies to the state-of-the-art progress.Moreover,we highlight the common problems occurring to current WEC-NLSLs and show the possible approaches to resolving the issues.Finally,we present the possible development directions for the next phase and hope this review will be beneficial to the advancements of WEC-NLSLs.
基金supported by the Research Project of Aerospace Information Research Institute,Chinese Academy of Sciences (Grant Nos.E1Z1D101 and E2Z2D101)the Project of Chinese Academy of Sciences (Grant No.E33310030D)the Guangzhou Basic and Applied Basic Research Foundation (Grant Nos.2023A04J0336 and 2023A04J0021).
文摘A 60-mW solid-state deep ultraviolet(DUV)laser at 193 nm with narrow linewidth is obtained with two stages of sum frequency generation in LBO crystals.The pump lasers,at 258 and 1553 nm,are derived from a homemade Yb-hybrid laser employing fourth-harmonic generation and Er-doped fiber laser,respectively.The Yb-hybrid laser,finally,is power scaling by a 2 mm×2 mm×30 mm Yb:YAG bulk crystal.Accompanied by the generated 220-mW DUV laser at 221 nm,the 193-nm laser delivers an average power of 60 mW with a pulse duration of 4.6 ns,a repetition rate of 6 kHz,and a linewidth of∼640 MHz.To the best of our knowledge,this is the highest power of 193-and 221-nm laser generated by an LBO crystal ever reported as well as the narrowest linewidth of 193-nm laser by it.Remarkably,the conversion efficiency reaches 27%for 221 to 193 nm and 3%for 258 to 193 nm,which are the highest efficiency values reported to date.We demonstrate the huge potential of LBO crystals for producing hundreds of milliwatt or even watt level 193-nm laser,which also paves a brand-new way to generate other DUV laser wavelengths.
基金supported by the Scientific Research Project of Beijing Municipal Education Commission (No.KM202411232020)the Young Backbone Teacher Support Plan (No.YBT202408)the Scientific Researchof Beijing Information Science and Technology University (No.2023XJJ08)。
文摘Quantum cascade lasers(QCLs) have broad application potentials in infrared countermeasure system,free-space optical communication and trace gas detection.Compared with traditional Fabry-Pérot(FP) cavity and external cavity,distributed feedback quantum cascade lasers(DFB-QCLs) can obtain narrower laser linewidth and higher integration.In this paper,the structure design,numerical simulation and optimization of the Bragg grating of DFB-QCLs are carried out to obtain the transmission spectrum with central wavelength at 4.6 μm.We analyze the relationship among the structure parameters,the central wavelength shift and transmission efficiency using coupled-wave theory and finite-difference time-domain(FDTD) method.It is shown that the increase in the number of grating periods enhances the capabilities of mode selectivity,while the grating length of a single period adjustment directly determines the Bragg wavelength.Additionally,variations in etching depth and duty cycle lead to blue and red shifts in the central wavelength,respectively.Based on the numerical simulation results,the optimized design parameters for the upper buffer layer and the upper cladding grating are proposed,which gives an optional scheme for component fabrication and performance improvement in the future.
基金supported by the National Natural Science Foundation of China(NSFC)(61635004)the National Science Fund for Distinguished Young Scholars(61825501)the Chongqing Natural Science Foundation of Innovative Research Groups under Grant(CSTC2020JCYJ,CXTTX0005)。
文摘Ultra-high spectral purity lasers are of considerable research interests in numerous fields such as coherent optical communication,microwave photonics,distributed optical fiber sensing,gravitational wave detection,optical clock,and so on.Herein,to deeply purify laser spectrum with compact size under normal condition,we propose a novel and practical idea to effectively suppress the spontaneous radiation of the laser cavity through weak external distributed perturbation.Subsequently,a laser configuration consisting of a main lasing cavity and an external distributed feedback cavity is proposed.The feedback signal with continuous spatio-temporal phase transition controlled by a distributed feedback structure is injected into the main cavity,which can deeply suppress the coupling rate from the spontaneous radiation to the stimulated emission and extremely purify the laser spectrum.Eventually,an ultra-narrow linewidth on-chip laser system with a side mode suppression ratio greater than 80 dB,an output linewidth of 10 Hz,and a relative intensity noise less than-150 dB/Hz is successfully obtained under normal conditions.The proposed concept in this work provides a new perspective for extreme regulation of laser parameters by using weak external distributed perturbation,which can be valid for various gain-type lasers with wide wavelength bands.
文摘This paper investigates the influences of a semiconductor laser with narrow linewidth on a fibre-optic distributed disturbance sensor based on Mach-Zehnder interferometer. It establishes an effective numerical model to describe the noises and linewidth of a semiconductor laser, taking into account their correlations. Simulation shows that frequency noise has great influences on location errors and their relationship is numerically investigated. Accordingly, there is need to determine the linewidth of the laser less than a threshold and obtain the least location errors. Furthermore, experiments are performed by a sensor prototype using three semiconductor lasers with different linewidths, respectively, with polarization maintaining optical fibres and couplers to eliminate the polarization induced noises and fading. The agreement of simulation with experimental results means that the proposed numerical model can make a comprehensive description of the noise behaviour of a semiconductor laser. The conclusion is useful for choosing a laser source for fibre-optic distributed disturbance sensor to achieve optimized location accuracy. What is more, the proposed numerical model can be widely used for analysing influences of semiconductor lasers on other sensing, communication and optical signal processing systems.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11334002,11374102,11104077,and 11127405)the National Basic Research Program of China(Grant No.2012CB821302)
文摘A laser at 578 nm is phase-locked to an optical frequency comb（OFC） which is optically referenced to a subhertzlinewidth laser at 1064 nm. Coherence is transferred from 1064 nm to 578 nm via the OFC. By comparing with a cavitystabilized laser at 578 nm, the absolute linewidth of 1.1 Hz and the fractional frequency instability of 1.3 × 10^-15 at an averaging time of 1 s for each laser at 578 nm have been determined, which is limited by the performance of the reference laser for the OFC.
文摘A widely-wavelength-tunable Brillouin fiber laser(BFL)with improved optical signal-to-noise ratio(OSNR)based on parity-time(PT)symmetric and saturable absorption(SA)effect is present.This novel BFL realizes PT symmetry and SA effect through polarization-maintaining erbium-doped fiber(PM-EDF)Sagnac loop,which is composed of a PM-EDF,a coupler and two polarization controllers(PCs).By using the inherent birefringence characteristic of PM-EDF,two feedback loops in orthogonal polarization state are formed when the Strokes signal in injected.One of these loops provides gain in the clockwise direction with in the Sagnac loop,while the other loop generates loss in the counterclockwise direction.By adjusting the PCs to control the polarization state of the PM-EDF,a single-longitudinal-mode(SLM)BFL can be achieved,as the PT symmetry is broken when the SA participating stimulated Brillouin scattering(SBS)gain and loss are well-matched and the gain surpasses the coupling coefficient.Compared to previous BFLs,the proposed BFL has a more streamlined structure and a wider wavelength tunable range,at the same time,it is not being limited by the bandwidth of the erbium-doped fiber amplifier while still maintaining narrow linewidth SLM output.Additionally,thanks to SA effect of the PM-EDF,the PT symmetric SBS gain contract is enhanced,resulting in a higher optical signal-to-noise(OSNR).The experimental results show that the laser has a wide tunable range of 1526.088 nm to 1565.498 nm,an improved OSNR of 77 dB,and a fine linewidth as small as 140.5 Hz.
基金Project supported by the Natural Science Foundation of Hainan Province,China(Grant Nos.20151005,20151015,and 20161006)the National Natural Science Foundation of China(Grant Nos.11247005,51262007,11501153,and 41564006)+2 种基金the Postdoctoral Scientific Research Program of Jilin Province,China(Grant No.RB201330)the Project Sponsored by Science Research Foundation for Returned Overseas Chinese Scholarsthe Fundamental Research Funds for the Central Universities,China(Grant No.12QNJJ006)
文摘We have studied the probe gain via a double-Λ atomic system with a pair of closely lying lower levels in the presence of two probe and two coherent pump fields. The inversionless gain can be realized by using nondegenerate four-wave mixing under the condition of spontaneously generated coherence（SGC） owing to near-degenerate lower levels. Note that by using SGC, two probe fields can be amplified with more remarkable amplitudes, and the gain spectra of an extremely narrow linewidth can be obtained. Last but not least, our results show that the probe gain is quite sensitive to relative phases due to the SGC presence which allows one to modulate the gain spectra periodically by phase modulation, and can also be influenced by all laser field intensities and frequencies, and the angles between dipole elements.
文摘In this paper, an injection-seeded nanosecond optical parametric generation (OPG) using BBO crystal, which combines relatively low thresholds with a simple and compact configuration, was demonstrated. By seeding externally with distributed feedback (DFB) diode laser at 1313 nm wavelength, pumped by 355 nm laser pulse, the maximum blue laser output power of 1.36 W at a rate of 100 Hz and with linewidth less than 0.13 nm were obtained, and the maximum optical to optical conversion efficiency was to 21.2%.
基金National Key Research and Development Program of China(2023YFB4604600)National Natural Science Foundation of China(12274133,12334014,12192251,12134001,12474378,12404379)+1 种基金Innovation Program for Quantum Science and Technology(2021ZD0301403)Fundamental Research Funds for the Central Universities,Engineering Research Center for Nanophotonics&Advanced Instrument,Ministry of Education,East China Normal University(2023nmc005)。
文摘Ytterbium ion(Yb^(3+))-doped lasers are widely used in precision machining and precision measurement fields because of their high efficiency and high power,which are primarily based on solid-state lasers and fiber lasers.Here,we demonstrate an on-chip Yb^(3+)-doped thin-film lithium niobate(Yb:TFLN)Fabry-Perot microcavity laser.We achieve single-frequency laser operation at 1030 and 1060 nm with a side-mode suppression ratio above 30 dB,an emission linewidth below 40 pm,and an output power up to 1.5 mW at 1060 nm and 0.3 mW at 1030 nm.In addition,using the electro-optic effect of lithium niobate,we achieve a laser tuning efficiency of 4 pm/V.This work opens the path to on-chip high-power and mode-locked ultrafast laser output.
基金National Natural Science Foundation of China(62205317).
文摘Stimulated Brillouin scattering(SBS)-induced mode distortion(MD)in high power narrow linewidth fiber amplifiers has been implemented,and the origin has been investigated from the aspect of the evolution of the optical spectrum,spatial beam profiles,and temporal-frequency domain characteristics.
基金supported by Huo Ying Dong Education Foundation of China(No.151062)the Foundation for the author of National Excellent Doctoral Dissertation of China(No.201329)
文摘In this manuscript, we demonstrate high-power, narrow-linewidth linearly polarized fiber laser with excellent beam quality through compact one-stage amplification scheme. By employing a single-mode–multimode–single-mode structure seed laser, a linearly polarized Yb-doped fiber laser with narrow linewidth and high output power is achieved.This laser, when used as a master oscillator, can be capable of suppressing the ASE in the process of power amplification.Thus, only one-stage amplification structure is used to scale up the laser power, and linearly polarized output with a polarization extinction ration of 14 d B, a narrow linewidth of 0.3 nm and an output power of 1018 W are achieved.Moreover, due to the good beam quality of seed laser and the well-designed amplifier stage, the beam quality of the output laser is near-diffraction-limited with M_x^2 ~1.18 and M_y^2 ~ 1.24 at the maximum power, and without mode instability occurring.
基金National Natural Science Foundation of China(NSFC)(62005313,62035015)Innovative Research Team in Natural Science Foundation of Hunan Province(2019JJ10005).
文摘In this work,an all-fiberized and narrow-linewidth fiber amplifier with record output power and near-diffraction-limited beam quality is presented.Up to 6.12 kW fiber laser with the conversion efficiency of approximately 78.8%is achieved through the fiber amplifier based on a conventional step-index active fiber.At the maximum output power,the 3 dB spectral linewidth is approximately 0.86 nm and the beam quality factor is M_(x)^(2)=1.43,M_(y)^(2)=1.36.We have also measured and compared the output properties of the fiber amplifier employing different pumping schemes.Notably,the practical power limit of the fiber amplifier could be estimated through the maximum output powers of the fiber amplifier employing unidirectional pumping schemes.Overall,this work could provide a good reference for the optimal design and potential exploration of high-power narrow-linewidth fiber laser systems.
基金This work was supported by the Director Foundation of State Key Laboratory of Pulsed Power Laser Technology(No.SKL2019ZR06)Open Research Foundation of State Key Laboratory of Pulsed Power Laser Technology(No.SKL2019KF05).
文摘The linewidth of the BaGa_(4)Se_(7)(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 350μm 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.
基金This work was supported by the National Natural Science Foundation of China(NSFC)(No.61991433)Pilot Project of CAS(No.XDB43030302)+2 种基金Equipment Pre-research(No.2006ZYGG0304)Key Research and Development Project of Guangdong Province(No.2020B090922003)R&D Program of Jilin Province(No.20190302042GX).
文摘In this research,the highly efficient external cavity feedback technology based on volume Bragg grating(VBG)is studied.By using the structure of a fast axis collimating lens,the beam transformation system,a slow axis collimating lens,and VBG,the divergence angle of the fast and slow axes of the diode laser incident on the VBG is reduced effectively,and the feedback efficiency of the external cavity is improved.Combined with beam combining technology,fiber coupling technology,and precision temperature control technology,a high-power and narrow-linewidth diode laser pump source of kilowatt class is realized for alkali metal vapor laser pumping.The core diameter of the optical fiber is 1000μm,the numerical aperture is 0.22,the output power from the fiber is 1013 W,the fiber coupling efficiency exceeds 89%,and the external cavity efficiency exceeds 91%.The central wavelength is 852.052 nm(in air),which is tunable from 851.956 nm to 852.152 nm,and the spectral linewidth is 0.167 nm.Research results can be used for cesium alkali metal vapor laser pumping.
