Wavelength-tunable organic semiconductor lasers based on mechanically stretchable polydimethylsiloxane (PDMS) gratings were developed. The intrinsic stretchability of PDMS was explored to modulate the period of the di...Wavelength-tunable organic semiconductor lasers based on mechanically stretchable polydimethylsiloxane (PDMS) gratings were developed. The intrinsic stretchability of PDMS was explored to modulate the period of the distributed feedback gratings for fine tuning the lasing wavelength. Notably, elastic lasers based on three typical light-emitting molecules show com-parable lasing threshold values analogous to rigid devices and a continuous wavelength tunability of about 10 nm by mechanic-al stretching. In addition, the stretchability provides a simple solution for dynamically tuning the lasing wavelength in a spec-tral range that is challenging to achieve for inorganic counterparts. Our work has provided a simple and efficient method of fab-ricating tunable organic lasers that depend on stretchable distributed feedback gratings, demonstrating a significant step in the advancement of flexible organic optoelectronic devices.展开更多
Sensitive detection of hydrogen sulfide(H2S) has been performed by means of wavelength modulation spectroscopy(WMS) near 1.578 μm. With the scan amplitude and the stability of the background baseline taken into a...Sensitive detection of hydrogen sulfide(H2S) has been performed by means of wavelength modulation spectroscopy(WMS) near 1.578 μm. With the scan amplitude and the stability of the background baseline taken into account, the response time is 4 s for a 0.8 L multi-pass cell with a 56.7 m effective optical path length. Moreover, the linearity has been tested in the 0–50 ppmv range. The detection limit achievable by the Allan variance is 224 ppb within 24 s under room temperature and ambient pressure conditions. This tunable diode laser absorption spectroscopy(TDLAS) system for H2 S detection has the feasibility of real-time online monitoring in many applications.展开更多
A wide wavelength tuning range and single-mode hybrid cavity laser consists of a square Whispering-Gallery(WG)microcavity and a Fabry–Pérot(FP)was introduced and demonstrated.A wavelength tuning range over 12.5 ...A wide wavelength tuning range and single-mode hybrid cavity laser consists of a square Whispering-Gallery(WG)microcavity and a Fabry–Pérot(FP)was introduced and demonstrated.A wavelength tuning range over 12.5 nm from 1760.87 to 1773.39 nm which was single-mode emitting was obtained with the side-mode suppression ratio over 30 dB.The hybrid cavity laser does not need grating etching and special epitaxial structure,which reduces the fabrication difficulty and cost,and shows the potential for gas sensing with absorption lines in this range.展开更多
We demonstrate a passively Q-switched tunable erbium-doped fiber laser (EDFL) based on graphene as a saturable absorber (SA). A three-port optical circulator (OC) and a strain-induced tunable fiber Bragg grating...We demonstrate a passively Q-switched tunable erbium-doped fiber laser (EDFL) based on graphene as a saturable absorber (SA). A three-port optical circulator (OC) and a strain-induced tunable fiber Bragg grating (TFBG) are used as the two end mirrors in an all-fiber linear cavity. The Q-switched EDFL has a low pump threshold of 23.8 mW. The pulse repetition rate of the fiber laser can be widely changed from 9.3 kHz to 69.7 kHz by increasing the pump power from 23.8 mW to 219.9 mW. The minimum pulse duration is 1.7 p.s and the highest pulse energy is 25.4 nJ. The emission wavelength of the laser can be tuned from 1560.43 nm to 1566.27 nm by changing the central wavelength of the straininduced TFBG.展开更多
Single crystal of Yb x Y 1- x Al 3(BO 3) 4 (Yb∶YAB) was grown by using flux method based on the potassium trimolybdate. 160 mW efficient continuous wave green output was obtained from a fibre coupled ...Single crystal of Yb x Y 1- x Al 3(BO 3) 4 (Yb∶YAB) was grown by using flux method based on the potassium trimolybdate. 160 mW efficient continuous wave green output was obtained from a fibre coupled 976 nm laser diode. The conversion efficiency is larger than 11 3%, and the electrical input green conversion efficiency is 3 9%. Tunable green output from 513 0 to 545 8 nm is also demonstrated with a quartz birefringent filter. By enhancing the incident pump power, 1 1 W cw green output can be reached.展开更多
Development of a high power fiber laser at special waveband,which is difficult to achieve by conventional rare-earth-doped fibers,is a significant challenge.One of the most common methods for achieving lasing at speci...Development of a high power fiber laser at special waveband,which is difficult to achieve by conventional rare-earth-doped fibers,is a significant challenge.One of the most common methods for achieving lasing at special wavelength is Raman conversion.Phosphorus-doped fiber(PDF),due to the phosphorus-related large frequency shift Raman peak at 40 THz,is a great choice for large frequency shift Raman conversion.Here,by adopting 150 m large mode area triple-clad PDF as Raman gain medium,and a novel wavelength-selective feedback mechanism to suppress the silica-related Raman emission,we build a high power cladding-pumped Raman fiber laser at 1.2μm waveband.A Raman signal with power up to 735.8 W at 1252.7 nm is obtained.To the best of our knowledge,this is the highest output power ever reported for fiber lasers at 1.2μm waveband.Moreover,by tuning the wavelength of the pump source,a tunable Raman output of more than 450 W over a wavelength range of 1240.6–1252.7 nm is demonstrated.This work proves PDF’s advantage in high power large frequency shift Raman conversion with a cladding pump scheme,thus providing a good solution for a high power laser source at special waveband.展开更多
In this Letter, a 16 channel 200 GHz wavelength tunable arrayed waveguide grating(AWG) is designed and fabricated based on the silicon on insulator platform. Considering that the performance of the AWG, such as cent...In this Letter, a 16 channel 200 GHz wavelength tunable arrayed waveguide grating(AWG) is designed and fabricated based on the silicon on insulator platform. Considering that the performance of the AWG, such as central wavelength and crosstalk, is sensitive to the dimension variation of waveguides, the error analysis of the AWG with width fluctuations is worked out using the transfer function method. A heater is designed to realize the wavelength tunability of the AWG based on the thermo-optic effect of silicon. The measured results show that the insertion loss of the AWG is about 6 d B, and the crosstalk is 7.5 d B. The wavelength tunability of 1.1 nm is achieved at 276 m W power consumption, and more wavelength shifts will gain at larger power consumption.展开更多
We report on broadly wavelength-tunable passive mode-locking with high power operating at the 2 μm water absorption band in a Tm:CYA crystal laser. With a simple quartz plate, stable mode-locking wavelengths can be t...We report on broadly wavelength-tunable passive mode-locking with high power operating at the 2 μm water absorption band in a Tm:CYA crystal laser. With a simple quartz plate, stable mode-locking wavelengths can be tuned from 1874 to 1973 nm, with a tunable wavelength range up to ~100 nm and maximum output power up to 1.35 W. The bandwidth is narrow as ~6 GHz, corresponding to a high coherence. To our knowledge, this is the first demonstration of wavelength-tunable mode-locking with watt-level in the 2 μm water absorption band.The high temporal coherent laser can be further applied in spectroscopy, the efficient excitation of molecules, sensing, and quantum optics.展开更多
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 wa...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.展开更多
We report a demonstration of a fast wavelength tunable source (TWS) based on the laser diode array coupled to the arrayed waveguide grating (AWG) multiplexer. The switching and optical characteristics of TWS make it a...We report a demonstration of a fast wavelength tunable source (TWS) based on the laser diode array coupled to the arrayed waveguide grating (AWG) multiplexer. The switching and optical characteristics of TWS make it a candidate for implementing the wavelength-division space switch fabric for an optical packet/burst switching.展开更多
We report a wavelength and power monitoring system based on a scanning MEMS filter as wavelength discriminator and a near threshold-biased Fabry-Perot diode laser as wavelength reference. This system is capable of mon...We report a wavelength and power monitoring system based on a scanning MEMS filter as wavelength discriminator and a near threshold-biased Fabry-Perot diode laser as wavelength reference. This system is capable of monitoring 250 channels of DWDM signal at 25 GHz ITU Grid with an error of less than ±8 pm.展开更多
In this paper,we report on a wide wavelength tuning optical vortex carrying orbital angular momentum(OAM)of±?,from a thulium-doped yttrium aluminum perovskite(YAP)laser employing a birefringent filter.The OAM is ...In this paper,we report on a wide wavelength tuning optical vortex carrying orbital angular momentum(OAM)of±?,from a thulium-doped yttrium aluminum perovskite(YAP)laser employing a birefringent filter.The OAM is experimentally found to be well maintained during the whole wavelength tuning process.The Laguerre-Gaussian(LG_(0,+1))mode with a tuning range of 58 nm from 1934.8 to 1993.0 nm and LG0,-1mode with a range of 76 nm from 1920.4 to 1996.6 nm,are,respectively,obtained.This is,to the best of our knowledge,the first experimental implementation of wavelength tuning for a scalar vortex laser in the 2μm spectral range,as well as the broadest tuning range ever reported from the vortex laser cavity.Such a vortex laser with robust structure and straightforward wavelength tuning capability will be an ideal light source for potential applications in the field of optical communication with one additional degree of freedom.展开更多
Light beams carrying orbital angular momentum(OAM)have inspired various advanced applications,and such abundant practical applications in turn demand complex generation and manipulation of optical vortices.Here,we pro...Light beams carrying orbital angular momentum(OAM)have inspired various advanced applications,and such abundant practical applications in turn demand complex generation and manipulation of optical vortices.Here,we propose a multifocal graphene vortex generator,which can produce broadband angular momentum cascade containing continuous integer non-diffracting vortex modes.Our device naturally embodies a continuous spiral slit vortex generator and a zone plate,which enables the generation of high-quality continuous vortex modes with deep depths of foci.Meanwhile,the generated vortex modes can be simultaneously tuned through incident wavelength and position of the focal plane.The elegant structure of the device largely improves the design efficiency and can be fabricated by laser nanofabrication in a single step.Moreover,the outstanding property of graphene may enable new possibilities in enormous practical applications,even in some harsh environments,such as aerospace.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
The coexistence of a noise-like pulse(NLP)and a dark pulse was experimentally demonstrated in a net-anomalous dispersion Er/Yb co-doped fiber(EYDF)laser,for the first time,to our knowledge.The cavity was mode-locked b...The coexistence of a noise-like pulse(NLP)and a dark pulse was experimentally demonstrated in a net-anomalous dispersion Er/Yb co-doped fiber(EYDF)laser,for the first time,to our knowledge.The cavity was mode-locked by nonlinear polarization rotation(NPR)technique.Meanwhile,a Sagnac loop with a section of polarization-maintaining fiber(PMF)was used as a comb filter to enable multiwavelength pulse operation.When the PMF length was 0.3 m,an asymmetric two-peak spectrum with central wavelengths of 1565.3 and 1594.2 nm was obtained by adjusting polarization controllers(PCs).It is a composite state of NLP and dark pulse due to the cross-phase modulation between the two different wavelength components along orthogonal polarization axes.The two pulses are synchronized with a repetition rate of 7.53 MHz.By adjusting the PC in the Sagnac loop,the spectral ranges of NLPs and dark pulses can be tuned from 1560 to 1577.8 nm and from 1581.8 to 1605.4 nm,respectively.In addition,the pulse characteristics were investigated by incorporating the PMF with different lengths,where the coexistence patterns can be generated when the PMF lengths were 0.2 and 0.3 m.A longer PMF can lead to a narrowband comb filtering,which causes a larger loss and is not favorable for stable operation of the coexistence regime.This fiber laser demonstrates an interesting operation regime and has significant potential for numerous practical applications.展开更多
To the best of our knowledge,this is the first time that a mid-infrared Er^(3+):CaF_(2)-SrF_(2) laser has achieved continuous-wave mode-locked operation by a semiconductor saturable absorber mirror.The laser emits a m...To the best of our knowledge,this is the first time that a mid-infrared Er^(3+):CaF_(2)-SrF_(2) laser has achieved continuous-wave mode-locked operation by a semiconductor saturable absorber mirror.The laser emits a maximum output power of 93 mW at 2.73μm with a repetition rate of approximately 69 MHz and demonstrates a high signal-to-noise ratio of around 71 dB.In addition,a MgF_(2) birefringent plate was utilized to enable wavelength tuning of the Er^(3+):CaF_(2)-SrF_(2) laser,resulting in operation at approximately 2.73μm,2.75μm,2.79μm,and 2.81μm.These results demonstrate that Er^(3+):CaF_(2)-SrF_(2) is a promising alternative for the generation of efficient diode-pumped mode-locked lasers around 2.8μm.展开更多
基金financial support from the National Natural Science Foundation of China (21835003, 91833304,21422402, 62274097, 21674050, 62004106)the National Key Basic Research Program of China (2014CB648300,2017YFB0404501)+11 种基金the Natural Science Foundation of Jiangsu Province (BE2019120, BK20160888)Program for Jiangsu Specially-Appointed Professor (RK030STP15001)the Six Talent Peaks Project of Jiangsu Province (TD-XCL-009)the333 Project of Jiangsu Province (BRA2017402)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (20KJB140005)China Postdoctoral Science Foundation (2020M671553)the NUPT"1311 Project"and Scientific Foundation (NY217169, NY215062, NY215107,NY217087)the Leading Talent of Technological Innovation of National Ten-Thousands Talents Program of Chinathe Excellent Scientific and Technological Innovative Teams of Jiangsu Higher Education Institutions (TJ217038)the Postgraduate Research&Practice Innovation Program of Jiangsu Province (SJCX21-0297)the Synergetic Innovation Center for Organic Electronics and Information Displaysthe Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘Wavelength-tunable organic semiconductor lasers based on mechanically stretchable polydimethylsiloxane (PDMS) gratings were developed. The intrinsic stretchability of PDMS was explored to modulate the period of the distributed feedback gratings for fine tuning the lasing wavelength. Notably, elastic lasers based on three typical light-emitting molecules show com-parable lasing threshold values analogous to rigid devices and a continuous wavelength tunability of about 10 nm by mechanic-al stretching. In addition, the stretchability provides a simple solution for dynamically tuning the lasing wavelength in a spec-tral range that is challenging to achieve for inorganic counterparts. Our work has provided a simple and efficient method of fab-ricating tunable organic lasers that depend on stretchable distributed feedback gratings, demonstrating a significant step in the advancement of flexible organic optoelectronic devices.
基金supported by the Special Fund for Basic Research on Scientific Instruments of the Chinese Academy of Sciences(Grant No.YZ201315)the National Natural Science Foundation of China(Grant Nos.11204320,41405034,and 11204319)
文摘Sensitive detection of hydrogen sulfide(H2S) has been performed by means of wavelength modulation spectroscopy(WMS) near 1.578 μm. With the scan amplitude and the stability of the background baseline taken into account, the response time is 4 s for a 0.8 L multi-pass cell with a 56.7 m effective optical path length. Moreover, the linearity has been tested in the 0–50 ppmv range. The detection limit achievable by the Allan variance is 224 ppb within 24 s under room temperature and ambient pressure conditions. This tunable diode laser absorption spectroscopy(TDLAS) system for H2 S detection has the feasibility of real-time online monitoring in many applications.
基金This work was supported by the National Key Research and Development Program of China(Grant No.2018YFA0209001)the Key Project of Frontier Science Research Project of CAS(Grant No.QYZDY-SSW-JSC021)the Strategic Priority Research Program of CAS(Grant No.XDB43020202).
文摘A wide wavelength tuning range and single-mode hybrid cavity laser consists of a square Whispering-Gallery(WG)microcavity and a Fabry–Pérot(FP)was introduced and demonstrated.A wavelength tuning range over 12.5 nm from 1760.87 to 1773.39 nm which was single-mode emitting was obtained with the side-mode suppression ratio over 30 dB.The hybrid cavity laser does not need grating etching and special epitaxial structure,which reduces the fabrication difficulty and cost,and shows the potential for gas sensing with absorption lines in this range.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.61077017 and 61378028)the Program for New Century Excellent Talents in University,China (Grant Nos.NCET-11-0069 and NCET-10-0291)the 111 Project (Grant No.B13042)
文摘We demonstrate a passively Q-switched tunable erbium-doped fiber laser (EDFL) based on graphene as a saturable absorber (SA). A three-port optical circulator (OC) and a strain-induced tunable fiber Bragg grating (TFBG) are used as the two end mirrors in an all-fiber linear cavity. The Q-switched EDFL has a low pump threshold of 23.8 mW. The pulse repetition rate of the fiber laser can be widely changed from 9.3 kHz to 69.7 kHz by increasing the pump power from 23.8 mW to 219.9 mW. The minimum pulse duration is 1.7 p.s and the highest pulse energy is 25.4 nJ. The emission wavelength of the laser can be tuned from 1560.43 nm to 1566.27 nm by changing the central wavelength of the straininduced TFBG.
文摘Single crystal of Yb x Y 1- x Al 3(BO 3) 4 (Yb∶YAB) was grown by using flux method based on the potassium trimolybdate. 160 mW efficient continuous wave green output was obtained from a fibre coupled 976 nm laser diode. The conversion efficiency is larger than 11 3%, and the electrical input green conversion efficiency is 3 9%. Tunable green output from 513 0 to 545 8 nm is also demonstrated with a quartz birefringent filter. By enhancing the incident pump power, 1 1 W cw green output can be reached.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.61635005,61905284,and 62305391)the National Postdoctoral Program for Innovative Talents(No.BX20190063).
文摘Development of a high power fiber laser at special waveband,which is difficult to achieve by conventional rare-earth-doped fibers,is a significant challenge.One of the most common methods for achieving lasing at special wavelength is Raman conversion.Phosphorus-doped fiber(PDF),due to the phosphorus-related large frequency shift Raman peak at 40 THz,is a great choice for large frequency shift Raman conversion.Here,by adopting 150 m large mode area triple-clad PDF as Raman gain medium,and a novel wavelength-selective feedback mechanism to suppress the silica-related Raman emission,we build a high power cladding-pumped Raman fiber laser at 1.2μm waveband.A Raman signal with power up to 735.8 W at 1252.7 nm is obtained.To the best of our knowledge,this is the highest output power ever reported for fiber lasers at 1.2μm waveband.Moreover,by tuning the wavelength of the pump source,a tunable Raman output of more than 450 W over a wavelength range of 1240.6–1252.7 nm is demonstrated.This work proves PDF’s advantage in high power large frequency shift Raman conversion with a cladding pump scheme,thus providing a good solution for a high power laser source at special waveband.
基金supported by the National Key R&D Program of China(No.2016YFB0402504)the National Nature Science Foundation of China(Nos.61435013and 61405188)
文摘In this Letter, a 16 channel 200 GHz wavelength tunable arrayed waveguide grating(AWG) is designed and fabricated based on the silicon on insulator platform. Considering that the performance of the AWG, such as central wavelength and crosstalk, is sensitive to the dimension variation of waveguides, the error analysis of the AWG with width fluctuations is worked out using the transfer function method. A heater is designed to realize the wavelength tunability of the AWG based on the thermo-optic effect of silicon. The measured results show that the insertion loss of the AWG is about 6 d B, and the crosstalk is 7.5 d B. The wavelength tunability of 1.1 nm is achieved at 276 m W power consumption, and more wavelength shifts will gain at larger power consumption.
基金Natural Science Foundation of Jiangsu Province(BK20160221)Natural Science Foundation of Xuzhou,China(KC16SG247)+1 种基金Doctoral Research Funding of Jiangsu Normal University(15XLR024)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘We report on broadly wavelength-tunable passive mode-locking with high power operating at the 2 μm water absorption band in a Tm:CYA crystal laser. With a simple quartz plate, stable mode-locking wavelengths can be tuned from 1874 to 1973 nm, with a tunable wavelength range up to ~100 nm and maximum output power up to 1.35 W. The bandwidth is narrow as ~6 GHz, corresponding to a high coherence. To our knowledge, this is the first demonstration of wavelength-tunable mode-locking with watt-level in the 2 μm water absorption band.The high temporal coherent laser can be further applied in spectroscopy, the efficient excitation of molecules, sensing, and quantum optics.
文摘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.
文摘We report a demonstration of a fast wavelength tunable source (TWS) based on the laser diode array coupled to the arrayed waveguide grating (AWG) multiplexer. The switching and optical characteristics of TWS make it a candidate for implementing the wavelength-division space switch fabric for an optical packet/burst switching.
文摘We report a wavelength and power monitoring system based on a scanning MEMS filter as wavelength discriminator and a near threshold-biased Fabry-Perot diode laser as wavelength reference. This system is capable of monitoring 250 channels of DWDM signal at 25 GHz ITU Grid with an error of less than ±8 pm.
基金financially supported by the National Natural Science Foundation of China(Nos.52032009 and 62075090)Natural Science Foundation of Jiangsu Province(Nos.SBK2019030177 and SBX2021020083)Postgraduates Innovation Program of Jiangsu Province(No.KYCX21_2619)。
文摘In this paper,we report on a wide wavelength tuning optical vortex carrying orbital angular momentum(OAM)of±?,from a thulium-doped yttrium aluminum perovskite(YAP)laser employing a birefringent filter.The OAM is experimentally found to be well maintained during the whole wavelength tuning process.The Laguerre-Gaussian(LG_(0,+1))mode with a tuning range of 58 nm from 1934.8 to 1993.0 nm and LG0,-1mode with a range of 76 nm from 1920.4 to 1996.6 nm,are,respectively,obtained.This is,to the best of our knowledge,the first experimental implementation of wavelength tuning for a scalar vortex laser in the 2μm spectral range,as well as the broadest tuning range ever reported from the vortex laser cavity.Such a vortex laser with robust structure and straightforward wavelength tuning capability will be an ideal light source for potential applications in the field of optical communication with one additional degree of freedom.
基金the support from Advanced Research and Technology Innovation Centre(ARTIC)in National University of Singapore(R-261-518-004-720|A-0005947-1600)the Australia Research Council through the Discovery Project Scheme(DP190103186,DP220100603,and FT210100806)the Industrial Transformation Training Centre Scheme(IC180100005).
文摘Light beams carrying orbital angular momentum(OAM)have inspired various advanced applications,and such abundant practical applications in turn demand complex generation and manipulation of optical vortices.Here,we propose a multifocal graphene vortex generator,which can produce broadband angular momentum cascade containing continuous integer non-diffracting vortex modes.Our device naturally embodies a continuous spiral slit vortex generator and a zone plate,which enables the generation of high-quality continuous vortex modes with deep depths of foci.Meanwhile,the generated vortex modes can be simultaneously tuned through incident wavelength and position of the focal plane.The elegant structure of the device largely improves the design efficiency and can be fabricated by laser nanofabrication in a single step.Moreover,the outstanding property of graphene may enable new possibilities in enormous practical applications,even in some harsh environments,such as aerospace.
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.
基金This work was supported by the National Natural Science Foundation of China(NSFC)(No.61575018).
文摘The coexistence of a noise-like pulse(NLP)and a dark pulse was experimentally demonstrated in a net-anomalous dispersion Er/Yb co-doped fiber(EYDF)laser,for the first time,to our knowledge.The cavity was mode-locked by nonlinear polarization rotation(NPR)technique.Meanwhile,a Sagnac loop with a section of polarization-maintaining fiber(PMF)was used as a comb filter to enable multiwavelength pulse operation.When the PMF length was 0.3 m,an asymmetric two-peak spectrum with central wavelengths of 1565.3 and 1594.2 nm was obtained by adjusting polarization controllers(PCs).It is a composite state of NLP and dark pulse due to the cross-phase modulation between the two different wavelength components along orthogonal polarization axes.The two pulses are synchronized with a repetition rate of 7.53 MHz.By adjusting the PC in the Sagnac loop,the spectral ranges of NLPs and dark pulses can be tuned from 1560 to 1577.8 nm and from 1581.8 to 1605.4 nm,respectively.In addition,the pulse characteristics were investigated by incorporating the PMF with different lengths,where the coexistence patterns can be generated when the PMF lengths were 0.2 and 0.3 m.A longer PMF can lead to a narrowband comb filtering,which causes a larger loss and is not favorable for stable operation of the coexistence regime.This fiber laser demonstrates an interesting operation regime and has significant potential for numerous practical applications.
基金This work was supported by the National Natural Science Foundation of China(Nos.12374401,12104271,and 61925508)the Natural Science Foundation of Shandong Province(Nos.ZR2021LLZ008 and ZR2021QA030)the China Postdoctoral Science Foundation(No.2021M691981).
文摘To the best of our knowledge,this is the first time that a mid-infrared Er^(3+):CaF_(2)-SrF_(2) laser has achieved continuous-wave mode-locked operation by a semiconductor saturable absorber mirror.The laser emits a maximum output power of 93 mW at 2.73μm with a repetition rate of approximately 69 MHz and demonstrates a high signal-to-noise ratio of around 71 dB.In addition,a MgF_(2) birefringent plate was utilized to enable wavelength tuning of the Er^(3+):CaF_(2)-SrF_(2) laser,resulting in operation at approximately 2.73μm,2.75μm,2.79μm,and 2.81μm.These results demonstrate that Er^(3+):CaF_(2)-SrF_(2) is a promising alternative for the generation of efficient diode-pumped mode-locked lasers around 2.8μm.