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
We propose a theoretical model to describe external-cavity distributed feedback semiconductor lasers and investigate the impact of the number of external feedback points on linewidth and side-mode suppression ratio th...We propose a theoretical model to describe external-cavity distributed feedback semiconductor lasers and investigate the impact of the number of external feedback points on linewidth and side-mode suppression ratio through numerical simulation. The simulation results demonstrate that the linewidth of external-cavity semiconductor lasers can be reduced by increasing the external cavity length and feedback ratio, and adding more external feedback points can further narrow the linewidth and enhance the side mode suppression ratio. This research provides insight into the external cavity distributed feedback mechanism and can guide the design of high-performance external cavity semiconductor lasers. .展开更多
We report a type-I Ga Sb-based laterally coupled distributed-feedback(LC-DFB) laser with shallow-etched gratings operating a continuous wave at room temperature without re-growth process. Second-order Bragg gratings...We report a type-I Ga Sb-based laterally coupled distributed-feedback(LC-DFB) laser with shallow-etched gratings operating a continuous wave at room temperature without re-growth process. Second-order Bragg gratings are fabricated alongside the ridge waveguide by interference lithography. Index-coupled LC-DFB laser with a cavity of 1500 μm achieves single longitudinal mode continuous-wave operation at 20℃ with side mode suppression ratio(SMSR) as high as 24 dB.The maximum single mode continuous-wave output power is about 10 mW at room temperature(uncoated facet). A low threshold current density of 230 A/cm^2 is achieved with differential quantum efficiency estimated to be 93 mW/A. The laser shows a good wavelength stability against drive current and working temperature.展开更多
Modulation bandwidth enhancement in a directly modulated two-section distributed feedback(TS-DFB)laser based on a detuned loading effect is investigated and experimentally demonstrated.The results show that the 3-dB b...Modulation bandwidth enhancement in a directly modulated two-section distributed feedback(TS-DFB)laser based on a detuned loading effect is investigated and experimentally demonstrated.The results show that the 3-dB bandwidth of the TS-DFB laser is increased to 17.6 GHz and that chirp parameter can be reduced to 2.24.Compared to the absence of a detuned loading effect,there is a 4.6 GHz increase and a 2.45 reduction,respectively.After transmitting a 10 Gb/s non-return-to-zero(NRZ)signal through a 5-km fiber,the modulation eye diagram still achieves a large opening.Eight-channel laser arrays with precise wavelength spacing are fabricated.Each TS-DFB laser in the array has side mode suppression ratios(SMSR)>49.093 dB and the maximum wavelength residual<0.316 nm.展开更多
A 7.8-μm surface emitting second-order distributed feedback quantum cascade laser (DFB QCL) structure with metallized surface grating is studied. The modal property of this structure is described by utilizing coupl...A 7.8-μm surface emitting second-order distributed feedback quantum cascade laser (DFB QCL) structure with metallized surface grating is studied. The modal property of this structure is described by utilizing coupled-mode theory where the coupling coefficients are derived from exact Floquet-Bloch solutions of infinite periodic structure. Based on this theory, the influence of waveguide structure and grating topography as well as device length on the laser performance is numerically investigated. The optimized surface emitting second-order DFB QCL structure design exhibits a high surface outcoupling efficiency of 22% and a low threshold gain of 10 cm-1. Using a π phase-shift in the centre of the grating, a high-quality single-lobe far-field radiation pattern is obtained.展开更多
Monolithic integration of four 1.55-μm-range InGaAsP/InP distributed feedback (DFB) lasers using varied ridge width with a 4 x 1-multimode-interference (MMI) optical combiner and a semiconductor optical amplifier...Monolithic integration of four 1.55-μm-range InGaAsP/InP distributed feedback (DFB) lasers using varied ridge width with a 4 x 1-multimode-interference (MMI) optical combiner and a semiconductor optical amplifier (SOA) is demon- strated. The average output power and the threshold current are 1.8 mW and 35 mA, respectively, when the injection current of the SOA is 100 mA, with a side mode suppression ratio (SMSR) exceeding 40 dB. The four channels have a 1-nm average channel spacing and can operate separately or simultaneously.展开更多
Usually GaAs/AlGaAs is utilized as an active layer material in laser diodes operating in the spectral range of 800- 850 nm. In this work, in addition to a traditional unstrained GaAs/AlGaAs distributed feedback (DFB...Usually GaAs/AlGaAs is utilized as an active layer material in laser diodes operating in the spectral range of 800- 850 nm. In this work, in addition to a traditional unstrained GaAs/AlGaAs distributed feedback (DFB) laser diode, a compressively strained InGaAlAs/AlGaAs DFB laser diode is numerically investigated in characteristic. The simulation results show that the compressively strained DFB laser diode has a lower transparency carrier density, higher gain, lower Auger recombination rate, and higher stimulated recombination rate, which lead to better a device performance, than the traditional unstrained GaAs/AlGaAs DFB laser diode.展开更多
By employing a simple model of describing three-level lasers, we have theoretically investigated the effect of photon lifetime on the output dynamics of Er-doped distributed feedback fibre lasers. And based on the the...By employing a simple model of describing three-level lasers, we have theoretically investigated the effect of photon lifetime on the output dynamics of Er-doped distributed feedback fibre lasers. And based on the theoretical analysis we have proposed a promising method to suppress self-pulsing behaviour in the fibre lasers.展开更多
A 32 Gb/s monolithically integrated electroabsorption modulated laser is fabricated by selective area growth technology. The threshold current of the device is below 13mA. The output power exceeds 10mW at 0V bias when...A 32 Gb/s monolithically integrated electroabsorption modulated laser is fabricated by selective area growth technology. The threshold current of the device is below 13mA. The output power exceeds 10mW at 0V bias when the injection current of the distributed feedback laser is 100mA at 25℃. The side mode suppression ratio is over 50 dB. A 32Gb/s eye diagram is measured with a 3.SVpp nonreturn-to-zero pseudorandom modulation signal at -2.3 V bias. A clearly opening eyediagram with a dynamic extinction ratio of 8.01 dB is obtained.展开更多
The 795 nm distributed feedback lasers have great application in pumping the Rb D1 transition.In this paper,in order to realize specific 795 nm lasing,we designed tilted ridge distributed feedback lasers based on pure...The 795 nm distributed feedback lasers have great application in pumping the Rb D1 transition.In this paper,in order to realize specific 795 nm lasing,we designed tilted ridge distributed feedback lasers based on purely gain coupled effect induced by periodic current injection windows through changing the angle of the tilted ridge.The fabricated devices were cleaved into 2 mm-cavity-length,including 5 tilted angles.The peak output powers of all devices were above 30 mW.Single longitudinal mode lasing was realized in all tilted Fabry-Perot cavities using periodic current injection windows,with side mode suppression ratio over 30 dB.The total wavelength range covered 8.656 nm at 20℃.It was disclosed theoretically and experimentally that the output powers,threshold currents,and central wavelengths of the tilted ridge purely gain coupled DFB lasers were relevant to the tilted angles.The results will be instructive for future design of DFB laser arrays with different central wavelengths.展开更多
We report on the room-temperature cascade laser (QCL) at λ -4.7μm. cw operation of a surface grating Both grating design and material distributed feedback (DFB) quantum optimization are used to decrease the thre...We report on the room-temperature cascade laser (QCL) at λ -4.7μm. cw operation of a surface grating Both grating design and material distributed feedback (DFB) quantum optimization are used to decrease the threshold current density and to increase the output power. For a high-reflectivity-coated 13-μm-wide and 4- mm-long laser, high wall-plug efficiency of 6% is obtained at 20℃ from a single facet producing over I W of ew output power. The threshold current density of DFB QCL is as low as 1.13kA/cm^2 at 10℃ and 1.34kA/cm2 at 30℃ in cw mode. Stable single-mode emission with a side-mode suppression ratio of about 30 dB is observed in tile working temperature range of 20-50℃.展开更多
Integrated electro-absorption-modulated distributed feedback laser diodes(EMLs)are attracting much interest in optical communications for the advantages of a compact structure,low power consumption,and high-speed modu...Integrated electro-absorption-modulated distributed feedback laser diodes(EMLs)are attracting much interest in optical communications for the advantages of a compact structure,low power consumption,and high-speed modulation.In integrated EML,the microwave interaction between the distributed feedback laser diode(DFB-LD)and the electro-absorption modulator(EAM)has a nonnegligible influence on the modulation performance,especially at the high-frequency region.In this paper,integrated EML was investigated as a three-port network with two electrical inputs and a single optical output,where the scattering matrix of the integrated device was theoretically deduced and experimentally measured.Based on the theoretical model and the measured data,the microwave equivalent circuit model of the integrated device was established,from which the microwave interaction between DFB-LD and EAM was successfully extracted.The results reveal that the microwave interaction within integrated EML contains both the electrical isolation and optical coupling.The electrical isolation is bidirectional while the optical coupling is directional,which aggravates the microwave interaction in the direction from DFB-LD to EAM.展开更多
A new device of two parallel distributed feedback (DFB) lasers integrated monolithically with Y-branch waveguide coupler was fabricated by means of quantum well intermixing. Optical microwave signal was generated in...A new device of two parallel distributed feedback (DFB) lasers integrated monolithically with Y-branch waveguide coupler was fabricated by means of quantum well intermixing. Optical microwave signal was generated in the Y-branch waveguide coupler through frequency beating of the two laser modes coming from two DFB laser in parallel, which had a small difference in frequency. Continuous rapid tuning of optical microwave signal from 13 to 42 GHz were realized by adjusting independently the driving currents injected into the two DFB lasers.展开更多
The effects of time-delayed feedback control in a single-mode laser system is investigated.Using the smalltime delay approximation,the analytic expression of the stationary probability distribution function of the las...The effects of time-delayed feedback control in a single-mode laser system is investigated.Using the smalltime delay approximation,the analytic expression of the stationary probability distribution function of the laser field isobtained.The mean,normalized variance and skewness of the steady-state laser intensity are calculated.It is found thatthe time-delayed feedback control can suppress the intensity fluctuation of the laser system.The numerical simulationsare in good agreement with the approximate analytic results.展开更多
This paper presents an optimized asymmetric three corrugation-pitch-modulated DFB laser (3CPM-DFB) with extremely high mode selectivity(△αL= 0.97) and low flatness(F = 0.009), which are two key parameters to indicat...This paper presents an optimized asymmetric three corrugation-pitch-modulated DFB laser (3CPM-DFB) with extremely high mode selectivity(△αL= 0.97) and low flatness(F = 0.009), which are two key parameters to indicate the laser’s single longitudinal mode(SLM) performance. In threshold analysis, the optimization process based on transfer matrix method is demonstrated to maximize △αL?and minimize F simultaneously. In the above-threshold regime, the evolutions of △αL?and?longitudinal distribution of photon density with injection current are evaluated. More importantly, nanoimprint lithography which was proved an efficient way to fabricate DFB gratings can provide completely same simple fabrication procedure for both 3CPM grating and conventional uniform grating. So the big practical value of 3CPM-DFB can be expected because of its advanced performance and easy manufacturability.展开更多
A distributed feedback fiber laser based Bragg grating vibration sensor system is proposed.Demodulated by using an unbalanced M-Z interferometer,experiment demonstrates that the system runs at a sensing sensitivity of...A distributed feedback fiber laser based Bragg grating vibration sensor system is proposed.Demodulated by using an unbalanced M-Z interferometer,experiment demonstrates that the system runs at a sensing sensitivity of about 257.2 rad·s2/m and a resolution of 4.2×10-5 m/s2 for monitoring acceleration.Experimental results show that the phase-shift changes with the acceleration linearly.展开更多
The steady-state gain distribution in cladding pumped thulium-doped fiber laser(TDFL) is analytically and numerically solved based on the rate equations including loss coefficients and cross relaxation effect. With ...The steady-state gain distribution in cladding pumped thulium-doped fiber laser(TDFL) is analytically and numerically solved based on the rate equations including loss coefficients and cross relaxation effect. With the gain curve, a problem, which is named optical feedback inhibition(OFI) and always occurs in tandem TDFL-Ho:YAG laser system, is analyzed quantitatively. The actual characteristics of output spectra and power basically prove the conclusion of theoretical analysis. Then a simple mirror-deflected L-shaped cavity is employed to restrain the external feedback and simplify the structure of fiber-bulk Ho:YAG laser. Finally, 25 W of 2097-nm laser power and 51.2% of optical-to-optical conversion efficiency are obtained, and the beam quality factor is less than 1.43 obtained by knife-edge method.展开更多
This paper reports that the complex-coupled distributed feedback laser with the sampled grating has been designed and fabricated.The +1st order reflection of the sampled grating is utilized for laser single mode oper...This paper reports that the complex-coupled distributed feedback laser with the sampled grating has been designed and fabricated.The +1st order reflection of the sampled grating is utilized for laser single mode operation,which is 1.5387 μm in the experiment.The typical threshold current of the device is 30 mA,and the optical output power is about 10 mW at the injection current of 100 mA.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.
文摘We propose a theoretical model to describe external-cavity distributed feedback semiconductor lasers and investigate the impact of the number of external feedback points on linewidth and side-mode suppression ratio through numerical simulation. The simulation results demonstrate that the linewidth of external-cavity semiconductor lasers can be reduced by increasing the external cavity length and feedback ratio, and adding more external feedback points can further narrow the linewidth and enhance the side mode suppression ratio. This research provides insight into the external cavity distributed feedback mechanism and can guide the design of high-performance external cavity semiconductor lasers. .
基金Project supported by the National Key Basic Research Program of China(Grant Nos.2014CB643903 and 2013CB932904)the National Special Funds for the Development of Major Research Equipment and Instruments,China(Grant No.2012YQ140005)+1 种基金the National Natural Science Foundation of China(Grant Nos.61435012,61274013,61306088,and 61290303)the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB01010200)
文摘We report a type-I Ga Sb-based laterally coupled distributed-feedback(LC-DFB) laser with shallow-etched gratings operating a continuous wave at room temperature without re-growth process. Second-order Bragg gratings are fabricated alongside the ridge waveguide by interference lithography. Index-coupled LC-DFB laser with a cavity of 1500 μm achieves single longitudinal mode continuous-wave operation at 20℃ with side mode suppression ratio(SMSR) as high as 24 dB.The maximum single mode continuous-wave output power is about 10 mW at room temperature(uncoated facet). A low threshold current density of 230 A/cm^2 is achieved with differential quantum efficiency estimated to be 93 mW/A. The laser shows a good wavelength stability against drive current and working temperature.
文摘Modulation bandwidth enhancement in a directly modulated two-section distributed feedback(TS-DFB)laser based on a detuned loading effect is investigated and experimentally demonstrated.The results show that the 3-dB bandwidth of the TS-DFB laser is increased to 17.6 GHz and that chirp parameter can be reduced to 2.24.Compared to the absence of a detuned loading effect,there is a 4.6 GHz increase and a 2.45 reduction,respectively.After transmitting a 10 Gb/s non-return-to-zero(NRZ)signal through a 5-km fiber,the modulation eye diagram still achieves a large opening.Eight-channel laser arrays with precise wavelength spacing are fabricated.Each TS-DFB laser in the array has side mode suppression ratios(SMSR)>49.093 dB and the maximum wavelength residual<0.316 nm.
基金Project supported by the National Science Fund for Distinguished Young Scholars of China (Grant No. 60525406)the National Natural Science Foundation of China (Grant Nos. 60736031,60806018,and 60906026)+1 种基金the National Basic Research Program of China (Grant No. 2006CB604903)the National High Technology Research and Development Program of China (Grant Nos. 2007AA03Z446 and 2009AA03Z403)
文摘A 7.8-μm surface emitting second-order distributed feedback quantum cascade laser (DFB QCL) structure with metallized surface grating is studied. The modal property of this structure is described by utilizing coupled-mode theory where the coupling coefficients are derived from exact Floquet-Bloch solutions of infinite periodic structure. Based on this theory, the influence of waveguide structure and grating topography as well as device length on the laser performance is numerically investigated. The optimized surface emitting second-order DFB QCL structure design exhibits a high surface outcoupling efficiency of 22% and a low threshold gain of 10 cm-1. Using a π phase-shift in the centre of the grating, a high-quality single-lobe far-field radiation pattern is obtained.
基金Project supported by the National High Technology Research and Pevelopment Program of China (Grant Nos. 2011AA010303 and 2012AA012203)the National Basic Research Program of China (Grant No. 2011CB301702)the National Natural Science Foundation of China (Grant Nos. 61021003 and 61090392)
文摘Monolithic integration of four 1.55-μm-range InGaAsP/InP distributed feedback (DFB) lasers using varied ridge width with a 4 x 1-multimode-interference (MMI) optical combiner and a semiconductor optical amplifier (SOA) is demon- strated. The average output power and the threshold current are 1.8 mW and 35 mA, respectively, when the injection current of the SOA is 100 mA, with a side mode suppression ratio (SMSR) exceeding 40 dB. The four channels have a 1-nm average channel spacing and can operate separately or simultaneously.
基金Project supported by the National Natural Science Foundation of China (Grant No 10374085). Acknowledgment The authors would like to thank the members of the nano-opotoelectronics laboratory for helpful discussion.
文摘Usually GaAs/AlGaAs is utilized as an active layer material in laser diodes operating in the spectral range of 800- 850 nm. In this work, in addition to a traditional unstrained GaAs/AlGaAs distributed feedback (DFB) laser diode, a compressively strained InGaAlAs/AlGaAs DFB laser diode is numerically investigated in characteristic. The simulation results show that the compressively strained DFB laser diode has a lower transparency carrier density, higher gain, lower Auger recombination rate, and higher stimulated recombination rate, which lead to better a device performance, than the traditional unstrained GaAs/AlGaAs DFB laser diode.
基金Project supported by the National High Technology Research and Development Program of China (Grant No 842010)the Fund of Shanghai Optics Science and Technology, China (Grant No 05DZ2007)
文摘By employing a simple model of describing three-level lasers, we have theoretically investigated the effect of photon lifetime on the output dynamics of Er-doped distributed feedback fibre lasers. And based on the theoretical analysis we have proposed a promising method to suppress self-pulsing behaviour in the fibre lasers.
基金Supported by the National High-Technology Research and Development Program of China under Grant Nos 2011AA010303and 2012AA012203the National Basic Research Program of China under Grant No 2011CB301702the National Natural Science Foundation of China under Grant Nos 61321063 and 6132010601
文摘A 32 Gb/s monolithically integrated electroabsorption modulated laser is fabricated by selective area growth technology. The threshold current of the device is below 13mA. The output power exceeds 10mW at 0V bias when the injection current of the distributed feedback laser is 100mA at 25℃. The side mode suppression ratio is over 50 dB. A 32Gb/s eye diagram is measured with a 3.SVpp nonreturn-to-zero pseudorandom modulation signal at -2.3 V bias. A clearly opening eyediagram with a dynamic extinction ratio of 8.01 dB is obtained.
基金the National Science and Technology Major Project of China(Grant Nos.2017YFB0503100,2018YFB0504600,2018YFB2200300,and 2020YFB2205902)Frontier Science Key Program of the President of the Chinese Academy of Sciences(Grant No.QYZDY-SSW-JSC006)+3 种基金the National Natural Science Foundation of China(Grant Nos.62090051,62090052,62090054,11874353,61935009,61934003,61904179,61727822,61805236,and 62004194)Science and Technology Development Project of Jilin Province,China(Grant Nos.20200401069GX,20200401062GX,20200501007GX,20200501008GX,and 20200501009GX)Special Scientific Research Project of Academician Innovation Platform in Hainan Province,China(Grant No.YSPTZX202034)Dawn Talent Training Program of CIOMP,and Independent Innovation Project of State Key Laboratory of Luminescence and Applications(Grant No.SKL1-Z-2020-02).
文摘The 795 nm distributed feedback lasers have great application in pumping the Rb D1 transition.In this paper,in order to realize specific 795 nm lasing,we designed tilted ridge distributed feedback lasers based on purely gain coupled effect induced by periodic current injection windows through changing the angle of the tilted ridge.The fabricated devices were cleaved into 2 mm-cavity-length,including 5 tilted angles.The peak output powers of all devices were above 30 mW.Single longitudinal mode lasing was realized in all tilted Fabry-Perot cavities using periodic current injection windows,with side mode suppression ratio over 30 dB.The total wavelength range covered 8.656 nm at 20℃.It was disclosed theoretically and experimentally that the output powers,threshold currents,and central wavelengths of the tilted ridge purely gain coupled DFB lasers were relevant to the tilted angles.The results will be instructive for future design of DFB laser arrays with different central wavelengths.
基金Supported by the National Basic Research Program of China under Grant Nos 2013CB632801 and 2013CB632803the National Natural Science Foundation of China under Grant Nos 61435014,61306058 and 61274094the Beijing Natural Science Foundation under Grant No 4144086
文摘We report on the room-temperature cascade laser (QCL) at λ -4.7μm. cw operation of a surface grating Both grating design and material distributed feedback (DFB) quantum optimization are used to decrease the threshold current density and to increase the output power. For a high-reflectivity-coated 13-μm-wide and 4- mm-long laser, high wall-plug efficiency of 6% is obtained at 20℃ from a single facet producing over I W of ew output power. The threshold current density of DFB QCL is as low as 1.13kA/cm^2 at 10℃ and 1.34kA/cm2 at 30℃ in cw mode. Stable single-mode emission with a side-mode suppression ratio of about 30 dB is observed in tile working temperature range of 20-50℃.
基金This work was supported by the National Key Research and Development Program of China under Grant No.2018YFE0201900the National Natural Science Foundation of China under Grants No.61927821 and No.61875240the Joint Research Fund of Ministry of Education of China under Grant No.6141A02022436.
文摘Integrated electro-absorption-modulated distributed feedback laser diodes(EMLs)are attracting much interest in optical communications for the advantages of a compact structure,low power consumption,and high-speed modulation.In integrated EML,the microwave interaction between the distributed feedback laser diode(DFB-LD)and the electro-absorption modulator(EAM)has a nonnegligible influence on the modulation performance,especially at the high-frequency region.In this paper,integrated EML was investigated as a three-port network with two electrical inputs and a single optical output,where the scattering matrix of the integrated device was theoretically deduced and experimentally measured.Based on the theoretical model and the measured data,the microwave equivalent circuit model of the integrated device was established,from which the microwave interaction between DFB-LD and EAM was successfully extracted.The results reveal that the microwave interaction within integrated EML contains both the electrical isolation and optical coupling.The electrical isolation is bidirectional while the optical coupling is directional,which aggravates the microwave interaction in the direction from DFB-LD to EAM.
基金Project supported by the National Natural Science Foundation of China (Grant No 90401025). Acknowledgments The authors are grateful to the Multiple-function 0ptoelectronic Integration group, Institute of Semiconductors, CAS for sponsoring this project. We extend our thanks to Professor Wang Zi-Yu of Peking University for microwave signal testing.
文摘A new device of two parallel distributed feedback (DFB) lasers integrated monolithically with Y-branch waveguide coupler was fabricated by means of quantum well intermixing. Optical microwave signal was generated in the Y-branch waveguide coupler through frequency beating of the two laser modes coming from two DFB laser in parallel, which had a small difference in frequency. Continuous rapid tuning of optical microwave signal from 13 to 42 GHz were realized by adjusting independently the driving currents injected into the two DFB lasers.
文摘The effects of time-delayed feedback control in a single-mode laser system is investigated.Using the smalltime delay approximation,the analytic expression of the stationary probability distribution function of the laser field isobtained.The mean,normalized variance and skewness of the steady-state laser intensity are calculated.It is found thatthe time-delayed feedback control can suppress the intensity fluctuation of the laser system.The numerical simulationsare in good agreement with the approximate analytic results.
文摘This paper presents an optimized asymmetric three corrugation-pitch-modulated DFB laser (3CPM-DFB) with extremely high mode selectivity(△αL= 0.97) and low flatness(F = 0.009), which are two key parameters to indicate the laser’s single longitudinal mode(SLM) performance. In threshold analysis, the optimization process based on transfer matrix method is demonstrated to maximize △αL?and minimize F simultaneously. In the above-threshold regime, the evolutions of △αL?and?longitudinal distribution of photon density with injection current are evaluated. More importantly, nanoimprint lithography which was proved an efficient way to fabricate DFB gratings can provide completely same simple fabrication procedure for both 3CPM grating and conventional uniform grating. So the big practical value of 3CPM-DFB can be expected because of its advanced performance and easy manufacturability.
基金supported by the Science Fund for Young Scholars of Heilongjiang University,China(No.QL200901)
文摘A distributed feedback fiber laser based Bragg grating vibration sensor system is proposed.Demodulated by using an unbalanced M-Z interferometer,experiment demonstrates that the system runs at a sensing sensitivity of about 257.2 rad·s2/m and a resolution of 4.2×10-5 m/s2 for monitoring acceleration.Experimental results show that the phase-shift changes with the acceleration linearly.
基金Project supported by the National Natural Science Foundation of China(Grant No.61275146)the Research Fund for the Doctoral Program of Higher Education of China(Grant No.20120002110066)the Special Program of the Co-construction with Beijing Municipal Government of China(Grant No.20121000302)
文摘The steady-state gain distribution in cladding pumped thulium-doped fiber laser(TDFL) is analytically and numerically solved based on the rate equations including loss coefficients and cross relaxation effect. With the gain curve, a problem, which is named optical feedback inhibition(OFI) and always occurs in tandem TDFL-Ho:YAG laser system, is analyzed quantitatively. The actual characteristics of output spectra and power basically prove the conclusion of theoretical analysis. Then a simple mirror-deflected L-shaped cavity is employed to restrain the external feedback and simplify the structure of fiber-bulk Ho:YAG laser. Finally, 25 W of 2097-nm laser power and 51.2% of optical-to-optical conversion efficiency are obtained, and the beam quality factor is less than 1.43 obtained by knife-edge method.
基金Project supported by the National High-Tech Research and Development Programm of China (Grant Nos 2006AA01Z256,2007AA03Z419 and 2007AA03Z417)the National Key Basic Research Programm of China (Grant Nos 2006CB604901 and 2006CB604902)the National Natural Science Foundation of China (Grant Nos 90401025,60736036,60706009 and 60777021)
文摘This paper reports that the complex-coupled distributed feedback laser with the sampled grating has been designed and fabricated.The +1st order reflection of the sampled grating is utilized for laser single mode operation,which is 1.5387 μm in the experiment.The typical threshold current of the device is 30 mA,and the optical output power is about 10 mW at the injection current of 100 mA.