This paper presents a wavelength-stepped swept laser based on a dispersion-tuned swept laser with the integration of a Mach-Zehnder interferometer,enabling a transition from continuous wavelength sweeping to wavelengt...This paper presents a wavelength-stepped swept laser based on a dispersion-tuned swept laser with the integration of a Mach-Zehnder interferometer,enabling a transition from continuous wavelength sweeping to wavelengthstepped sweeping.A comprehensive investigation of this laser is conducted,wherein different modulation schemes are employed to dynamically compare the switching mode,static-sweeping mode,and sweeping mode;the absence of mode hopping in the sweeping mode of the laser is verified.However,it is observed during experiments that the wavelength always remains stationary for a long time during the initiation of sweeping and change in sweeping direction,exhibiting latency compared to the modulation frequency variations.Through a simplistic modeling analysis of the composite cavity,it is revealed that the detuned state of the sub-cavity plays a critical role in the stable operation of the laser.Subsequently,simulation verification using the Ginzburg-Landau equation supports this observation.Additionally,compared to dispersion-tuned swept lasers,not only the linewidth significantly is narrowed in the proposed laser,but it also demonstrates enhanced stability during the sweeping process.This study provides,to our knowledge,a new laser source for ultra-fast optical imaging,ranging,and sensing applications,and presents novel methods and theoretical models for linewidth compression in swept lasers.展开更多
We demonstrate a fiber refractive index（RI） sensor based on an excessively tilted fiber grating（ExTFG）immobilized by large-size plasmonic gold nanoshells（GNSs）. The GNSs are covalently linked on ExTFG surface.Ex...We demonstrate a fiber refractive index（RI） sensor based on an excessively tilted fiber grating（ExTFG）immobilized by large-size plasmonic gold nanoshells（GNSs）. The GNSs are covalently linked on ExTFG surface.Experimental results demonstrate that both the intensity of the transverse magnetic（TM） and transverse electric（TE） modes of ExTFG are significantly modulated by the localized surface plasmon resonance（LSPR） of GNSs due to the wide-range absorption band. The wavelength RI sensitivities of the TM and TE modes in the low RI range of 1.333–1.379 are improved by ～25% and ～14% after GNSs immobilization, respectively, and the intensity RI sensitivities are ～599%/RIU and ～486%/RIU, respectively.展开更多
In this paper,we studied the dynamics of a dispersion-tuned swept-fiber laser both experimentally and theoretically.By adding a dispersion compensation fiber and an electro-optic modulator in the laser cavity,an activ...In this paper,we studied the dynamics of a dispersion-tuned swept-fiber laser both experimentally and theoretically.By adding a dispersion compensation fiber and an electro-optic modulator in the laser cavity,an actively mode-locked laser was obtained by using intensity modulation,and wavelength sweeping was realized by changing the modulation frequency.Using a high-speed real-time oscilloscope,the dynamic behaviors of the swept laser were investigated during wavelength switching,static-sweeping cycle,and continuous sweeping,respectively.It was found that the laser generates relaxation oscillation at the start of the sweeping mode.The relaxation oscillation process lasted for about 0.7 ms,and then the laser started to operate stably.Due to the nonlinear effect,new wavelengths were generated in the relaxation oscillation process,which is not beneficial for applications.Fortunately,relaxation oscillation disappears if the laser starts up and operates in the continuous sweeping mode,and the good sweeping symmetry between the positive sweep and negative sweep increases the application potential of the laser.In addition,the instantaneous linewidth is almost the same as that in the static state.These results describe the characteristics of the laser from a new perspective and reveal,to the best our knowledge,the intensity dynamics of such lasers for the first time.This paper provides some new research basis for understanding the establishment process of dispersion-tuned swept-fiber lasers and their potential application in the future.展开更多
基金National Key Research and Development Program of China(2023YFF0715700)Fundamental Research Funds for the Central Universities(2023CDJKYJH064)Chongqing Talents:Exceptional Young Talents Project(CQYC202005011)。
文摘This paper presents a wavelength-stepped swept laser based on a dispersion-tuned swept laser with the integration of a Mach-Zehnder interferometer,enabling a transition from continuous wavelength sweeping to wavelengthstepped sweeping.A comprehensive investigation of this laser is conducted,wherein different modulation schemes are employed to dynamically compare the switching mode,static-sweeping mode,and sweeping mode;the absence of mode hopping in the sweeping mode of the laser is verified.However,it is observed during experiments that the wavelength always remains stationary for a long time during the initiation of sweeping and change in sweeping direction,exhibiting latency compared to the modulation frequency variations.Through a simplistic modeling analysis of the composite cavity,it is revealed that the detuned state of the sub-cavity plays a critical role in the stable operation of the laser.Subsequently,simulation verification using the Ginzburg-Landau equation supports this observation.Additionally,compared to dispersion-tuned swept lasers,not only the linewidth significantly is narrowed in the proposed laser,but it also demonstrates enhanced stability during the sweeping process.This study provides,to our knowledge,a new laser source for ultra-fast optical imaging,ranging,and sensing applications,and presents novel methods and theoretical models for linewidth compression in swept lasers.
基金supported by the National Natural Science Foundation of China(Nos.61875026 and 61505017)the Foundation and Cutting-Edge Research Projects of the Chongqing Science and Technology Commission(No.cstc2018jcyjAX0122)the Graduate Student Innovation Program of the Chongqing University of Technology(No.ycx2018238)
文摘We demonstrate a fiber refractive index（RI） sensor based on an excessively tilted fiber grating（ExTFG）immobilized by large-size plasmonic gold nanoshells（GNSs）. The GNSs are covalently linked on ExTFG surface.Experimental results demonstrate that both the intensity of the transverse magnetic（TM） and transverse electric（TE） modes of ExTFG are significantly modulated by the localized surface plasmon resonance（LSPR） of GNSs due to the wide-range absorption band. The wavelength RI sensitivities of the TM and TE modes in the low RI range of 1.333–1.379 are improved by ～25% and ～14% after GNSs immobilization, respectively, and the intensity RI sensitivities are ～599%/RIU and ～486%/RIU, respectively.
基金National Natural Science Foundation of China(61927818,61975022)Chongqing Talents:Exceptional Young Talents Project(CQYC202005011)National Science Fund for Distinguished Young Scholars(61825501)。
文摘In this paper,we studied the dynamics of a dispersion-tuned swept-fiber laser both experimentally and theoretically.By adding a dispersion compensation fiber and an electro-optic modulator in the laser cavity,an actively mode-locked laser was obtained by using intensity modulation,and wavelength sweeping was realized by changing the modulation frequency.Using a high-speed real-time oscilloscope,the dynamic behaviors of the swept laser were investigated during wavelength switching,static-sweeping cycle,and continuous sweeping,respectively.It was found that the laser generates relaxation oscillation at the start of the sweeping mode.The relaxation oscillation process lasted for about 0.7 ms,and then the laser started to operate stably.Due to the nonlinear effect,new wavelengths were generated in the relaxation oscillation process,which is not beneficial for applications.Fortunately,relaxation oscillation disappears if the laser starts up and operates in the continuous sweeping mode,and the good sweeping symmetry between the positive sweep and negative sweep increases the application potential of the laser.In addition,the instantaneous linewidth is almost the same as that in the static state.These results describe the characteristics of the laser from a new perspective and reveal,to the best our knowledge,the intensity dynamics of such lasers for the first time.This paper provides some new research basis for understanding the establishment process of dispersion-tuned swept-fiber lasers and their potential application in the future.
